SYSTEM AND METHOD OF DISINFECTING AN OCCUPIED ENVIRONMENT USING GERMICIDAL

RADIATION

CROSS-REFERENCE TO RELATED APPLICATIONS

The current application claims priority to U.S. Provisional Patent Application No. 63025164, filed May 14, 2020; U.S. Provisional Patent Application No. 63057777, filed July 28, 2020; U.S. Provisional Patent Application No. 63060058, filed August 1, 2020; and U.S. Provisional Patent Application No. 63160787, filed March 13, 2021, the entire contents of which are incorporated by reference herein.

TECHNICAL FIELD

The presently disclosed subject matter is generally directed to a system and method of using germicidal radiation to disinfect an environment.

BACKGROUND

The spread of communicable diseases presents a challenge to protecting individuals in a society where people live in close proximity to each other and commonly share space in restaurants, retail environments, offices, hotels, and other public use facilities. For example, both viral and bacterial infections can be transmitted by physical contact with surfaces upon which the infectious agents reside. Further, there is an increasing awareness and concern worldwide of the possibility of widespread outbreaks or pandemics of communicable disease. These concerns stem in part from possible spontaneous mutations of influenza, CGViD-19, and other viruses, as well as the increasing resistance of bacterial strains to conventional and newly developed powerful antibiotics.

Ultraviolet germicidal irradiation is a disinfection method that uses UV radiation at a sufficiently short wavelength to break down harmful microorganisms. UV-C radiation with a wavelength of between 180-280 nm (and particularly between 240 nm-280 nm) has been found to be particularly effective. UV- B radiation with a wavelength of between 280-320 nm has also been shown to have germicidal properties. The relatively short wavelengths of UV-C and UV-B radiation are harmful at the micro-organic level by destroying the ability of microorganisms to reproduce. Specifically, a disruption in the DNA and/or RNA chemical structure prevents microorganisms from replicating, thereby rendering them inactive and unable to cause infection. However, disinfecting using UV radiation has been limited, due primarily to the requirement that existing systems be unoccupied by people. The precaution stems from the fact that UV exposure to unprotected skin can produce various negative effects including erythema, photosensitivity, skin aging, immune system damage, and even increased occurrences of skin cancer. In addition, effects of UV exposure are those that affect the eyes, producing photokeratitis, conjunctivitis, and other corneal injuries (e.g., cataracts). The wavelengths most effective for germicidal uses are also the wavelengths that are most destructive to human tissue. As a result existing systems cannot be used in areas populated by people that are not properly protected from UV radiation.

Therefore, it would be beneficial to provide a system and method of using germicidal radiation to disinfect an environment that includes people.

SUMMARY

In some embodiments, the presently disclosed subject matter is directed to a system for disinfecting an environment or a zone in an environment. Specifically, the system includes an environment defined by a floor and a reference point above the floor. The system further includes one or more unprotected persons positioned within the environment or zone. The system comprises a plurality of low-wattage germicidal radiation emitters positioned in an array above the reference plane. The array of germicidal radiation emitters disinfect the environment, including the one or more unprotected persons therein.

In some embodiments, the environment is selected from an indoor environment, an outdoor environment, or a vehicle.

In some embodiments, the environment is a room in a building, a healthcare facility, a nursing home facility, a store, a restaurant, an office building, an airport, a hallway, a lobby, or a school.

In some embodiments, the low-wattage germicidal radiation emitters emit germicidal radiation directly onto unprotected persons in the environment.

In some embodiments, the low-wattage germicidal radiation emitters are LEDs.

In some embodiments, the environment is divided into one or more zones, each zone comprising a unique array of germicidal radiation emitters with respect to the number of emitters, intensity of emission, duration of emission, or combinations thereof.

In some embodiments, the system further comprises an element configured to communicate to unprotected persons in the environment how much time they are allowed to safely remain in the environment. In some embodiments, the system further includes a shield, cover, lens, wave guide, or other device that blocks or changes the direction of at least a portion of the germicidal radiation.

In some embodiments, the germicidal radiation emitters vary with regard to intensity, duration of use, position, or combinations thereof.

In some embodiments, the vehicle is selected from a bus, airplane, subway car, train, or other public transportation vehicle.

In some embodiments, the presently disclosed subject matter is directed to a method of disinfecting an environment. Particularly, the method comprises determining the maximum daily dose or amount of germicidal radiation exposure for an unprotected person within a 24-hour period in the environment. The method further includes determining the maximum allowable occupancy time an unprotected person may safely remain within the environment or zone of an environment within a 24- hour period. The method further comprises regulating the output of a multiplicity of low-wattage germicidal radiation emitters in the environment or a zone in the environment so that the germicidal radiation disinfects the environment, including one or more unprotected persons in the environment; and wherein an unprotected person is not exposed to more than the maximum daily dose when exposed to germicidal radiation in the environment up to the maximum allowable occupancy time.

In some embodiments, the method comprises directly emitting the germicidal radiation onto unprotected persons in the environment.

In some embodiments, the environment is selected from an indoor environment, an outdoor environment, or a vehicle, particularly an airplane or subway car.

In some embodiments, the environment is a room in a building, a healthcare facility, a nursing home facility, a store, a restaurant, an office building, an airport, a hallway, a lobby, or a school.

In some embodiments, the environment is divided into one or more zones, each zone comprising a unique array of germicidal radiation emitters with respect to the number of emitters, intensity of emission, duration of emission, or combinations thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a perspective view of an environment comprising germicidal radiation emitters in accordance with some embodiments of the presently disclosed subject matter.

Fig. 2a is a top plan view of emitters held with support wires in accordance with some embodiments of the presently disclosed subject matter. Fig. 2b is a top plan view of emitters held in place with a net configuration in accordance with some embodiments of the presently disclosed subject matter.

Figs. 3a and 3b are top plan views of emitter arrays in accordance with some embodiments of the presently disclosed subject matter.

Fig. 4 is a perspective view of an environment comprising a plurality of emitters in accordance with some embodiments of the presently disclosed subject matter.

Fig. 5 is a front plan view of an emitter comprising a waveguide in accordance with some embodiments of the presently disclosed subject matter.

Fig. 6a is a front plan view of an environment comprising an emitter arrangement that includes a shield in accordance with some embodiments of the presently disclosed subject matter.

Fig. 6b is a front plan view of an environment comprising an emitter arrangement with an apertured shield in accordance with some embodiments of the presently disclosed subject matter.

Fig. 7 is a perspective view of a vehicle comprising a plurality of emitters in accordance with some embodiments of the presently disclosed subject matter.

Figs. 8a and 8b are perspective views of protective headwear in accordance with some embodiments of the presently disclosed subject matter.

Fig. 9a is a front plan view of a healthcare setting comprising a frame in accordance with some embodiments of the presently disclosed subject matter.

Fig. 9b is a side plan view of a healthcare setting comprising a patient shield in accordance with some embodiments of the presently disclosed subject matter.

Fig. 10 is a graph illustrating the range of possible log inactivation of SARS-COV2 in air.

DETAILED DESCRIPTION

The presently disclosed subject matter is introduced with sufficient details to provide an understanding of one or more particular embodiments of broader inventive subject matters. The descriptions expound upon and exemplify features of those embodiments without limiting the inventive subject matters to the explicitly described embodiments and features. Considerations in view of these descriptions will likely give rise to additional and similar embodiments and features without departing from the scope of the presently disclosed subject matter.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which the presently disclosed subject matter pertains. Although any methods, devices, and materials similar or equivalent to those described herein can be used in the practice or testing of the presently disclosed subject matter, representative methods, devices, and materials are now described.

The terms "a", "an", and "the" refer to "one or more" when used in the subject specification, including the claims. It will be further understood that the terms "comprises," "comprising," "includes," and/or "including" when used herein do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

Unless otherwise indicated, all numbers used in the specification and claims are to be understood as being modified in all instances by the term "about". The term "about" when referring to a value or to an amount of mass, weight, time, volume, concentration, and/or percentage can encompass variations of +/-20%, +/- 10%, +1-5%, +/-1 , +/- 0.5%, +/- 0.1%, from the specified amount.

As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

The presently disclosed subject matter is generally directed to a system and method of disinfecting an occupied outdoor or indoor environment comprising unprotected persons using direct irradiation. In other embodiments, irradiating environments occupied by persons protected with some level of UV protection on skin and eyes is also disclosed. The steps include determining or deciding the duration of time within a 24 hour day that a person will be allowed in the environment (“maximum allowable occupancy time”), deciding what level or dose of germicidal radiation will be allowed to fall on persons in the environment during that exposure time, usually determined by the “maximum allowable daily safe dose” or “Maximum Allowable Dose” established by local government or other agencies (e.g. ACGIH guidelines in the US, a.k.a. Threshold Limit Values orTLV’s), calculating the maximum amount of flux or irradiance of germicidal radiation determined to safe for exposure to unprotected persons by the equation below, and then configuring a germicidal radiation (since most germicidal radiation is in the UVC band of radiation, between 200 and 280 nm, the term “UVC” may also be used interchangeably with any form of germicidal radiation) emitter or emitters to emit no more than the “Maximum Allowable Irradiance” into the environment:

Maximum Allowable Irradiance = Maximum Allowable Dose / Maximum Allowable Occupancy Time

The term “irradiance” refers to the transmission rate of radiant energy per unit area of a given surface and is expressed in power of emitted radiation per area (e.g., Joules/second/m ² or Watts/m ² ). The “maximum allowable occupancy time” or “occupancy time” refers to the amount of time a person is allowed to be exposed to such levels of radiation, and is expressed in seconds, minutes, or hours. The “maximum allowable dose” is the maximum amount of radiant energy a user can come into contact with in a 24-hour period, expressed in energy per area (e.g., Joules/m ² ).

Germicidal radiation can include ultraviolet radiation and/or high intensity narrow spectrum (HINS) light. As set forth above, “UVC” refers ultraviolet radiation with a wavelength of between about 200-280 nm. “UVB” refers to ultraviolet radiation with a wavelength of between about 280-320 nm. The relatively short wavelengths of UVC and UVB radiation are harmful to forms of life at the micro-organic level by causing photochemical changes in nucleic acids such that their DNA and/or RNA chemical structure is disrupted. “HINS” refers to “high intensity narrow spectrum” light of about 400-420 nm which kills microorganisms.

The term “environment” can refer to any of a wide variety of indoor or outdoor spaces that are designed to be occupied by persons. Thus, in some embodiments, an environment includes the indoor space in a building, room, or a series of rooms inside and part of a building. In some embodiments, an environment can include one or more rooms having doors that can be closed to separate them from adjacent rooms. Particularly, the environment can include (but is not limited to) retail stores, grocery stores, offices, restaurants, hospitals, nursing homes, health care facilities, physical fitness centers, gymnasiums, schools, government buildings (e.g., courthouses), private homes, courtyards, walkways, vehicles (e.g., automobiles, trucks, buses, airplanes), hotels, theaters, entertainment venues, indoor and outdoor sporting arenas, patios, gardens, spas, recreational facilities, manufacturing facilities, military facilities, and the like. Elevators, hallways, closets, attics, walled porches, bathrooms, kitchens, basements, dens, rooms of any function, etc. (not an exhaustive list) within the building are included in this definition of an indoor environment.

The term “indoor environment” includes any indoor space designed for occupancy of persons comprising walls equipped with a ceiling, a floor, and doors for persons to enter and exit the environment. A room is defined as a part of the inside of a building that has been partitioned off from other parts of the inside of the building by walls, ceiling, floor, or other solid partitions and may or may not be isolatable from adjacent rooms by barriers such as doors that can be closed. A room can also be defined herein as any actual, arbitrary, or artificial boundary separating one space in an environment from another space in the environment.

However, the term “environment” is not limited and can also include outdoor spaces, such as unwalled porches, patios, outdoor dining areas and reception areas, outdoor stadiums and facilities hosting sporting events, sidewalk areas, swimming pool areas, and any other outdoor areas that can be equipped with the system disclosed herein.

As set forth above, the disclosed system and method comprises delivering an amount of germicidal radiation to an environment. One embodiment of environment 5 is illustrated in Fig. 1. As shown, the environment can include a large indoor building area with high ceiling 10 and flooring 11. The environment can optionally be subdivided by aisles 15, shelving 20, merchandise 25, and the like (e.g., using physical and/or non-physical barriers). These subdivisions of an environment, whether by physical boundaries or boundaries defined more or less by the areas of emittance of various emitters located in the environment, are called zones or partitions in or of an environment. As described in more detail herein below, environment 5 can be divided or subdivided into zones and/or partitioned areas wherein different levels of germicidal radiation intensity or irradiance can be used in the different zones. Specifically, different levels of radiation can be emitted depending on one or more factors, such as the presence or absence of persons in that zone of the environment, or the maximum allowable occupancy time of the different zones, or some other criteria. An example of a zone within and environment is depicted in Figure 4, where additional disinfecting UVC emissions are provided in the aisle by emitters 30b mounted on the top of the merchandise racks, to provide additional disinfecting of the aisleway when motion detectors focused on the filed of view of the aisle determine that there are no persons in the aisle. Thus, the aisle becomes a separate zone of emissions within the environment that may have levels of emissions that are different from those outside the aisle. Another way a zone in an environment is defined is a second area or environment within or nearby to a first area or environment wherein the germicidal radiation emitted differs in at least one of intensity, direction, duration, shape, factors by which the emissions are controlled (e.g. sensors or control algorithms), maximum allowable occupancy times, type of emitter, number of emitters, shielding, attenuation of radiation intensity by means of lenses, covers, films, etc., and any other conceivable means by which the emission profile over time in one area or zone or partition is differentiated from the emission profile in another area or zone or partition. Usually, the different zones will be defined mostly vertically and will be able to be mapped on a floor plan; but alternatively, different zones can also be stratified through an environment diagonally or horizontally, that is, one zone may cover a lower volume of an environment, and another zone an upper volume.

Environment 5 can include at least one emission reference point where the emitted radiation will be measured to determine whether or not persons could be exposed to radiation levels in excess of the maximum allowable dose. The irradiance is measured at a certain point in the environment chosen to maximize the safety of persons, a “reference point”, such as eyelevel for an average height person standing in a particular spot in the environment. Since persons will normally be moving about the environment, in most cases it will be advantageous to measure the irradiance along a “reference plane” in the environment, which is defined as a plane parallel to and above the floor of an environment or a zone of an environment, the height of which is chosen for any reason, but usually is chosen as a point where measuring the emitted radiation will ensure the safety of persons in the environment. Since the preferred and most efficient manner of disinfecting an occupied environment and persons in the environment will usually entail emitting radiation from above the heads of the persons, the heads of the persons may be the point of the body closest to the emitters and therefore subject to the most intense radiation. Taller persons will in those situations be closer to the emitters and therefore more in danger to being overexposed to radiation than shorter persons. Therefore, in such situations it will be important to choose a height, for example 6.5 feet above the floor or two meters above the floor, at which the emissions will be measured and controlled such that a person 6.5 feet tall can freely move about anywhere in the environment and not be exposed to too much radiation. The emission reference point or reference plane can vary from environment to environment or zone to zone within an environment and is not fixed or need not be the same for all environments or all zones in an environment. Choosing a reference plane two meters above the floor, for example, and ensuring that the average emissions as measured at various points along this plane does not exceed the maximum allowable irradiance, would protect the majority of persons six feet and shorter from being exposed to excess radiation if they were to remain in that environment for the entire occupancy time set for that environment, assuming the radiation they are being exposed to is primarily from above that reference point. Another example of an emission reference point can be a stationary place in the room, chosen where a person may sit or stand for longer periods of time. For example, in a restaurant, the emission reference plane in a zone that includes dining tables could be the average height above the floor of the top of the head of a 6-foot-tall person seated at a dining table. Another example would be in a classroom, there the emission reference point or plane could be the height above the floor of the average student’s head or eyes or the tallest student’s head or eyes when they are sitting upright at their desks.

The disclosed system and method can provide uniform or relatively uniform emissions of disinfecting germicidal radiation through a plurality or an array of emitters, especially when compared to the high degrees of nonuniformity of emissions delivered by status quo Upper Room UV systems.

The term “uniform” may be defined as the highest level of irradiance measured anywhere across the emission reference plane being not more than about 100, 90, 80, 70, 60, 50, 40, 30, 25, 20, 15, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1.75, 1.5, 1.25, or 1.1 times greater than the lowest level of irradiance measured anywhere across this plane. Alternately, “uniform” may be defined as follows: when measuring the emittance in the environment along the reference plane, when moving from beneath one emitter in the array of emitters to beneath a second emitter in the array of emitters, the highest level of irradiance measured will not more than about 100, 90, 80, 70, 60, 50, 40, 30, 25, 20, 15, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1.75, 1.5, 1.25, or 1.1 times greater than the lowest level of irradiance measured in the reference plane.

The disclosed method can include disinfecting objects in an environment, such as people, furniture, clothing, floors, and the like. The term “disinfect” refers to the destroying, neutralizing, and/or inhibiting the growth of one or more biological contaminants. Suitable biological contaminants can include (but are not limited to) bacteria, viruses (influenza, COVID-19, etc.), molds, and the like. In some embodiments, the biological contaminants can be disinfected to a level at least equal to 1 log inactivation or kill (90% destruction of organisms or number of colonies of organisms) during the occupancy time or during a 24 hour period of emitting germicidal radiation. In other embodiments, a level of disinfecting pathogens, particularly airborne pathogens, to a level at least equal to 2, 3, 4, 5, 7, 10, 15, 20, 25, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, or higher inactivation or kill may be achieved with this system and method, all while avoiding exposing persons in the environment to germicidal radiation in excess of allowable safe levels.

For the benefits of the present invention to be appreciated, it will be necessary to review the current state of the art of disinfecting occupied environments using germicidal radiation and the problems thereof. Upper Room UV Systems are discussed at length in Chapter 9 of the Ultraviolet Germicidal Irradiation Handbook, W. Kowalski, Springer, 2009, pp. 211-232. These systems are designed for tuberculosis wards, medical facilities, schools, and other buildings where highly contagious infectious diseases are known to be transmitted. These systems emit intense UVC radiation in the ceiling area of a room to destroy any organisms that float in the air up into the ceiling area. These systems take great care to not allow radiation to directly fall from the emitters onto persons in the room: the radiation is emitted horizontally and vertically using louvers, wave guides, reflectors, etc. to ensure the radiation first hits the walls or ceiling before being reflected, at much reduced levels, onto persons below. Thus, only secondary radiation is allowed to contact persons in the environment. The emitting units are typically one large unit hung from the ceiling in the middle of a room or three or four units attached to the walls near the ceiling emitting horizontally across the upper part of the room. Because the distance that the radiation needs to travel to be effective in disinfecting the air tens of feet from the emitter (about half the length of the room or more), the emitters typically use low or medium pressure mercury-containing UVC bulbs with typical input wattages “from about 18 to 36 W,” a relatively high amount of power. Because theses emitters are large and require relatively high power, it is advantageous to minimize the number of emitters and increase the power output of the emitters to reduce equipment and installation costs. Because these emitters are fewer in number and are designed to put out more intense radiation, Kowalski reports, “Most Upper Room irradiance fields will fall within about 0.001 -10W/m2, or a four log range, although irradiance may be much higher close to the fixture.” (p. 227) The Upper Room UV systems are large, bulky, heavy, difficult to install, expensive to install, create highly non-uniform radiation output profiles, use UVC-emitting elements (lamps, bulbs) that consume significant amounts of power, can easily break, have to be replaced relatively frequently (every year or two), and contain mercury (therefore creating safety and environmental hazards with handling and disposal), use UVC-emitting elements that emit UVC radiation far in excess of what persons could be safely exposed to (therefore requiring complex measures to mitigate these safety issues, which increases cost and decreases efficiency), are not primarily designed for disinfecting persons and the air/objects immediately surrounding persons in an environment, do not lend themselves to temporary or outdoor installations, are limited to high-ceiling rooms and high overhead clearances to operate effectively (and therefore are not suitable for passenger aircraft, subway cars, or most other vehicles), . The net effect of these deficiencies result in systems that are not suitable for wide-scale deployment in environments other than the narrow, limited niches into which they have currently been sold.

It is an object of the present invention to help address all of these deficiencies and provide the most efficient, safe, cost-effective, and environmentally responsible means possible for controlling pathogens in a wide range of environments, not just in tuberculosis wards or facilities where high transmission of infectious diseases has already been confirmed. It is difficult to imagine Upper Room UV systems being adapted to environments with low ceilings, such as in a passenger aircraft or in a subway car, or in a home or any indoor environment with a low ceiling, as is the present invention able to be used. It is unheard of to use an Upper Room UV system outdoors, and if it were so employed the persons and the air around the persons would not be disinfected due to the absence of a ceiling or walls to allow reflected radiation to fall on persons below, whereas the present invention, which allows for direct irradiation of persons in an area, readily lends itself to adaption in outdoor settings. The extreme variability in measured irradiance fields, reportedly a four log range or more, makes the task of ensuring that persons in the environment, no matter where they may move about the environment or remain still in one area of the environment, do not receive doses of radiation that exceed the maximum allowable dose that much more difficult; safe operation is more difficult to achieve with Upper Room UV systems than the present invention.

The easiest way to envision how the present invention is clearly different from the Upper Room UV systems and solves the disadvantages of those systems is to imagine that the best way to provide safe, highly uniform emissions onto persons in an environment is to provide one continuous two dimensional emitter on the ceiling or suspended above the entire environment or zone of an environment. If a flat panel screen could be devised which emits UVC radiation and could be made large enough to stretch across the entire ceiling of the environment or zone in an environment, this would provide the most uniform emissions possible. The most uniform and efficient emissions will be achieved with a high number of tiny, low output emitters arranged evenly across the entire environment ceiling emitting downwards onto persons. Since no such technology is known to exist, the present invention attempts to approximate this ultimate flat-panel emitter by providing a multiplicity of efficient, low-wattage emitters arranged in a manner to provide uniform coverage of the environment, herein termed an “array” of emitters that are mounted preferably above persons in the environment and preferably oriented downwards so as to emit germicidal radiation directly onto the environment and persons in the environment. Unlike the Upper Room UV systems that employ one large central emitter in the middle of the room or several large emitters on the walls employing multiple single lamps in one housing, where each lamp or emitting element requires tens of watts of power to operate and is quite inefficient in converting electrical energy to UVC energy, it is the purpose of the present invention to employ a plurality of much lower wattage emitters - each element of which consumes less than ten watts of power, and preferably less than one watt of power, and more preferably less than a tenth of a watt of power - and distribute those emitters more or less uniformly across the environment in an array, preferably across the area above persons in the environment, and most preferably directed downward with emissions directly onto persons and objects in the environment to minimize the inefficiencies created by needing to reflect the radiation off of other surfaces, where a large amount of the energy is lost and turned into heat in the environment.

Low wattage emitters are herein defined as a single UVC emitting element that consumes less than 10 watts of power per emitting element, preferably less than 1 watt of power per emitting element, The ideal low-wattage emitter useful in the present invention is the LED. LED’s emitting UVC radiation are known and are commercially available. Power requirements for one LED element or a single LED emitting device are often measured in milliwatts. For example, International Light Technologies’ E275-3 275nm UVC LED has a maximum output of 6mW of UVC with an input of 50mA of 6V current, or 300mW of input power. Multiple LED emitters are frequently mounted on a single housing to increase the output from a device mounted in one location. Employment of such devices is within the scope of this invention, but employing single LED emitters at each emitting point of an array is believed to be preferable for attaining more uniform output into the environment if this can be achieved cost effectively (the practicality of mounting many single LED emitters each in a different location in the array must be weighed with the cost of doing so. It may be found that at each emission point in an array, a multiplicity of LED emitting elements mounted in a cluster are more economically efficient. A multiplicity of LED emitters mounted on a single housing does not constitute a higher wattage emitter for the purposes of this invention. The definition of low wattage emitter herein is entirely related to the simplest emitting element of the system or emitter housing, such as a single mercury vapor bulb or a single LED chip.

Very low output low pressure mercury vapor lamps may also become available for this application, and the lowest input wattage found uses on the order of 5 watts of power. These types of low-wattage bulbs using existing low pressure mercury vapor technology with input wattages less than 10 watts are also envisioned in this invention, but the germicidal radiation output of each of these may still be too high to be useful in low-ceiling applications of the present invention and may have to be greatly curtailed to avoid hot spots and overexposing persons in the environment. The inefficiencies of even these low output bulbs plus the fact that they still contain hazardous materials do not lend themselves to being the preferred option for use in the present invention.

Suitable emitters can be chosen from any emission technology that emits germicidal radiation. For example, one or more of low and medium pressure mercury vapor lamps, LEDs, excimer lamps, lasers, and the like can be suitable. For germicidal radiation emitters with emissions exclusively in non- visible wavelengths, the emitter circuitry can include a light, diode, and/or visual indicator, possibly shining in the same area as the UVC emitter, so that a person in the environment can immediately determine whether or not an emitter is emitting germicidal radiation.

The disclosed system and method include direct germicidal radiation irradiation of persons and objects in an environment. The term “direct” indicates that that radiation proceeds directly from the emitter in a continuous path through the air in the environment and onto a person in the environment without first hitting some other object like a wall or ceiling and then being reflected onto the person in the environment. In other words, “direct” or “directly” refers to radiation that is not reflected off any object before it comes into contact with a person in the environment. In comparison, reflected radiation can be considered secondary radiation. It should be appreciated that secondary radiation will also contact persons in the environment.

In this invention, safe and controlled amounts of radiation may be directly emitted onto persons exposing persons directly to radiation from an emitter. Direct irradiation of persons and objects in the environment is a much more efficient way to disinfect an environment, since typically less than 20% of the radiation hitting a surface is reflected or reemitted. It is noted that included within the definition of “direct,” the radiation may first be passed through an attenuation device to shape and control the output of the emitter, such as a waveguide or lens or a film or shield that blocks only a portion of the radiation but allows some to pass through; these devices may still be used in between the emitter and persons in the environment and still fit within the definition of “direct.” What is not considered direct irradiation is when the radiation first is directed upwards or sideways onto walls or other objects to soften or reduce the intensity of the radiation. These types of systems are envisioned in some aspects of this invention, where the radiation can first be reflected off walls, the ceiling, and/or other objects in the environment before reaching persons standing on the floor in the environment, but these embodiments do not fall under the definition of “direct” irradiation of persons. Thus, a direct irradiation system and method allow for more efficient and cost-effective means of delivering the same amount of energy onto persons in an environment than the current state of the art will allow. The term “direct germicidal radiation coverage” indicates that at least 5-100% of the floor area of an environment (e.g., at least about 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100%) or zone in an environment is directly illuminated with germicidal radiation (or would be if no persons or objects were present in the environment).

It should also be noted that indirect emissions into the environment are also contemplated with this invention, as are combinations of direct and indirect emissions. Indirect emissions in this invention are defined as germicidal radiation emissions that are directed in full or in part first onto a surface, such as a painted wall or ceiling, and then the reflected and absorbed/reemitted UVC energy then finds its way to a person or other objects in the environment. The benefits of indirect emissions are that arrangements of emitters, such as an array of emitters as described herein, along with certain surface coatings may result in more uniform emissions as measured on the reference plane. Even though indirect emissions will be less efficient due to the fact that typically more than 50% and even more than 80% of the UVC radiation is not reflected and turned into much less useful heat energy, there may be other advantages to doing so, such as increased uniformity or greater customer acceptance. In any event, employing indirect emissions along with the arrays and lower wattage emitters and other aspects of this invention will result in a product that is much better than current Upper Room UV systems.

“Unprotected persons” are defined herein as persons that are not wearing germicidal radiationblocking protective eyewear and/or that have at least some portions of skin that are not covered by clothing, PPE (personal protective equipment), or a protective skin coating. PPE can include any article to be worn by an individual for the purpose of preventing or decreasing personal injury or health hazard due to exposure to germicidal radiation. Protective skin coatings can include suntan lotion, a liquid skin coating, or any substance applied to the skin to block germicidal radiation. A “protected person” is defined herein as a person that is wearing eyewear and protective clothing or skin coatings that block at least a portion of the radiation from reaching the person’s eyes and skin.

A “plurality of low-wattage germicidal radiation emitters positioned in an array above the reference plane” is defined as more than one low-wattage germicidal radiation emitters mounted above the reference plane and oriented in a way as to provide the greatest uniformity of coverage of the environment with germicidal radiation. For example, in a hallway eight feet wide and forty feet long, this arrangement or array of emitters to provide the most uniform and cost-effective coverage may entail single UVC LED’s (each mounted on a support base for ease of mounting and wiring connections) mounted six feet apart in the middle of the ceiling of the hallway pointed downward. At each location on each base or emitting element support, multiple emitters may be mounted, such as three or four LED’s mounted on a single support base in a cluster of LED’s. This cluster, since the LED’s are so close, would still be considered to be one point or node in the array. An array consists of at least two such points spaced at least several inches apart, or more preferably at least six inches apart, or more preferably at least 12 inches apart, or more preferably at least 24 inches apart. Even though from a uniformity standpoint, closer is better, yet it is believed that for many applications, close spaced array nodes will result in both too much power output (exceeding safe limits) and will be too expensive. It is believed based on calculations that the preferred distance between array nodes will be multiple feet: 2, 3, 4, 5, 6, 6, 8, 9, 10 or more feet apart. The optimum node distance will be determined by the application, how far the emitters are from occupants, the output of the emitters, and a variety of other factors. The space between two adjacent nodes in the array need not be the same throughout the array; uniformity may dictate even spacing, but practical installation limitations may not always allow optimal or even array spacing.

The array may be linear, as described in the hallway example above, and just two emitters located at least one foot apart can be considered an array for the purposes of this invention. Arrays may be two or even three dimensional. Some arrays are evenly spaced two-dimensional emitter nodes on a rectangular or triangular grid. For example, a checker-board type arrangement with emitters located on the corners of the checkerboard every four feet apart in both the x and y directions is an example of a two-dimensional square array in this invention. Arrays composed of nodes arranged in diamonds, circles, hexagons, etc. may be used. Any arrangement or combination of arrangements or even random arrangements of emitter nodes are allowable in the array. Some emitters may all be mounted above the reference plane, but some emitters may be mounted higher above the reference plane than others, thus, the emitters may be mounted in a three-dimensional array arrangement rather than just a two- dimensional array arrangement. Furthermore, not all emitters in an array need be emitting at the same output level; each emitter may be adjusted or attenuated independently of the other emitters in an array to achieve the desired overall output profile.

The emitters in some embodiments may be positioned or mounted below the reference plane or on the same level as the reference plane. In some embodiments there are combinations of at least one emitter mounted above the reference plane and at least one emitter mounted at or below the reference plane.

As shown in Fig. 1 , emitters 30 are positioned throughout environment 5, such as above the head level of persons in the environment and directed to emit germicidal radiation downward, including directly onto persons in the environment. In some embodiments, a plurality of emitters is included in environment 5 (e.g., about 2-100 or more). The emitters can be arranged to emit disinfecting radiation into the environment and onto persons in the environment in the areas in which disinfecting is desired.

Any desired element can be used to mount emitters 30 in a particular environment. For example, wires, ropes, mechanical elements (e.g., screws, bolts, fasteners), magnets, adhesive, or other support elements can be used to position emitters 30 at a desired location in an environment. The mounting can also be accomplished by attaching the emitters and emitter controls to drywall, framing, lighting boxes, and/or any number of conventional methods of mounting lighting or other objects in a room.

Optionally, the mounting can be accomplished by installing a self-supporting or non-selfsupporting frame in the environment, including frames made of metal, plastic, or wood, onto which the emitters and emitter controls are mounted. A self-supporting frame can transmit the weight of the frame and emitters directly onto the floor, rather than mounting the emitters on the walls or ceiling. The frame can be installed close to the walls and ceilings to take up less space in the environment, or the frame could be located in other parts of the room or extend outward away from the walls, ceiling, and floor as desired. Mounting the emitters on frames may be desirable if the exact locations are unsure at the time of installation, and some adjustment of emitter position is desirable after the emitters are turned on and radiation levels measured in the environment. Frame-mounted emitters are also desirable for temporary installations, installations where mounting the emitter on the wall or ceiling is not feasible, or when damaging the wall or ceiling is not desired.

Another variation of the frame mounted emitters is a non-self-supported frame that is mounted onto the wall or ceiling and onto which the emitters can be mounted. Track lighting is one type of embodiment of this wall or ceiling mounted frame-mounted type of emitter installation, where the emitters can be located on the track and moved into various positions in a similar way as track lighting fixtures can be moved.

In some embodiments, emitters 30 can be mounted on a movable arm or swivel that allows the emitter to be moved in or out or around a fixed position. Another type of emitter mounting support that is envisioned is a rope or net type of emitter mounting, where a rope or net or wire is attached to the ceiling, wall, or frame from one point to another, and the emitter(s), along with power and control wiring, is mounted along this rope or net or wire support. This net or wire approach may be useful in minimizing the amount of frame material needed and allowing for significant flexibility in location of the emitters. The framing materials ideally are chosen with aesthetic appeal in mind and may even serve a decorative purpose.

For example, Fig. 2a illustrates one embodiment of emitters 30 mounted on wire or strip 40 that can be strung across or attached to a ceiling or wall, etc. in an environment. Alternatively, Fig. 2b illustrates net support 45 comprising emitters 30 arranged in an array (e.g., in a square pattern every four feet apart with emitters spaced as desired). The net and/or emitters can be supported by securing the four corners or sides to supports or walls, on poles or any other element. Net 45 can be useful in outdoor environments, where there is no ceiling on which to mount emitters. Thus, the emitters can be mounted in a variety of locations in an environment. For example, emitters 30 can be mounted on ceilings, upper parts of the walls, at or above eye level, and the like. (“Eye level” refers to the height above the floor of the eyes of a person standing upright on the floor.)

Emitters 30 can be mounted at any convenient height in environment 5. The general rule is that the higher the mounting of emitters 30, the more powerful the emitters are and/or more emitters are needed to achieve the desired irradiation at eye level. Thus, mounting the array of emitters overhead in a large environment with high ceilings allows for fewer emitters spaced further apart than would be possible if the ceiling were lower. Higher power emitters may be required as the height above the floor is increased. Flowever, mounting the emitters higher and using higher power emitters allows for additional disinfection of air circulating above the persons in the environment. Thus, when deployed in large buildings with high ceilings, the emitters can disinfect areas using direct radiation near the floor where persons are located while simultaneously disinfecting the air above persons.

Emitters 30 can include any desired arrangement. For example, a single emitter can be positioned on the ceiling or wall of a smaller room. Single emitters may be suitable for smaller rooms. A single emitter would not be considered an array, however. Alternatively, an array of emitters can be located in various points throughout an environment. The term “array” refers to an arrangement of a plurality of emitters around an environment, room, or zone, the purpose of which is to provide a more uniform emission of radiation. The array can emit radiation mostly downward or mostly upward, or an arrangement of emitters mounted on the upper portion of walls or at or above eye level could be emitting outward and downward and upward. An arrangement of emitters in an array is depicted in Figures 2b, 3a, and 3b.

The emitters can be arranged in any desired configuration within environment 5. For example, the emitters can be configured in rows or in a systemic pattern, as illustrated in Figs. 3a and 3b. Flowever, the presently disclosed subject matter is not limited and the emitters can be clustered or randomly positioned within the environment. In this way, uniform irradiance of emissions at a desired level in the environment is facilitated (e.g., eye level or some other selected height above the environment floor). If emitters 30 are spaced too far apart, a radiometer can measure higher levels of germicidal radiation directly underneath the emitters and significantly lower levels in between the emitters, and the emissions are non-uniform. In such embodiments, each emitter is creating a unique zone of emissions. Alternatively, the level of emissions within environment can be uniform through the entire building or in the areas where the most disinfection is desired by employing an array of emitters in the environment as described herein.

Alternatively, different zones in environment 5 can have different emitter arrays mounted at different heights. For example, a first array of emitters mounted on net 45 can be stretched about 12 feet above the floor in the general walkway areas and checkout areas of an environment. In the aisles between the shelving, a second array of emitters can be mounted above the shelving, which can be higher or lower than the height chosen in the checkout area.

In some embodiments, the arrangement of the locations of the emitters and an individual emitter output is designed and adjusted to give a fairly uniform of emission level throughout an emission zone. The term “fairly uniform” is used because it should be recognized that it will be impossible to have a multiplicity of emitters, or even the output from a single emitter, located in a room such that anywhere in the room or within the emission zone a person travels they will receive an exact same amount of radiation. For example, a person holding a radiometer six feet off the ground and moving around the room will be measuring different levels of radiation as they move closer to or further away from an emitter.

Multiple emission reference points and/or different emission zones in the same environment are also envisioned. For example, in one area or zone of the environment or room higher emissions are being emitted with a corresponding lower allowable occupancy time for unprotected persons, while in another part of the room lower emissions are being emitted with a corresponding higher allowable occupancy time for unprotected persons. Different zones may also be used in situations where persons are protected. For example, in a hospital, there may be one emission reference point for some emitters emitting in a first emission zone (e.g., on or near a patient in a bed), resulting in an emissions zone that includes the head of the bed and the patient’s upper body, and another emission reference point for other emitters emitting at different levels of radiation in other parts of the room, resulting in a second emissions zone (e.g., onto or near a caregiver standing in another part of the room). Because radiation can be directed and guided and shielded, different zones in the same environment can be thus created. In such cases, elements could be provided such as markings on the floor or different colors of visible light mixed with the germicidal radiation to signal to persons that they are moving from one zone to another zone.

The array configuration can provide locations for the emitters and optionally adjust the emissions to avoid significant hot spots or gaps of radiation, where significantly higher or lower levels of radiation would fall on a person if they were to stand in that spot for the duration of the allowable occupancy time. A uniform emission output or flux or irradiance within the zone at a particular height above the floor (e.g., the emission reference point or plane) is believed to be advantageous compared to a zone with an irregular and variable output. Particularly, uniformity is desired to avoid overexposing persons in some areas of the emissions zone and failing to adequately disinfect the air and surfaces in other areas of the emissions zone.

The distribution of emissions among a plurality of emitters 30 achieve a more uniform emission profile in the environment. In contrast, one large emitter hanging from the ceiling or installed on the wall could have too much emission closer to the emitter and too little further away, even if the average emission as measured around the room on the emission reference plane was found to be within the allowable emission level. Since persons in a room do not always continuously and randomly move around (i.e., they may stay in one spot for long periods of time), too-high and too-low emissions in some areas of the environment could be problematic in an occupied environment with a single emitter. However, an array of emitters arranged evenly across the ceiling or upper walls provides a more uniform level of radiation or emissions onto persons in the environment at various points on an emissions reference plane.

For example, LED germicidal radiation emitters (each single LED emitting element has less than 10 milliamps of radial flux output, for example part numbers E275-3, E275-3S, available from International Light Technologies (ILT)), arranged about uniformly around a room on the ceiling can produce a uniform output or level of radiation at the emission reference points or planes. Mounting the LEDs on strips (strip- mounted LEDs are also sold by ILT) with the desired distance between the emitters and mounting the strips across the ceiling as a quick and convenient way of mounting an array of emitters, is also contemplated.

Once in place, the output of the emitters can be adjusted to prevent the radiation from being too intense in one location in the room and not intense enough in other parts of the room, as measured at the emission reference points. The adjustments to the radiation measured at the emission reference points can be made by a number of methods, including relocating an emitter location, changing the number of emitters, using different types of emitters, adjusting the angle of the radiation emitted from an emitter, and for ceiling-mounted units, the emitters can be lowered from the ceiling to increase intensity. Alternatively, ceiling-mounted emitters can be raised to decrease the intensity for systems with downward directed emissions.

Some emitters will be equipped with variable emission controls that can electronically vary the level of radiation emitted from the emitter, such as a varying the voltage and/or current to the radiation- emitting element. In other embodiments, one or more emitters can be deactivated (e.g., permanently or temporarily turned off) for a period of time inside the allowable occupancy time to decrease the emission level. Further, a shielding positioned over or around an emitter can be used to limit or redirect the radiation from the emitter. In some embodiments, positioning a radiation barrier in between the emitter and the emission reference point (e.g., a wall around the circumference of an emitter) and extending the wall or barrier outward away from the emitter to have the effect of channeling the radiation in the direction that the wall or barrier is constructed, like a light-wave guide or a type of spotlight, may also be used.

Yet still another way of adjusting the output of an emitter is to put a semi-transparent material in front of part or all of the emissions from an emitter, such semi-transparent material being defined as a material that is transparent to some of the germicidal radiation yet does not allow some of the radiation to pass through. An example of this type of adjustment includes covering the emitter with a partially opaque film or glass that transmits some of the germicidal wavelengths or some of the germicidal radiation at a particular wavelength but not all, but due to the addition of substances to the film or glass, such as radiation blocking dyes or particles so that not all of the radiation at a given wavelength is able to pass through the film or glass. Optical lenses may also be used to focus or diffuse the output of an emitter or a cluster of emitters. For example, lenses are known to shape the output of LED’s so that a more uniform distribution of radiation on a two-dimensional surface (such as the reference plane) is known. Such lenses may also be employed in this invention at a node of an array; the use of lenses may perhaps even allow a single emitter or cluster of emitters to be used to achieve uniform emissions in a small room or zone of an environment.

Systems and methods that automatically adjust the output from the emitters in response to an input (e.g., a manual input or an automatically sensed input such as a radiometer mounted in the environment or an electronic motion detector detecting a person walking into or out of the environment) are also envisioned. Automatically sensed inputs can be provided from any number of sensors or inputs, such as the numbers of persons in an environment, the time a person has been in radiation emitting environments, the level or type of activity of persons in the environment, and the like. The action that the electronic circuitry takes on the emitter(s) in the environment includes to increase, decrease, or vary the emitted germicidal radiation according to a predetermined algorithm or plan.

In some embodiments, the presently disclosed subject matter can include tracking persons in an environment or zone in an environment or a plurality of environments or zones in an environment. In response to the tracking data, the emitted levels of radiation in an environment can be adjusted. Particularly, the data can include where a person is in the environment, how long a person has been in an environment, and/or where/how long a person has been in different environments (e.g., with different levels of emitted radiation). The person can be alerted or notified as to the amount of radiation they have been exposed to in a 24-hour period. For example, the presently disclosed subject matter includes an app on a person’s phone or Apple Watch® that keeps track of where a person has been and for how long in various environments with emitted radiation. The app can also estimate the percentage of total daily allowable dose the person has been exposed to. Further, a germicidal radiation sensor and associated circuitry can be used to alert a person to how much radiation they have been exposed to in a given period of time, possibly communicating to a phone, smart watch, or other portable device.

The disclosed system includes determining the amount of time that a person may be in environment 5 within a 24-hour period. The intention of this invention is to provide a system and method for disinfecting occupied environments. Higher intensity radiation can be used, and therefore higher degrees of disinfection can be achieved, if the allowable exposure time is shortened. It is therefore generally desirable to set the shortest maximum allowable occupancy time that is practical and allows for ample assurance of safety with some margin for error.

The allowable safe dose of germicidal radiation for unprotected eyes and skin in a 24-hour period may be set by federal regulations and guidelines. For example, the ACGIH (American Conference of Government Industrial Hygienists) and ICNIRP (International Commission on Non-Ionizing Radiation Protection) can be used. Alternatively, a different level as established by a qualified professional, such as a doctor in a hospital, may be established for an environment, in which case higher levels in excess of the ACGIH levels, for example for certain wards containing highly contagious pathogens, may be established. In other instances, current maximum exposure levels that apply to certain germicidal radiation wavelengths may be discontinued altogether. At this time the current maximum exposure levels for so called “deep UV” (UVC radiation in the about 207 to 222 nm wavelength range) are believed by some to be too stringent; they argue UVC radiation at these wavelengths is actually safe for human unprotected eyes and skin. If such determinations are made that for some wavelengths there are no limits to the allowable dose of radiation a person is allowed to be exposed to, then the “maximum allowable dose” that can be emitted on unprotected human eyes and skin can be adjusted accordingly within the scope of this invention.

Once the maximum occupancy time for the environment or zone within the environment is set, and the allowable safe dose of radiation for the wavelengths being emitted is established, the germicidal radiation emission rate or irradiance of the germicidal radiation for that environment or zone can be calculated using the equation already provided. Emitters 30 can be designed, installed, and adjusted to produce the desired irradiance to ensure that the maximum levels are not exceeded.

As one example, the maximum allowable time for a person to be present in environment 5 can be set to 8 hours (a typical employee workday). It should be appreciated that any desired amount of time can be chosen, from 24 hours to 30 minutes or less. The maximum daily dose of 254 nm radiation for unprotected eyes and skin is set at 60 J/m ² (ACGIH guidelines). 254 nm is the predominant wavelength of output of a typical and widely available low pressure mercury vapor lamp UVC emitter. Using emitters of this type, the maximum irradiance emitted into environment 5, measured at a predefined height or reference plane (e.g., about 6-7 feet from the ground to correspond to the maximum height of the majority of persons) is determined by the following formula:

60 J/m ² /(8 hr*60 min/hr*60 sec/min) = 0.002 W/m ² .

Thus, emitters in the array formation mounted on or below the ceiling and above persons in the environment would be limited to emit (on average) no more than 0.002 W/m ² when measured at a level 6-7 feet above the floor. In this manner, the environment can be disinfected with a safe dose of radiation, provided that administrative controls are in place to ensure that workers and customers do not spend more than 8 hours in environment 5 in a 24-hour period.

In embodiments wherein workers are present for 12-hour shifts, the emitters can be limited to 60 J/m ² /(12 hr*60 min/hr*60 sec/min) = 0.0014 W/m ² at the designated height from the floor. Since pathogens are disinfected to a greater extent when the irradiance is higher, disinfection is better and performed to a higher degree if the time that persons are allowed to remain in the environment is shortened. For example, if a retail store or a passenger airliner limited workers, customers, and other personnel to 4 hour shifts in a given 24-hour period, significantly more disinfecting can be accomplished in the environment, and the irradiance can be set to a higher level (e.g., 60J/m ² /(4hr*60min/hr*60sec/min) = 0.004 W/m ² .

Upper room disinfection devices are currently available for disinfecting the air above persons, but these units are higher-power disinfecting devices that emit radiation horizontally or upwards, away from persons. The disadvantage of these upper room systems is that to disinfect the air to a high degree, they emit intense radiation horizontally or upwards and intentionally avoid exposing persons below to direct germicidal radiation. Because of the high intensity of these emissions, the emitted radiation at the eye level of persons in the environment is usually highly non-uniform, with significantly higher levels of radiation measured as one approaches the unit. The non-uniformity of emissions from the upper room systems and the fact that persons and objects around persons in the environment are not being directly irradiated are the main problems with the prior art. Thus, in one embodiment, the disclosed system uses lower levels of radiation irradiated directly onto persons in the environment from an array of emitters, all of which together accomplish the desired goal of a uniform level of radiation for the disinfection and protection of persons in the environment.

The presently disclosed subject matter includes a method for disinfecting an environment and keeping persons in the environment safe by limiting the time persons spend in the environment. For example, employees can be trained to keep track of their time in the environment. Automatic whistles or other sounds or announcements can be transmitted to announce when one or more persons needs to exit the area. A mobile phone application can be used to keep track of the time in the environment. Further, the system can include tracking features that record when persons enter and exit an environment. The tracking can be manual or automatic, optionally with notifications provided when an employee’s allowable time is expired or about to expire. In other options, a monitor can be removably attached to or carried by an employee that records the amount of time an individual time spends in the disinfecting environment. When the person is about to meet or exceed an exposure limit, the person is notified via a warning or alarm, optionally with a display or voice activated response (e.g., similar to an Amazon Alexa® app that can answer questions and respond to voice queries). Signage can be posted at all the entrances stating that customers and all other persons are limited to a maximum time in this environment and that by entering the environment or building they agree to monitor their time in the environment and limit it to less than the maximum allowable time.

Thus, the presently disclosed subject matter is directed to a method of disinfecting an environment (which includes persons within the environment) using germicidal radiation. The persons are kept safe by selecting an allowable time that the person may remain in the environment, installing emitters to emit the radiation in the environment, limiting the emissions from the emitters to prevent persons from receiving greater than a daily safe dose of germicidal radiation during the allowable time, and optionally providing an administrative element to limit the time individuals spend in the environment.

In some embodiments, the emitters in the array can emit at multiple levels of emissions with the simple adjustment of current, voltage, and/or other electrical parameter (such as International Light Technologies’ E275-3 275nm UVC LED’s that can output 3 mW of optical output power with 20mA of 6V direct current, 4 mW of output with 30mA of 6V current, and 6 mW of output with 50mA of 6V current). As a result, different irradiation levels can be achieved. The daily safe dose can be delivered in a shorter or longer allowable exposure time. Using the International Light Technologies’ E275-3 275nm UVC LED as an example, if a net-mounted array of LEDs are arranged above an environment to deliver the daily safe allowable dose of radiation in 8 hours using a current of 20mA to each LED, and the current to each LED is increased to 50 mA, the optical output power essentially doubles, and the daily allowable dose can be delivered in about 4 hours instead of 8 hours. Thus, the same product operated in different modes can give different levels of output.

As a safety precaution, the emitted radiation at various points around the environment can be measured after the emitter(s) have been installed. The number, location, direction, and/or intensity of the emitted radiation to achieve the desired flux at a particular point or points in the room can be adjusted. For example, the average emitted radiation at various points around the room can be measured and the emitters adjusted so that the range of measured emissions at various points around the room or the variance of the emissions measured at various points is below a threshold level. In other words, the emitter output is adjusted to avoid areas with excessively high or low emissions when measured at various places around the room.

Optionally, the system can include motion detectors and/or other monitoring devices under the array of emitters. If no persons are detected under the array, the irradiance output can be greater (e.g., to deliver the daily dose over a 4-hour period of time). However, if motion is detected under the array, a reduced irradiance output is delivered (e.g., to deliver the daily allowable dose over an 8-hour period). Alternatively, the height and/or power output of each emitter or array can be varied according to predetermined rules, such that the array is versatile for a number of different scenarios and installations. In some embodiments, environment 5 can include one or more zoned or partitioned areas that include different levels of germicidal radiation emission. The levels of emission in a particular zone or partition can be stationary and/or can vary depending on circumstances (e.g., the presence of a person in the zone or partition). For example, large retail stores can be configured to emit a general level of radiation through most or all of the environment to deliver a daily dose of radiation withing the maximum allowable occupancy time, say for example 2 hours. However, the environment can also include one or more zones or partitioned areas where less radiation is desired (e.g., a daily radiation dose in 8 hours). These zones or partitions can include unprotected employees, such as a cashiers or pharmacists in an in-store pharmacy. Thus, the store may allow unprotected persons such as customers to enter the store, do their shopping, and checkout, all within the restriction of having to complete their purchases and exit the store in less than two hours, because of the higher levels of emitted radiation throughout the majority of the store. But stationary employees are in areas that are receiving less radiation so they can remain in the area for a longer time.

The differences of emitted radiation in the different zones within an environment in this embodiment can be accomplished in a number of ways. First, the individual emitters above the different zones can be set to emit different levels of radiation. For example, if an environment is irradiated using sixteen ceiling mounted emitters arranged in a 4x4 square array where each emitter is about thirty feet from an adjacent emitter in any direction, a 2x2 array of these emitters (four of them in a cluster) can be set to emit at a higher or lower level of emissions than remaining 12 emitters. The different level of emissions from creates a zone in which there is a different level of radiation being emitted.

In some embodiments, one or more waveguides 50 constructed from metal, plastic, or other materials can be used to direct the output of an emitter onto certain areas. The term “waveguide” refers to a structure that is designed to confine and direct the propagation of emitted radiation from an emitter. One embodiment of waveguide 50 with internal channel 51 is illustrated in Fig. 5. When a waveguide is used, a first area of environment 5 can have a first level of germicidal radiation exposure compared to a second area of the environment that lacks a waveguide or uses a different type of waveguide. Specifically, the use of reflectors and/or adjacent walls can direct visible radiation into a beam directed at a fairly well-defined area. Thus, waveguiding and channeling can be used to create areas where a desired intensity of germicidal radiation is emitted and is different from an adjacent zone in the same environment. The methods can further be used to create a fairly well-defined boundary between where radiation is and is not emitted.

In some embodiments, an environment is irradiated with a single level of radiation above the occupants. Shield 55 can be mounted between the ceiling and occupants, as shown in Fig. 6a. The term “shield” refers to any protective element (e.g., plastic barrier, tent, cardboard, or any other material) that blocks at least a portion of the radiation from emitters 30, thus creating a shadow with less radiation underneath it. In some embodiments, emitters 30e can be positioned on underside surface 56 of the shield (e.g., emitters 30e may emit a lower, higher, or different amount of radiation compared to the emitters 30 positioned above the shield). In some embodiments, shield 55 can include one or more apertures 57 and/or can be constructed from a material that is semi-transparent to germicidal radiation, allowing some (but less than 100%) of the radiation to pass therethrough, as illustrated in Fig. 6b. For example, a retail store can provide radiation levels set so that an unprotected person, say a customer, will receive the full 24 daily allowable dose of radiation in a 2-hour time period. When shield 55 is in place (e.g., about 7 feet above the floor and below emitters 30), the overhead radiation is partially or fully blocked. If the shield is configured to block about 75% of the radiation, an unprotected worker can work under the shield for a full 8-hour workday in this example before receiving a full daily dose of radiation (2 hours for unprotected person / (100% - 75% protection) = 8 hours under the overhead barrier).

In some embodiments, partitioned areas or zones can be created within environment 5 through the use of a plurality of net-mounted emitter arrays mounted and/or operated to create different emission zones in different parts of the environment. For example, a first net-type emitter array can be installed at a first location (e.g., a 9-foot height above the floor over 75% of the area in the environment). A second array can be installed over the remaining 25% of the environment at a second location (e.g., an 18-foot height above the floor). The second array thereby gives a lower irradiance at eye. Alternatively, in the remaining 25% of the environment, a net array could be mounted at the first location (e.g., a 9-foot height above the floor), but emitters 30 configured to operate at higher or lower levels of radiation compared to the first array.

In some embodiments, the environment can include one or more physical barriers. The barrier blocks all or a portion of the radiation crossing the border between first and second zones. The physical barriers can be constructed from any desired material, such as (but not limited to) plastic, metal, cardboard, and the like. In such embodiments, emitters positioned on one side of barrier can emit radiation at a higher or lower level compared to the radiation level detected on the other side of the barrier. Curtains comprising strips of plastic hanging down (“strip curtains”) that are commonly used to separate air-conditioned areas from non-air-conditioned areas can be used to separate partitioned areas or zones for the purposes of having different levels of disinfecting in different areas within an environment. Shelving, displays, curtains, merchandise, etc. can also be used to block germicidal radiation traveling from one zone to another and to allow for the use of different emission irradiances on either side of the partition to create different levels of disinfection. In a commercial airliner, a bulkhead in front of a certain row of seats along with a curtain hanging down in the aisle could provide a physical partition allowing more radiation to be emitted on one side of the partition than the other. This can be very useful where some passengers appreciate the extra air and surface disinfection that the safe levels of UVC emissions can provide in an airplane and are located in one section of the plane; whereas other passengers, who don’t want any radiation emitted, can be located on the other side of the bulkhead.

Environment 5 can provide different levels of radiation in different zones, with the total time limit in each zone being determined and communicated to persons in the environment. For example, if an employee works three hours in an environment with 0.004 W/m ² of 254 nm radiation (accumulating 0.004 W/m2*3 hrs*60 min/hr*60 secs/min = 43.2 J/m ² ), they could work another 3 hours in an environment with 0.0014 W/m ² emissions of 254 nm radiation (60-43.2 = 16.8J/m ² ; 16.8 J/m ² /0.0014W/m ² = 12000 seconds or 3.3 hours). Thus, the amount of time allowable for persons to work or remain in each zone can be clearly communicated. In this manner, employees can interface with customers in a higher-level emission zone with higher intensity disinfection for a portion of their workday, and then work the remaining time of their working day outside the building or in another part of the building with lower or no emissions. Accordingly, workers and customers are protected by emitting higher levels of radiation where it is needed most (e.g., in high traffic areas of the store).

In some embodiments, the system can include a detection element that detects the presence of people in a particular environment or zone. In response, the emission levels can be adjusted as desired by a user. For example, in large retail stores, the racks and shelves include merchandise that forms convenient boundaries that block germicidal radiation and can demark different zones within the store. Germicidal radiation emitters 30b in Fig. 1 can be mounted on top or near the top of the shelving facing downwards in the aisles. One or more detection mechanism (e.g., motion detectors) can be used to detect whether or not there are persons in an aisle between two shelves. If the presence of a person is detected, no radiation is emitted from the 30b emitters mounted in that aisle, or a lesser amount of radiation is emitted from 30b. If there is no detection of a person in the aisle, the emitters can emit a higher level of radiation to disinfect the aisle to a greater degree than would be possible if persons were present. Such embodiments give, on average, a higher level of disinfection to the environment, objects in the environment, and the air within the environment while not exceeding the allowable radiation levels for occupants.

In some embodiments, environment 5 can detect persons in the environment and change the level of emissions in a zone or zones depending on whether or not the zone is occupied by a designated person tracked with a person detection system. The detection system monitors the location of a designated person or persons in the environment and adjusts the level of radiation emitted into the environment in response to the location of the designated person. The term “designated person” refers to a person in the environment whose whereabouts in the environment can be tracked by the system to some extent as they move within the environment. Any person (or every person) in the environment can be a designated person. The persons can be tracked using any conventional method, such as the use of one or more motion detectors, cameras, computer vision monitoring systems, RFID tags, badges, and the like.

In some embodiments, the emittance levels of the germicidal emitters can be adjusted based on the presence of designated persons in an environment or zone. The presence of a non-designated person does not affect the emittance levels (e.g., the levels are not adjusted). For example, in a situation where an environment is being disinfected by multiple emitters mounted above eye level, an allowable exposure time in the environment can be set (e.g., 2 hours). The system requires that all unprotected persons in the environment remain in that environment for a maximum of 2 hours per day, as previously described. Employees in the environment can be identified by the system as designated persons. Customers or passengers entering this environment may not be identified as designated persons in this embodiment. If a customer or any person not identified as a designated person enters the environment, the system may not decrease the level of emitted radiation in response to the presence of a non- designated person. Employees, on the other hand, may be given a wrist band or badge that has for example an RFID identifier on it. As an employee moves about the environment or into zones of an environment, RFID badge detectors positioned in various locations around the store or environment detect the presence of the designated employee and decrease the amount of radiation emitted in that environment or zone. In this manner, a designated person wearing no germicidal radiation protection can be safe in an environment longer than a non-designated person wearing no germicidal radiation protection. The benefits of such a system are that employees and persons who are required to remain in an environment for longer periods of time are kept safe. In addition, visitors and customers who will be in an environment for a shorter period of time are kept disinfected to a higher degree with more intense radiation but are also kept safe from the higher levels of radiation by being required to exit the environment after a shorter period of time.

As set forth above, the disclosed system can be used in a wide variety of environments 5, such as a vehicle. For example, the system can be used to disinfect the interior of a commercial airliner, as shown in Fig. 7. As set forth above, one or more emitters 30 can be positioned throughout the environment (e.g., above the head level of persons in the environment and directed to emit germicidal radiation downward, including directly onto persons in the environment). However, it may also be advantageous in certain situations to position emitters below eye level of persons in the environment oriented upwards, sideways, or downwards. In this way, the entire vehicle interior can be disinfected, including the areas under the seats 65. In some embodiments, an array of emitters are provided arranged to emit disinfecting radiation into the environment and onto persons in the environment. The emitters can be spread out (e.g., in rows or a systematic pattern) to facilitate the uniform irradiance at a desired level (e.g., eye level) in the environment.

As with the embodiments described above in the retail industry, the maximum amount of time that a person can be in the vehicle environment within a 24-hour period is decided. Once the maximum exposure time for the environment or zone within the environment is determined, knowing also the maximum allowable daily dose, the germicidal radiation emission rate or irradiance of the germicidal radiation for that environment or zone can be established as detailed elsewhere, and the emitters can be set and adjusted to give the desired irradiance.

For example, in an airplane the allowable time a person can be in the environment may be determined to be 8 hours. Any desired amount of time can be selected, from a full 24 hours for long overseas flights to 30 minutes for short flights. The maximum daily dose of 275 nm radiation for unprotected eyes and skin is set at 31 J/m ² (ACGIH). 275 nm is the predominant wavelength of output of a typical LED type UVC emitter, the type that will almost certainly be preferred in an airplane. Using emitters of this type, the maximum irradiance of the radiation emitted into the environment or airplane, measured at some predefined height or point in the environment, preferably at eyelevel when either sitting in the seats or standing in the aisle, would be determined by: 31 J/m ² /(8 hr*60 min/hr*60 sec/min) = 0.0011 W/m ² . Thus, emitters in an array formation mounted on or below the ceiling and above persons in the environment would be limited to emit, on average, no more than 0.0011 J/m2 when measured at a level 6-7 feet above the floor or at eye level in the seats. It should be appreciated that other points of measurement can also be used. In this manner, the environment can be freely disinfected with 0.0011 W/m ² of radiation provided that administrative controls are in place to ensure that people do not spend more than 8 hours in the environment in a 24-hour period.

In a situation where crew members work 12 hour shifts and are expected to be in the airplane exposed to emissions the entire time, the emitters can be limited to emitting only 31 J/m ² /(12hr*60 min/hr*60 sec/min) = 0.0007 W/m ² at the designated point of measurement. Since pathogens are disinfected to a greater extent when the irradiance is higher, disinfection will be better and performed to a higher degree if the time that persons are allowed to remain in the environment is shortened. For example, if an airline on domestic flights chose to limit crew and passengers to 4 hours in the irradiated airplane, significantly more disinfecting could be accomplished, and the irradiance could be set higher, at 31 J/m ² /(4 hr*60 min/hr*60 sec/min) = 0.002 W/m ² . Although this may not sound like a significant difference, it will be seen later that this additional amount of irradiance provided by shorter allowable occupancy times can result in a very large improvement in the disinfection achieved for airborne viruses.

In some embodiments, the vehicle can be divided into one or more zones. For example, different disinfection strategies can be employed using germicidal radiation emitters mounted in different areas in an airplane. The different emitter locations can subdivide the airplane into different zones or partitioned areas for emissions, with each zone optionally having a different level of radiation being emitted into it. For example, the vehicle aisle can be included as a first zone with emitters positioned on the ceiling above the aisleway(s) evenly spaced down the length of the vehicle. With an airplane, the emitters can be spaced along the aisle for the entire length of the cabin, about four to six feet apart (or further or closer, depending on the details of the emitter and desired emission levels). In this example, International Light Technologies’ E275-3 275nm UVC LEDs that can output 3mW of optical output power with 20mA of 6V direct current, or 4mW of output with 30mA of 6V current, or 6mW of output with 50 mA of 6V current, can be mounted on the aisleway ceiling spaced say five feet apart. LEDs may be advantageous because they are lightweight, contain no mercury, and are relatively low power output devices compared to mercury lamps. The low power output may be important to allow the low irradiance levels required to meet the safe dose requirements to be more easily met. In addition, the low power output can allow a greater number of emitters to be placed in the environment closer together to achieve a more uniform output.

The output of a E275 LED emitting at the lowest level of 3mW gets close to the low emission levels needed if one were to sit about three feet under the emitter for an 8-hour period. If the emission level is considered too high to be safe with an 8-hour exposure, the emissions from the LED can be attenuated further by covering the emitter with a plastic film, a cover that allows only some radiation through, a partially closed louver, or a screen with openings that block a portion of the radiation. A waveguide surrounding the outer edges of the emitter can also be used to shape the beam of radiation leaving the LED, channeling the light to shine with a spotlight effect (even a square or rectangular shaped spotlight) on the aisleway with minimal light spillage onto the seating on either side of the aisleway. With all of the emitters on and shining downward to the aisleway floor, a barrier of disinfecting radiation is created. Additional emitters can be mounted lower down, such as on the sides of the seats adjacent to the aisle, with the emitters pointed optionally downward toward the floor if desired to enhance the radiation intensity and therefore the disinfecting achievable in the aisleway.

In aisleway 70, the emitters can be evenly spaced on the ceiling above the aisleway and operated in different modes. In one mode, the emitters emit lower levels of UVC at all times, limited, of course, per the methods described herein, to not overexpose any passenger or crew member during flight. In another mode, the emissions from these emitters may be shaped to carefully keep the emissions shining down onto the aisle floor with minimal spillage outside the aisleway. In this second mode, a motion detector is provided with each emitter whose field of view is limited to about the volume of emissions from the emitter; each emitter emits into its own zone in this embodiment. If movement is detected under a particular emitter that emitter emits a lesser amount of radiation, but if no motion is detected, a higher irradiance of UVC is emitted by that particular aisleway emitter over that particular zone of the aisleway. If someone walks down the aisle, into and out of the zones created by each emitter, the level of emissions is alternately decreased and increased as the person moves into and back out of that particular emission zone. The advantage of this embodiment is that the aisleway and air over the aisleway can be irradiated with much more intense radiation when no one is in the zone of the aisleway because passengers and crew will only be exposed to reflected radiation, which will be only a fraction of that originally emitted. Any air passing into the aisleway will therefore be disinfected to a much greater degree than in the first mode described, improving the overall disinfection in the plane in real time with passengers present.

In addition, the body and head area of persons in the vehicle (and the air immediately surrounding the persons) can be irradiated. Particularly, an emitter (e.g., LED emitter) can be installed above each seat or group of seats. The emission from emitters 30 can be shaped to fall primarily on the seat(s) it is intended to disinfect. The emitter can be mounted in any desired location, such as an overhead compartment just above the seat(s), on the back of the seat(s), in front of the seat(s) being disinfected, and/or on the wall of the vehicle. Additionally, in some embodiments, a detection device can be provided to detect the presence of persons only in the seat area that its associated emitter is focused on disinfecting. In this embodiment, if a person is found to be in the seat, a safe level of radiation is emitted onto the person. If a person is not in the seat or group of seats, a higher level of radiation may be emitted onto that seat or group of seats. Determining whether or not there is a person in a seat may be done by motion detection. Alternatively, a visual image can be taken using computer vision technology to analyze the image and determine whether or not there is a person in the seat. However, any method of determining whether or not there is a person in the seat can be used, including sensors located in the seats themselves.

Further, vehicle overhead zones can be treated with germicidal radiation, such as the area above the seats. In these embodiments, a disinfection zone can include an area above the heads of persons seated in the vehicle. Germicidal radiation can be emitted horizontally and upwards, above the heads of persons seated in the vehicle. In an aircraft for example, partitioning of the interior can be achieved by mounting a series of LED emitters horizontally above the windows on the sides of the airplane a set distance from the floor to be above the heads of the majority of passengers when the passengers are seated. The UVC emitted can be shaped to not shine on persons but to shine over their heads. Alternatively, underneath the row of LED’s may be a shelf-like protrusion of stiff plastic, metal, or other material that juts out a distance from the wall, possibly an inch to twelve inches, possibly more or less depending on the emitter and the intended partition or zone that is being created. The protrusion prevents the light from shining downward on persons seated and guides the light horizontally and upward above the heads of persons seated.

The levels of radiation in this zone above the heads of seated passengers may be a higher intensity of radiation than radiation being emitted elsewhere in the cabin. In one embodiment, passengers are told that they should minimize the time they spend out of their seats because they will be exposed to a greater amount of germicidal radiation. The levels of radiation in this area can be set in this above-the- heads-of-seated-persons zone to be for example two or three times more intense than radiation elsewhere in the cabin, and passengers can be informed that they will not be able to be exposed to this level of radiation for more than a certain amount (e.g., about 15 or 30 minutes).

In an alternative embodiment, detectors can be provided that shut off or reduce the radiation emitted from these upper emitters when a person stands up and gets in the line of sight of the emitters. The detectors can be motion sensors, heat sensors, and the like. In some embodiments, the detectors only detect persons when they enter the space above seated persons. In other embodiments, special lenses or waveguides are provided over the LED’s mounted above the windows, and a shelf is not required because the lens and waveguides guide the radiation to keep it from falling on the heads of seated persons. The advantage of such embodiments is to allow more intense (and therefore more effective) disinfection of the air and areas above persons seated in the vehicle without exposing the persons seated to these higher levels of radiation. Persons will primarily only be exposed to secondary radiation from these emitters, which is at a much lower level than that coming directly from the emitter.

In some embodiments, physical partitions or barriers can be installed in the vehicle to aid in the partitioning of the environment. In this way, disinfecting zones that include different levels of disinfecting radiation can be created. The partitions or barriers can be constructed from any of a wide variety of materials, such as plastic or plexiglass plates or sheets, plastic curtains (like thin shower curtains), plastic strip curtains, carboard, paper, wood sheets, strips of metal, etc.

The system can further include emitters positioned in the lower areas of the vehicle (e.g., seat level and lower). In some embodiments, the emitters can be located under the seats emitting horizontally or downward to avoid the eyes of passengers or employees.

In some embodiments, the system can include emitters 30 equipped with person detection or motion detection systems. If a person is detected in within the beam or approaching the beam of germicidal radiation, the system reduces the intensity, redirects, or ceases emitting the radiation. In this way, the person entering the area of the beam is not exposed to unsafe levels of radiation. In some embodiments, no emitters in the environment are intended to directly irradiate persons. Rather, areas where no persons are located are irradiated with higher intensities of radiation. For example, in an airplane cabin, the aisleway can be irradiated with intense radiation when no one is in that section of the aisleway. However, if a person enters that particular section of the aisleway, the radiation is turned down.

In some embodiments, the level of disinfecting radiation or irradiance in at least one zone can be manually or automatically adjusted in response to how the environment is to be used. The adjustment regulates the intensity of the radiation from the emitters in an environment or a zone. In the airplane illustration, a crew member can adjust the radiation level emitted in the airplane to correspond to the flight time and expected time persons will be on board the airplane. The intensity of the radiation or irradiance can be adjusted so that a daily dose of radiation is delivered over the period of time selected. In this way, maximum disinfection can be achieved on every flight by giving each person the daily allowable dose. If the flight time is short, the intensity of the radiation emitted can be higher, and the disinfecting that is achieved on that flight will be better or higher. In the example of emitters emitting 275 nm radiation with a daily limit set at 31 J/m ² , if a flight were to take 3.3 hours, then that length of time is input into the emitter controller. 31 J/m ² /(3.3*60*60)= 0.0026 W/m ² .

As another example, if the flight time is 50 minutes, the system would adjust the output of the emitters for a 50 minute time to a level to give 31 J/m ² /(50*60) = 0.01 W/m ² would be the irradiance at the reference point. The system would be capable of adjusting the output of the emitters to achieve this higher level of disinfecting radiation. The average irradiance over the 50-minute time frame is calculated, and the output can be steady over the inputted time. Alternatively, the system can produce a higher level of output for a set time and then shut off periodically for a few seconds or minutes such that the average emittance over the flight time is at or below the desired level. It will be obvious to those skilled in the art that there will be limits to the adjustments that can be made with the emitter output. However, the maximum possible disinfecting of the persons on the plane (who may not be able to practice good social distancing and may feel very uncomfortable having to sit so close to others on the vehicle) is achieved.

There may be passengers who have connecting flights and may have already received their daily dose of radiation. In such situations, a group of seats somewhere on the vehicle can be reserved where there is little to no disinfecting radiation emitted. The area can be demarked by strip curtains or other physical barriers separating those areas, the emitters over those seats can be turned off, and/or PPE (for example gloves, radiation protective eyewear and head covering, blankets, and other PPE) can be given to these persons to prevent them from being exposed to additional radiation. In this way, the system can accommodate persons who have radiation exposure limitations in an environment where disinfecting radiation is being emitted.

Similarly, the system can be installed in subway cars. As with other environments, the first step is to establish a maximum allowable occupancy time in a 24-hour period. Particularly, it may be determined that 90% of persons ride for less than 84 minutes per 24-hour period. A maximum allowable occupancy time of 90 minutes can then be selected, allowing over 90% of passengers to complete their normal subway travel safely each day.

Emitters 30 can be installed in the vehicle (e.g., subway car) to emit radiation onto a chosen reference point or reference plane (such as 6 feet above the floor for a standing person, or head level of a seated person). The selection of a reference point or reference plane on which the radiation is be measured in an occupied environment is also part of the disclosed system and method. The maximum amount of radiation is determined from knowing the wavelength being emitted and the daily maximum dose for that wavelength. For example, for 254 nm radiation, the daily dose limit is 60 J/m ² . If lamps emitting 254 nm radiation are being used, and 90 minutes is the maximum allowable occupancy time established for the subway environment, the emitters will be set to give on average an irradiance of 60 J/m ² /(90x60) = 0.011 W/m ² irradiance at the chosen reference point or reference plane.

The vehicle authorities can clearly mark and communicate that the vehicle is being irradiated at a level to give each person a 24-hour maximum allowable daily dose of radiation in 90 minutes of travel time, and that each person is fully responsible for keeping track of and limiting their time in those cars to less than 90 minutes. Different subway cars can be irradiated to different levels. Further, the subway can include one or more cars that have no emissions for those persons that have already been exposed to their daily limit. The maximum occupancy time for each car can be clearly communicated on the walls, ceiling, floor, signage, announcements, the like. In some embodiments, a smart phone or watch with a special app can be used to help persons keep track of their exposure to radiation in a particular environment.

Subway cars with a 1 hour or lower occupancy time can be provided for passengers who do not have to travel more than that time on a subway and want the maximum safe amount of disinfecting when they are on the subway. Likewise, subway cars with longer occupancy times (e.g., 2, 3, or more hours) and less disinfecting radiation could also be offered. Thus, the disclosed system and method have a great deal of flexibility for establishing different levels of disinfecting in different occupied environments or zones.

In addition, the presently disclosed subject matter can include blocking agents applied to the user’s exposed skin. The blocking agents can fully or partially block exposure to radiation (e.g., germicidal radiation). For example, the blocking agents can block about 50-100% (e.g., at least about 50, 60, 70, 80, 90, 95, 99, 99.98, or 100%) of the radiation. Specifically, blocking agents such as pigments such as titanium dioxide, zinc oxide, and the like can be added to skin protective coating formulations to block, absorb, or UVC and achieve up to 99.9% germicidal radiation protective capability. Many other organic and inorganic pigments are contemplated, and the safety of the pigment for human skin contact, its ability to block, absorb, or reflect the germicidal radiation wavelengths being used, its colorant attributes, cost, and suitability for formulating it into a skin protective coating all need to be weighed in selecting a pigment to use. Other substances that block or absorb UV radiation such as but not limited to avobenzone, homosalate, octisalate, octocrylene, and oxybenzone may also be considered. However, many commonly used organic UV absorbing substances used in sunscreen products have peak absorptions in the UVB or UVA ranges, since they are formulated for sun exposure, and sunlight does not contain appreciable amounts of UVC radiation. Furthermore, there are safety concerns about the use of organic UV absorbing substances. According to the Environmental Working Group, titanium dioxide and zinc oxide are the only two UVB and UVA blocking substances recognized by the FDA as being both safe and effective.

The terms “skin protective coatings” or “protective skin coatings” or similar phraseology as used herein include any coating applied to the skin for the purposes of protecting the skin from germicidal radiation, including but not limited to creams, lotions, oils, masks, “liquid skin” polymeric coatings, muds, etc.

In some embodiments, persons exposed to germicidal radiation according to the presently disclosed subject matter can be kept safe by providing eye and skin protection for persons. In these embodiments, the level of disinfecting radiation in the occupied environment can be increased to levels higher than would be safe for unprotected persons. Thus, the environment can be occupied by both persons who have eye and skin protection and persons who do not have eye and skin protection, where the allowable occupancy time for protected persons is longer than the allowable occupancy time for unprotected persons.

Protective eyewear is readily available that blocks UVC germicidal radiation, greater than 90%, 99%, or 99.9% (such as Uvex® brand eye protection from Honeywell®). Protective fabrics certified to block 98% of UV radiation are also available (such as those sold by the Coolibar, Inc. shown at coolibar.com). In some embodiments, head coverings can be made in which UV blocking fabric is attached to the perimeter of the UV blocking eyewear and draped down in front of the face and draped back across the forehead, head, back and sides of the head, and neck, as shown in Figs. 8a and 8b. UV- protective fabrics 80 and googles 85 or face shield 90 can be worn to protect the face, head, and/or neck of a user. Workers could wear head covering 95, long sleeved pants and shirt, closed toed shoes, and gloves and be able to work in an environment disinfected with germicidal radiation for extended periods of time and be less limited by the maximum occupancy times for unprotected persons.

The fabrics can be configured to hang down from the eyewear on all sides of the head to the shoulder area to decrease the ingression of germicidal radiation into the face and neck area. The head covering can block at least about 50-90% of the germicidal radiation from reaching the user’s face, head, and neck areas while maintaining comfort and not creating a breathing obstruction. In addition, a fabric that hangs down over the face will also help contain and minimize the spread of infectious disease from sneezes, coughs, breathing, talking, etc. Persons entering an environment protected by germicidal radiation emissions may be required to wear long pants, long sleeved shirts, closed toed shoes and socks, and gloves that cover the wrist area. Persons protected in such a manner would then only need a head covering similar to that described above and shown in Figures 8a and 8b.

For example, in an airplane cabin, crew members can be required to wear the long-sleeved clothing and head gear described above. Such clothing and head gear can be designed to block about 90% of the germicidal radiation emitted into the environment (e.g., a protection factor of 0.90). With such PPE (Personal Protective Equipment), the crew members could be safely exposed to up to ten times the 24-hour maximum dose of radiation for unprotected eyes and skin and still be kept safe. Daily Safe Dose/(100% - 90% protection) = 10 x Daily Safe Dose Allowable Exposure.

On a 2-hour flight, for example, the amount of radiation emitted on unprotected passengers can be set to deliver the entire allowable 24-hour safe dose of radiation in a 2 hour time frame. As a result, a higher level of disinfecting radiation can be emitted in the environment and the passengers are kept within the safe 24-hour maximum window. The flight crew, on the other hand, may have additional flights in their workday. Provided they were the PPE that blocks 90% of the radiation, they can safely continue to work additional flights with the same intensity of radiation. In fact, they could work up to 20 hours in an environment that has germicidal radiation being emitted into it at a rate that would result in an unprotected person receiving the entire daily dose of radiation in 2 hours.

It is also evident that passengers could likewise be required to wear long pants, long sleeved shirts, closed toed shoes, and gloves, and they could be issued or bring with them a head covering that blocks germicidal radiation. If everyone on an airplane was wearing such PPE, the levels of disinfecting radiation emitted into the vehicle can be multiple times higher than the level of radiation that would be safe for unprotected persons. As a result, higher levels of disinfection of airborne and surface pathogens can be achieved, giving persons a greater peace of mind during travel.

In an environment such as a retail store or restaurant, the PPE described above (long sleeved shirt, pants, closed toed shoes, gloves, and head covering) could also be used to enable significantly higher levels of disinfecting radiation to be used while still keeping persons in the environment from being exposed to more than a daily dose of radiation. For example, the allowable time in the environment for unprotected individuals can be set to two hours. Customers entering the store or restaurant would be clearly told that they have two hours to conduct their business and exit before they receive a full daily dose of the germicidal radiation. Workers in the store or restaurant wearing the PPE with head covering that together blocks at least 90% of the radiation would be able remain in the environment for up to 20 hours before they would potentially be exposed to a 24 hour daily safe dose of radiation.

In another example, assume that eye and skin protection is provided to employees that blocks 80% of the UVC radiation, letting one fifth of the radiation reach the eyes and skin. This would allow the emission of radiation at a rate that is five times higher than would be allowed for an unprotected person remaining in that environment for an 8-hour workday would set an allowable exposure time for an unprotected person at 8/5 hours or 96 minutes. Thus, workers in this environment could safely work with the described PPE blocking only 80% of the radiation for an eight-hour workday, while customers or passengers would be limited to being in such an environment for 96 minutes. The benefit is that a significantly higher level of disinfection can be achieved in an environment where protected persons are allowed to stay for longer periods of time. In this way, the system and method for disinfecting environments safeguards both protected and unprotected persons. The system provides for the disinfection of occupied environments for a given exposure time at levels higher than would be allowed if the persons in that environment were unprotected. The system further provides for unprotected or less protected persons to also be in the same environment for a period of time less than the given exposure time of the protected persons.

In some embodiments, environment 5 can include a health care setting as described above. Particularly, a patient’s room in a hospital or nursing home can be disinfected with uniform levels of disinfecting radiation as described previously. If a patient occupies the room for extended periods of time, the intensity of the disinfecting germicidal radiation should be decreased so maximum emitted radiation over the 24-hour period does not exceed a daily allowable dosage.

In some embodiments a frame can be constructed and mounted behind an item of furniture (e.g., bed, chair, sofa, desk, workstation, or any other area to be protected). For example, Fig. 9a illustrates one embodiment of frame 100 configured around hospital bed 105. The purpose of the frame is to help create a partitioned area or zone around the item of furniture. The frame can mount on the floor behind or to the side of the furniture, or to the furniture itself. The frame can include barriers 110, shields, and/or waveguides to guide germicidal radiation toward or away from a desired location, as shown in Fig. 9b. The barriers are intended to create germicidal radiation shadow areas where persons in the bed (or desk, workstation, chair, etc.) are located. The person in the shadow area is prevented from being exposed directly to at least a portion of the radiation being emitted from the germicidal radiation emitters.

Areas outside the shielded areas include greater amounts of germicidal radiation and will receive more direct exposure to germicidal radiation. The device is intended to create a partition within the environment where there is a protected area (or bubble, or shadow area, or volume, etc.) where no or less direct germicidal radiation falls. The protected area will see less, and preferably no, direct radiation from an emitter, and is usually the place where a person is located. One embodiment of this invention is to create a partitioned area within the environment, specifically around the bed (or desk, etc.), more specifically around the head of the bed, into which less or no germicidal radiation is directly emitted, while at the same time allowing higher levels of germicidal radiation to be emitted in the room or environment surrounding the bed (or desk, etc.).

In some cases, it may be desired to have higher levels of radiation in the hallway, for example, where persons are expected to be passing through and staying for a much shorter occupancy time than the adjacent room. The hallway can be considered one emission zone, and the adjoining room the other. If there are doors between the hallway and room, they can be treated as two separate environments when the doors are closed, or they can be treated as one environment with two or more zones if the doors are opened.

The purpose of the system and method is to provide higher levels of disinfecting radiation in an environment around a person that is usually stationary while preventing the person from being exposed to the higher levels of disinfecting radiation. Optionally, the person in one zone of the environment can be exposed to a daily safe dose of radiation while irradiating the surrounding zone(s) to levels that would exceed the daily safe dose. Ideally, only secondary radiation (radiation reflected off of other surfaces) can reach the person inside the protected area. The device also serves the purpose of disinfecting the air around the person so that germs outside the protected area or zone in which the person is usually located are killed at higher rates than germs inside the protected area. The device can be used in situations where the patient has a highly contagious disease or infection and their coughs, sneezes, or talking have the potential to create aerosolized droplets or particles that contain a virus that can spread the infection (e.g., SARS-CoV-2, the virus that causes COVI D-19). As the air containing the virus particles leaves the patient’s immediate area inside the protected area or zone and travels into the adjacent zone with the higher levels of radiation, it is exposed to higher levels or germicidal radiation. In this way, the virus particles are disinfected, and thus the spread of infectious disease is reduced. Another potential application is use with immune-compromised individuals that are highly susceptible to getting sick from airborne viruses. The device will disinfect the environment and air in the environment around the patients to higher levels than would be possible without the device.

If 20% of the radiation is reflected or reemitted from the surfaces of the walls of the room (which can be controlled using special paints or coatings on the surfaces of the walls, ceilings, and floors or installing objects to absorb radiation, etc.), the areas outside the protected area (e.g., around a bed), can be exposed to radiation levels 5 times in excess of what would be a safe dose for an unprotected person, since only 20% of that radiation will reach the person (5 times the safe dose x 0.20 reflection = 1 times the safe dose).

An optional feature can be provided using a location device (such as a motion detector), mounted on the outside of the barrier or shield where the emitters are located. Alternatively, the motion detector or locator device can be focused or limited to viewing only the areas and zones outside of the protected zone where the person is usually located, such as in the bed or at a desk. If a person enters the area outside the protected zone (e.g., a nurse entering the room from the hallway, or if the person in the protected area leaves the protected area), the motion is detected, and the amount of radiation being emitted by the emitters is reduced until the person leaves the room or returns to the protected area or no person is detected outside the protected area.

Another optional feature is the addition of a shield attached to the bed or frame around the bed. The shield can be fully or partially pulled down over the person in the protected area to block out radiation. For example, a radiation blocking fabric tent can be provided on a movable support, with the movable support optionally connected to the frame or shield. The fabric on the support could be pulled down over the patient’s upper body. In some embodiments, the fabric can extend all the way down to the covers to create a better seal against the ingression of germicidal radiation. Alternatively, only a portion of the fabric can extend towards the covers to reduce the amount of radiation reaching the patient. The adjustable shield encloses the person further and prevents excess reflected radiation from reaching the person, which improves the safety of the person (less radiation reaching them). The shield can also allow the radiation levels outside the protected area to be increased even further for additional disinfection outside the protected area. The shield can also create a darker environment to facilitate sleep.

In some embodiments, a radiometer measuring the levels of germicidal radiation can be positioned inside the protected area to measure how much radiation is reaching the patient. Optionally, the radiometer measurement can be used to adjust the level of radiation manually or automatically being emitted outside the shielded area to control the amount of radiation reaching the inside of the protected area. If the irradiance or germicidal radiation reaching the area near the head of the person in the protected area increases, the radiometer will read a higher level of radiation. The emissions in the other zones outside the protected area can be decreased so that the reflected radiation reaching the patient is reduced to safe levels. Conversely, if the radiometer indicates lower than target levels of radiation reaching the patient’s head area, the control circuitry can increase the emitted radiation in the zones outside the protected area until the desired (yet still safe) levels of radiation reaching the patient’s head area is increased. In this way, the patient is not exposed to excessive amounts of germicidal radiation, yet the environment surrounding the protected area is irradiated with as much disinfecting radiation as possible.

In some embodiments, multiple frames with shields and emitters may be used in the same environment. In the example of the hospital bed, a second frame can be used at the foot of the bed to irradiate the environment on that side of the bed and under the bed. The multiple frames can operate independently or be linked together on a single control circuit.

The frames with shields and emitters are portable and can be plugged in to the 110v wall socket for power. Alternatively, they can be permanently installed in areas. In some embodiments, emitters can be mounted overhead in an environment, such as a hospital room. The emitters can be arranged in an array or in a different arrangement and equipped with wave guides, etc. as described above to allow the emitters over the bed to either not emit radiation or to emit a lower level of radiation on the person in the bed. At the same time, the emitters emit radiation at a higher level of radiation in other areas of the room, thus creating a partitioned area or zone of lower radiation directly over the bed. As described elsewhere, person detection systems such as motion detectors could be employed and focused on the partitioned areas outside of the bed, so that if the patient got out of bed and entered a zone with higher levels of radiation, the motion detectors would turn off the radiation or turn down the radiation in these zones outside of the zone over the bed. One could even have multidirectional zones, where a first zone is created around the bed as described above, and a second zone is created with radiation aimed in a horizontal direction to disinfect the air above the bed.

Examples of situations where the device would be useful include office cubicles, to keep the worker in the cubicle safe from radiation while keeping the area around the person disinfected to higher levels; restaurant and other food preparation areas, where customers are exposed to higher levels of radiation for shorter times while the cooking staff is exposed to only reflected or secondary radiation; patients in a hospital or nursing homes; cashiers in retail stores; health care workers, such as nurses at a nurses station (where the station becomes the protected area and the areas around the station are disinfected to higher levels); reception areas or ticket counters, where the receptionist is in the protected area; bus drivers and taxicab drivers located in a protected area; factory workers in designated work areas; waiting rooms and areas, where people waiting for appointments sit in protected areas with higher levels of disinfection taking place around them; emergency room waiting areas; prisoners in a prison where the jail cell is the protected area; a judge in a court room, where the judge sits in a protected area; a resident in a nursing home, where the resident’s bed is the protected area; any area within a home environment can be a protected area, whether a bed, a sofa, a work area, or any portion of a room can be set up as a protected area. In an outdoor environment, workers can set up portable frames and can create disinfection zones around them with protected areas being the areas in which they spend a large portion of their time.

One important aspect of the disclosed system and method includes testing. Specifically, the emitted radiation is tested with a radiometer or other radiation measuring or monitoring device calibrated to detect the wavelengths of germicidal radiation being emitted at one or more locations or emission reference points in an environment. In this way, users can confirm that the desired emission levels are being achieved. Other methods of testing include having individuals wear radiation monitoring devices, such as UV sensing wrist bands made for example by researchers at Granada-RMIT and featured in Optics and Photonics, Oct. 17, 2018. Other monitoring devices include portable or stationary radiometers. Such monitoring devices will give indications to persons in the area when they have been exposed to too much radiation for the day. If persons in the environment are regularly being exposed to too much or too little radiation in their normal work activities, then this invention allows for adjustments to be made to the emitters to reduce or increase the levels of emission from the emitters onto persons in the environment in response to determining that the emitted levels are unsafe or are not intense enough. Testing can occur on a periodic basis, such as weekly, monthly, bimonthly, annually. Further, adjustments, replacements, general maintenance, etc. can regularly be performed to confirm that the radiation levels are within the desired emission levels.

The disclosed method and system are provided to disinfect an indoor or outdoor occupied environment. As set forth in detail above, the disinfection may result in direct exposure of unprotected person(s) to germicidal radiation. In addition, unprotected person(s) are kept safe and prevented from being exposed to greater than allowable doses of germicidal radiation by limiting the emitted radiation or limiting the time a person can remain in the environment to an allowable occupancy time. The disclosed method and system are capable of disinfecting airborne pathogens (e.g., coronaviruses, SARS-CoV-2) to at least a three log destruction level within the allowable occupancy time, at least a six log destruction level within the allowable occupancy time, at least a nine log destruction level within the allowable occupancy time, at least a 12 log destruction level within the allowable occupancy time, at least a 15 log destruction level within the allowable occupancy time, or at least a 20 log destruction level within the allowable occupancy time. (Note: these values are calculated in the following manner. For 254nm UVC radiation, the maximum allowable dose is 60J/m ² . If the airborne SARS-CoV-2 deactivation D ₉₀ using 254nm radiation is found to be a best case of a mere 3J/m ² , then 60/3 = 20 log reduction with a daily safe dose (and this is true regardless of the maximum occupancy time selected). If the airborne SARS-CoV- 2 deactivation D90 using 254nm radiation is found to be more than 3J/m ² , then the number of logs of deactivation that will be achieved with the daily maximum allowable dose will be less than 20 and will be calculated using the same formula “maximum allowable dose / D90 = log reduction achievable with a daily safe dose.”

A system and method of disinfecting an environment is disclosed wherein daily doses of germicidal radiation that enable the impressive results of log deactivation to be increased amazingly further, and that is with the provision of eye and skin protection. In other words, very significant increases in log kill can be achieved when persons in the environment are provided some degree of eye and skin protection. If eye and skin protection blocking 50% of the radiation is provided, then the log deactivation multiplying factor will be 2 (the log deactivation multiplying factor is calculated by 1/((100-% UVC protection)/100). Eye and skin protection blocking 90% of the radiation would allow 10 times more radiation to be emitted into the environment, and therefore the log reduction of airborne SARS-CoV-2 would be 200 instead of 20 in the above example. If protection blocking 99% of the radiation were provided, thereby permitting, if desired, a 100 fold increase in the amount of radiation being emitted into the environment, a log reduction of 2000 would be achieved during the maximum allowable occupancy time. And if protection blocking 99.9% of the radiation were provided, and the radiation levels increased one thousand fold, a log reduction of 20,000 would achieved in the same time period. Although asking people to work in an environment with one thousand times more radiation than would be allowed if no protection was being worn on eyes and skin is probably not practical, the ability to provide eye and skin protection blocking 90% of the radiation and increasing the amount of radiation to a level 10 times what would be acceptable for an unprotected person during the same amount of time is quite conceivable and easily within the capabilities of currently available eye and skin protection. In this way, by providing some degree of eye and skin protection, in an environment and destruction of pathogens in an environment can be greatly enhanced by order of magnitude.

In some embodiments, the presently disclosed subject matter includes the use of higher levels of radiation, up to 1000 times the TLV, in health care environments where patients with extremely transmissible airborne pathogens are being cared for and extreme caution is being used to contain the virus short of having everyone in the area don full PPE protection. For example, COVID-19 patient’s rooms where health care workers and patients are protected using eyewear, clothing, and skin coatings, but with radiation levels low enough such that full suit protection is not required.

Also envisioned is providing a method and system for disinfecting an indoor environment with up to 1000 times the TLV level of radiation during the allowable occupancy time and protecting persons in the environment by either limiting the time a person can spend in such an environment or providing protection and even full PPE protection for persons in the environment that is breathable and comfortable. The problem with many full PPE protective suits is that they are made from materials that do not pass moisture easily and thus body heat from a person in the suit cannot easily be shed. Persons in such full PPE protective suits cannot remain in the suit for periods of time longer than about an hour or two before they become very uncomfortable and possibly begin showing signs of heat stress. Garments and even full protective suits able to block up to 99.9% of germicidal radiation yet still breath and pass moisture are contemplated as part of this invention, specifically garments that can be worn by workers or patients for more than an hour without showing signs of heat stress or other significant discomfort. For example, a suit made from two layers of commercially available and comfortable UV protective fabric, each layer of which is capable of blocking 98% of the UV radiation from an environment, can be constructed. A face shield, goggles, or other UV protective eyewear can be built into the eye and face area, and the fabric can be attached to the perimeter of the eyewear so as to eliminate gaps between the eyewear and the fabric. The fabric can be draped back up over the head and down around the shoulders making a complete head piece that drapes over the shoulders all the way around the person’s shoulders (see figures 8a and 8b.) Underneath this a long-sleeved turtle-neck shirt or shirt-pant combination could be worn. Alternatively, this headpiece can be built into one continuous suit of material, including optionally integrated booties and gloves, and the suit could be donned using a zipper down the front or back. Significant overlap of material at joint areas (e.g., pant to sock or cuff to glove or head piece to chest and back area) can be provided to minimize leakage of radiation and maintain comfort. Thus, the embodiment provides a system and method for disinfecting environments with higher than TLV levels of radiation and providing comfortable protection for persons in those environments to remain in those environments for the duration of the occupancy time. Simple features can be added to the emitting device control circuitry to turn down or off the emissions by voice command or conveniently located off switch if persons wanted to take off their protective clothing for any reason.

EXAMPLES Prophetic Example 1

Disinfecting nurse’s stations and general areas (excludinq-patient’s rooms) in a hospital

The ACGIH has established a daily allowable dose of 275nm radiation of 31 J/m ² . Assuming a workday of 8 hours for the health care workers in a hospital, a maximum of 31 J/m ² will be allowed to fall on the unprotected eyes and skin of health care workers in the hospital in that 8-hour workday. This is chosen for the maximum allowable dose. Dividing 31 J/m ² by 8x60x60 seconds gives an average irradiance of about 0.001 W/m2 to be emitted throughout an 8-hour period. Assuming emitters are mounted as a single LED chip on a 3” disk support (which also provides easy access to power and control terminals associated with the LED wiring) which is then mounted on the ceiling with the output facing downward, and assuming an International Light Technologies’ E275-3 LED emitter, emitting 3mW of 275nm UVC radiation when fed 20mA of 6V DC power, calculations show that at a distance of about 0.9 meters from a point directly below the LED, an irradiance of in the range of about 0.001 W/m ² may be achieved.

Assuming the most vulnerable part of a person is their eyes and exposed skin on their head, and assuming the vast majority of persons are 6.5 feet tall or shorter, a reference plane of 6.5 feet above the floor anywhere in the environment is chosen at which point the emittance measurements will be taken. In this example, the environment will be defined arbitrarily as a nurse’s station, adjoining offices, and the area in the hallway immediately in front of the nurse’s station and ten feet down the hallways on either side. The LED’s are mounted in an array about approximately nine to nine and a half feet above the floor (6.5 feet plus 0.9 meters) shining straight down; in this example the ceiling height will be conveniently assumed to be nine to nine and a half feet above the floor. An emitter array pattern is chosen that is a 5’x5’ square grid with emitter nodes (LED locations) located every five feet in every direction (a 5’x5’ grid is hypothetically chosen for this example as an initial approximation and does not represent actual optimal distances. It is presumed that prior work has been done to either build a computer model to calculate optimal spacing and probable irradiances along the reference plane or that arrays have previously been assembled with these LED emitters mounted at this ceiling height and that from experience it had been determined what spacing gave the optimal combination of uniform irradiance along the reference plane, safety (to not exceed the maximum allowable dose along the reference plane during the maximum allowable occupancy time, and cost of installation and operation. Furthermore, it will be recognized by those skilled in the art that reflected radiation will also play a role in the irradiance levels measured along the reference plane; since every installation will be slightly different in some details related to walls, floors, ceiling, objects in the environment, foot traffic, and other details affecting measured irradiances, etc. will also affect the levels of radiation measured). Since room sizes are seldom lend themselves to being divided into perfect grids, some of the emitter nodes nearer to the edges of the environment (i.e. the walls) are adjusted closer to an adjacent node, say four or even fewer feet from an adjacent node or emitter location. In this manner the ceiling above the defined environment to be disinfected has emitters arranged so that the direct germicidal emissions from the LED’s will intersect the majority, over 80%, of the reference plane. Wiring of this LED array is provided with each emitter in parallel, using drivers and other LED electronic controls as is well-known in the art, along with an on-off switch for the entire array assembly located on the wall somewhere in the nurse’s station.

Once the emitter array is turned on, the emission levels (irradiance) are checked at various points along the reference plane to ensure the desired irradiances are attained. If the desired uniformity of irradiance along the reference plane is unacceptable, means are provided as known in the art (e.g. lenses, covers, wave guides, emittance angles, etc.) to provide shape and direction to each emitter output to minimize higher irradiance readings and increase lower readings. Once all adjustments have been made, a person may be able to walk around freely in this environment under the array of emitters for an entire 8-hour work day or allowable occupancy time and not receive more than a maximum allowable dose of radiation. Prophetic Example 2

Disinfecting nurse’s stations and general areas in a hospital, situation 2 This example is similar in scope to the first example, however in this example the installation team finds that the height of the ceilings are twelve feet. If the same array and procedure is used as described above, the measured irradiances at the reference plane would be significantly lower than optimum, due to the fact that radiation when emitted from a point or line decreases as the square of the distance from the emitter. This in turn would be safer for persons in the environment, but less disinfecting than is permissible would be accomplished. To compensate for this decrease in radiation intensity at the reference plane, several options are available to the installation team. First, they could install more emitters; that is, they can choose an array pattern, say a grid pattern with emitters spaced every three feet apart instead of every five feet apart, that they know from calculations or experience will give them the desired irradiance at the reference plane. Second, they use stand offs or posts mounted on the ceiling and on the bottoms of which are mounted the LED’s to bring the LED height down to the 9-9.5 foot level described in the first example. Third, they could mount the LED array onto a net made of thin, lightweight inconspicuous wires using the grid spacing described in the first example. The net can then be mounted below the ceiling at the 9-9.5 foot level and supported from the ceiling and/or walls. Fourth, the emitters can be mounted on the ceiling at the same grid spacing as in Example 1, however, assuming E275-3 LED chips are used, a higher current is run through the LED elements to provide higher output. If the aggregate current is too high, a small switch could be provided at each LED emitter mount to select the one of three levels of emittance available with those LED’s; simple control circuitry easily performed by those skilled in the art of electronic design would then allow three different levels of output from each emitter node to be selected, and the wiring and controls of the entire array would be designed to allow each node to be operated, based on this switch on the emitter base, at a level of output that may be different from the other nodes in the array. In this way, if there is too much radiation overall coming from the array, selected individual emitters may be turned down in output, or all the emitters may be turned down in output by making this adjustment at each node. This of course need be done once during the initial installation. Other means to adjust the output of each individual emitter to reduce the overall output of the array and/or to make it more uniform may also be deployed, as was described earlier. Covers for each emitter housing at each node may also be provided that have various gradations of radiation blockage. For example, a very crude means of blocking a portion of the light from an emitter housing is to construct a wire mesh cover, where the thickness of the wires used to create the mesh would dictate how much of the radiation leaving the emitter is blocked by the cover. Covers with wire mesh blocking 10%, 20%, 30%, etc. of a particular emitter’s output (or housing output, or node output) can be selected and applied as needed during field installation to help reduce the output of a node.

Prophetic Example 3

Disinfecting nurse’s stations and general areas in a hospital, situation 3 In this example, the nurse’s station is located in an ICU ward or a tuberculosis ward or in an area where highly infectious diseases are being treated. In this instance, hospital administration is concerned about the spread of the diseases and wants to do everything possible to prevent their spread. For this example we will assume that the array described in Example 1 has been installed but that higher levels of emissions are desired. The output of each of the the E275-3 emitters is doubled by increasing the current fed to each emitter, from 20mA at 6V to 50mA at 6V, as described elsewhere. To compensate for this doubling of output, the hospital staff is informed that they will not be allowed to stay in those areas that are emitting radiation, particularly radiation at these higher levels, for more than 4 hours per day for persons who have no eye or skin protection. The 4-hour time limit is clearly communicated orally and in writing to each staff member, markings on the walls and floor are installed to clearly indicate to everyone entering this area that there is a 4 hour maximum allowable occupancy time and that they are responsible for ensuring that they do not remain in the area longer than that. To assist them, area alarms may go off at certain times or individual timers carried on each person may assist them with keeping track of how long they have been in the environment.

Prophetic Example 4

Disinfecting nurse’s stations and general areas in a hospital, situation 4 This situation describes an even more difficult situation than the previous examples in that even higher levels of disinfection are desired, so much so that an unprotected person would only be able to remain in the environment for only two hours prior to the daily dose being exceeded. In this example, the installers of the array have multiple options to increase the output of the array as described earlier. In this situation, they may choose to add emitter elements to each node of the array; for example, instead of mounting one LED on a housing at each node, they could mount housings with two LED emitting elements mounted on each housing. If this were done with the same LED control and output settings described in Example 3, the output of the array would double again. If desired, at some nodes an emitter mount or emitter housing may contain two LED’s, and at other nodes even three LED’s or more mounted on the emitter housing (for example a three inch plastic mounting backet) could be provided, and the overall array output could be regulated in this manner to achieve the desired output as measured at the reference plane. As in example 3, clear markings in the area and communications to the staff and visitors to the area make it abundantly clear to anyone entering the area that they may only be in the area with these elevated levels of UVC emissions for only two hours before they will have received their maximum allowable daily dose of radiation. In this example, it may not be practical for the staff that work in the area to only work two-hour shifts. In this case, the staff may be required to wear additional eye and skin protection that blocks at least 75% of the UVC radiation. This could be accomplished by providing the staff long-sleeved shirts and pants made of comfortable Coolibar® fabrics blocking 98% of UVC radiation, closed toe shoes with socks that also block 98% of UVC radiation, plastic or fabric gloves that block at least 75% of the radiation, and the headwear of Figures 8a and 8b that provides eye protection blocking 99.9% of UVC radiation with comfortable, breathable attached fabrics that block 98% of the radiation. Outfitted with this comfortable eye and skin protection, staff and workers could remain in this environment for more than eight hours, even though the UVC radiation is being emitted into the surrounding environment at levels that would not be safe for a person with unprotected eyes and skin to remain in for more than two hours.

Prophetic Example 5

Disinfecting nurse’s stations and general areas in a hospital, additional zones It will be immediately obvious that environments and the emitting arrays described in Examples 1-4 above can be extended down the hallways and into other areas of the floor or ward. The examples were not meant to be limiting to the size or shape of the environment to be disinfected in any way. Furthermore, different zones could be defined within this environment for different emission levels in any conceivable manner. For example, in some cases it may be desirable to have less disinfecting or no disinfecting occurring in the nurse’s station itself but only in the hallways connecting the various rooms. The logic behind this design may be that persons are less likely to spend time in a hallway, and therefore higher levels with shorter overall allowable occupancy times are allowed. And in places such as a nursing station it may be desirable from an abundance of caution to have less than the allowable levels of radiation being emitted onto persons. In this way, the nurse’s station would be designated as one zone in the environment and the adjacent hallway a second zone. In such situations, the emitting array (or absence thereof) in the nurse’s station may be designed to emit at a lower level than the array emitting in the hallway. Wave guides can be employed, as one example, on the emitters in the higher- level zone to minimize the spillage of direct and secondary radiation into the zone where lower levels of radiation are desired. Those skilled in the art will recognize that without floor-to-ceiling walls separating the nurse’s station from the hallway that there will be some secondary radiation that will spill into the lower level zones and must be accounted for in the overall design by means already described above. In many cases, the installations may involve many adjustments such as those described above once the array is installed in the field to maximize the uniformity of emissions across a reference plane.

Prophetic Example 6 Disinfecting a patient’s room

An array of emitters such as those described above can be installed in a patient’s room also, but in this instance, the fact that the patient resides in the room 24 hours a day requires an array that has a significantly lower output than that described in Example 1, for example. In this example, it is assumed that the ceiling height and array spacing in a patient’s room matches that of Example 1 , however, for the patient’s room, the total irradiance that reaches the patient must be such that the total dose does not exceed the maximum allowable safe dose in a 24 hour period. All other factors being equal, the output of the emitting array of Example 1, if installed in the patient’s room, must be reduced by 2/3, since if it weren’t the patient would receive the maximum allowable dose (given over an 8 hour work shift in Example 1) three times in a given 24 hour period. Thus, the allowable irradiance at the given reference plane would be (0.001 W/m2)/3 or 0.0003 W/m2. The output of the emitters in Example 1 may be reduced using means already described. Other ways of decreasing the irradiance include a) finding other LEDs with lower output, b) covering the LEDs with a semi-transparent film that blocks 2/3 of the emitted radiation and then using the same LEDs and arrangement as described in Example 1, c) turning the emitters off for 2/3 of the time during a 24-hour day (this can be accomplished by any duration of on-off cycles, with the on-off cycles ranging from milliseconds to seconds to minutes to hours, but more uniform emission profiles over time will be achieved with more rapid on-off cycling), etc.

Prophetic Example 7 Disinfecting bathrooms

The same array arrangement of Example 1 can be installed in a bathroom, only in this example eight E275-3 LED emitters can be installed within a few centimeters of one another on a mounting block (i.e. a “cluster” of emitting elements on a single housing at a single node of the array) and the highest current is run through each LED, with each LED producing 6 mW/m ² of radiation. The block of eight LEDs emits the equivalent of sixteen times the radiation as in Example 1. If multiple such blocks of eight LEDs are mounted in an array at the same height and emitter spacing as described in Example 1, they would emit into this environment a level of radiation that is sixteen times the level allowable for unprotected persons to be exposed to in an 8-hour day. One sixteenth of 8 hours is 30 minutes. In this instance, a sign could be placed on the door to the bathroom stating that occupants must not remain in this bathroom or other bathrooms equipped with this level of disinfecting radiation for more than 30 minutes in a 24-hour day and the person entering the bathroom is responsible for ensuring the time limits are adhered to. With such limitations, much, much more disinfecting could be done in high contamination areas such as bathrooms, which usually are not expected to be occupied by any one individual more 30 minutes in a 24-hour day. The level of disinfection achievable would be sixteen times the log reduction of pathogens as if the emissions were maintained as in example 1. Since log reductions of organisms over about 3 or 4 log reductions are difficult for infection control professionals to measure, since there may not be enough pathogens in the air or on surfaces to start with, another way to think of the benefits of this higher intensity emissions is that the time to achieve a one log reduction of a particular organism. In this example the time that it takes to achieve a one log reduction in the number of live or active organisms in the environment will be sixteen times shorter than the time it will take to achieve a one log reduction of the same organism in the array of Example 1.

Prophetic Example 8

Disinfecting passenger airliners, airports, medical facilities, and public areas Previous examples show how different levels of emissions can be chosen for an area once it is known how long persons will be allowed to spend in the area (maximum allowable occupancy time) and the maximum allowable dose. Once these are set and a reference plane is chosen, there are various means as described herein and other means known in the art for achieving that level of radiation in a more or less uniform level of emissions throughout an occupied environment. In this manner, any public place or public transport vehicle may be disinfected with low levels of UVC radiation with persons present. For example, in an airport, a maximum occupancy time of eight hours, including flights, may be chosen and clearly communicated to all passengers. That is to say, all passengers are required to sign a form saying that they understand that they are entering an area where they will be receiving a maximum allowable daily safe dose of radiation in an 8 hour period and that it is up to them to ensure that their flight schedule and airport time does not result in them being in an area more than an 8 hour period. The airlines scheduling their trip can also take note of their overall travel time and issue warnings their total time in airports and airplanes will exceed 8 hours. In a manner similar to that already described, emitting arrays can be arranged throughout the airport to give continuous average emittances equivalent to the 0.001 W/m2 described in Example 1 along a reference plane 6.5 feet off the floor. Persons shorter than 6.5 feet would be safer than taller persons standing upright for the entire 8 hours, since the amount of radiation at levels closer to the floor may be less than at the reference plane. On the airplane itself, very low-level LED emitters may be arranged above the aisle and even on the underside of the overhead compartments, on the sides of the airplane, and other areas and attenuated so that in at no place on the airplane or on any seat on the airplane could a person be exposed to more that a daily safe dose of radiation in an 8-hour total travel time. An alternative to this arrangement would be to not have radiation emitted in the airport but only on the airplane, since that is where people will be in closest proximity to one another and the greatest concerns about contracting a disease will occur. For persons who do not want to be exposed to any radiation, there can be areas on the airplane and in the airport, different emissions zones, that have no radiation emitted. Alternatively, passengers can be asked to bring or can be provided clothing and headwear as described for health care workers in Example 4 above, which would allow them to remain in the environment safely for much longer periods of time. With airborne coronaviruses, even these low levels of emissions will give a significant amount of disinfection, as described earlier. The maximum allowable occupancy time could, of course be set longer if desired, say to 12 hours or even 24 hours for overseas flights and airports where travelers are expected to spend extended periods of time. But even at these very low levels of emissions, noticeable and significant log reductions of airborne coronaviruses can be achieved in this period of time, as is shown in Figure 10 and described in the spec. Obviously, these same levels of radiation can be useful in hospitals and any public areas to provide ongoing, safe, low levels of disinfection.

Prophetic Example 9

Disinfecting hallways in health care facilities

A final example is provided in which more intense disinfection of hallways, particularly in hospital and health care settings, is provided. Hallways can be equipped with a linear array (emitters oriented in a one-dimensional straight line) of emitters similar to those already described in earlier examples, on the output of the emitters in the array can be much more intense than that described in previous examples, perhaps comparable to the bathroom disinfection example where each node of the array emitted 16 times the UVC output as a node in Example 1, or even higher levels of emissions. The difference in this example is that each node is also equipped with a motion detector set to detect whether or not there is movement within the emission volume of the emitter node. If no, then the emitter node emits at the high level of radiation. If motion is detected, then the emitter turns off the emissions from that mode until say five or ten seconds after the motion is no longer detected (any length of time could be selected). In this manner, an empty hallway has all emitters in the linear array emitting a full, intense amount of radiation at a level that would not be safe for persons to be in for an extended period of time. However, as the presence of a person walking through the hall is detected, the emitters shut down to minimize exposure of the person to the radiation. The motion detector(s) can be set to turn off or turn down only one emitter or multiple emitters in the line. In this manner, the disinfection of the hallway is optimized, with higher levels being achieved when no one is present and lower, safer levels being achieved when persons are present. Due to reflectance and secondary emissions, the actual design of such a system may have to be done by actually building the system, which should be straightforward to those skilled in the art, and determining what are the appropriate emission levels, cut off times, etc. to keep persons walking down the hallways safe. But the benefits are higher levels of disinfection of the air and surfaces in a health care facility and a lowering of the reservoirs of pathogens overall. This concept of course can also be applied not only in hallways but rooms and other environments.