FIELD OF THE INVENTION

The present invention relates to a smog filter, for filtering by adsorbing and absorbing the harmful components and reducing the harmful effects of smog inhaled, the filter containing natural materials only.

Specifically, the invention relates to a new smog filter, capable of binding by adsorbing and absorbing solid smog-particles, water, nitrogen oxides (NOx) and other free radicals (ROS).

More specifically the invention relates to a smog filter containing antioxidants and alginite of natural origin having not been applied in this special field before.

Particularly the invention relates to a smog filter containing alginite and antioxidants, where the antioxidants are selected from beetroot, carrot granules, red grape pip and skin grist (RGPSG) or any combination of mixture thereof, for use as refills for masks, air filters in vehicles and air conditioner devices.

More particularly, the present invention relates to a smog filter, which can be used also for inhibition of infections on the mucosa of respiratory organs caused by pathogens such as viruses, including SARS-COV-2 virus.

In a special embodiment of the invention the smog filter is a cylindrical cartridge filter.

The filters according to the invention can be used advantageously as refills for masks, and as air filters of air conditioners or as air filters in vehicles, e.g., cars, buses, trams, trains, and airplanes.

TECHNICAL BACKGROUND

Air pollution is comprised of a highly complex mixture of gaseous and particulate components. One of the main components of air pollution is the smog of photochemical origin, being the result of a free radical chain reaction mechanism, which involves nitrogen oxides (NOx)and hydrocarbons. NOx and unburned hydrocarbons are key ingredients in the formation of smog, a condition that afflicts an increasing number of cities. NOx radicals constitute an important family of air polluting chemical compounds. Most of the NOx radicals are produced naturally on basis of microbiological action, however an important fraction of NOx radicals is generated by anthropogenic processes. The most important artificial sources are transport (~ 75 %), and industry (-25%).

Industrial processes and those concerned with energy production, i.e., the burning of coal, oil, and gas, electroplating, and metal production processes, forest fire, lighting, and decaying vegetation are responsible for generating the largest part of NOx. The main adverse effect of NOx is the destruction of stratospheric ozone. This process contributes to an increasing greenhouse effect, emergence of acidic rain and generation of photochemical smog.

Precisely, the term "nitrogen oxide compounds" (NOx)includes seven compounds: nitrous oxide (N ₂ O), nitric oxide (NO), dinitrogen dioxide(N ₂ O ₂ ), dinitrogen trioxide (N2O3). nitrogen dioxide (NO2), dinitrogen tetroxide (N2O4) and dinitrogen pentoxide (N2O5). Since NO2 is the most prevalent form of NOx, it is generally accepted that NO2 represents NOx.

Smog formation involves several possible reactions, however the initial event in the production of a hydrocarbon free radical, i.e., a hydrocarbon with an unpaired electron in the place of the bond to the hydrogen atom. Radicals in free forms were recognized by Gronberg ¹ . who discovered the relatively stable triphenylmethyl radical. Hydrocarbon free radicals can be produced by the interaction between ozone and car exhaust gas hydrocarbons.

Hydrocarbon free radicals rapidly react with oxygen to form a new free radical containing two oxygen atoms. One of these oxygen atoms is readily donated to nitric oxide, producing nitrogen dioxide, and creating another free radical HO2 in the reaction, which can donate an oxygen atom to another the nitric oxide molecule leaving a hydroxy radical HO. This radical is extremely reactive. There is sort of chain reaction that leads to the rapid building up of smog production.

It is well known that free radicals are dangerous for human health when the antioxidant capacity of the body is reduced, leading to a disturbed balance in the redox chemical processes. This status causes many abnormal biochemical transformations. The oxidative stress triggered by external free radicals plays a significant role in many diseases. First of all, the free radicals of smog getting into the lung may reduce the resistance to infections, may lead to shortness of breath and irritate the upper airways, in people with lung disease (for example as asthma and obstruction) being one of the reasons of cardiovascular diseases, atherosclerosis associated with aging processes, diabetes and cancer ² . Free radicals act also indirectly as cellular messengers and elicit an inflammatory response. Higher concentration of these species may cause oxidative modification of biological molecules. Elevated levels of reactive free radicals initiate lipid peroxidation and accumulation of lipid peroxides in the sperm membranes causing a reduction in sperm motility and viability causing infertility. Overproduction of free radicals is also an initiator of cataract, liver diseases and have been implicated in pathology of several neurological disorders (Parkinson disease, Down syndrome, Alzheimer disease) as well.

Therefore, the development of methods and devices, suitable for the elimination of dangerous free radicals from the environmental air remain very important. Industry generally produces potentially polluting gaseous flows which must be treated before the emission into the environmental air. For the reduction of the amount of polluting gases - including NOx - numerous systems have been developed. Such a complex system is the Condorchem Envitech ³ technology. The DeNOx ^R process, patented by Condorchem Envitech was conceived for the treatment of the emission from power generating solar thermal plants, by converting the NOx pollutants into products reusable in solar thermal plant processes. The system involves other methods as well: gas scrubbers, biofiltration, adsorption (activated carbon, zeolites, alumina), regenerative thermal oxidation, recuperative thermal oxidation, catalytic oxidation, rotary evaporation, photooxidation, selective catalytic reactions, cryo-condensation.

Other materials e.g., TiO ₂ , are also used for removing NOx. The broad optical band gap of solid state TiO ₂ enables it to be a useful photocatalyst in the ultraviolet region of the spectrum. By oxidation to nitrates ⁴ a clean TiO ₂ surface in the presence of sunlight therefore enables the removal of harmful NOx from the atmosphere.US 10639614B2 published on May 5, 2020 (Tronox LLC, Cristal Usa Inc.) discloses non-NOx reducing coatings and methods for reducing NOx ⁵ . Several other sorption methods (both adsorption and absorption) are also used for reducing NOx concentration. For example, according to such a method dry powdered limestone is sprayed into the fluid gas. Yet another process applies carbon injected into the air flow to finish the capture of NOx radicals. Sorption is reported to have up to 60 % efficiency ^6-7 . There are many adsorbents and absorbents available for capturing NOx under industrial circumstances.

It iso obvious that TiO ₂ and many other adsorbents are not suitable for direct human use e.g., in face masks. However, activated carbon and later also fibrous polymers proved to be useful for the adsorption of smog components e.g.. NOx.

Activated carbon, invented by Raphael von Ostrejko originates from 1900. In 1920 the demand for activated carbon continued to expand through the extensive application of gas masks rendering activated carbon a universal adsorber. Several firms offer different type of activated carbon (one of the biggest being the Jacobi group ⁸ ). They produce different types of activated carbon such as granules, powders, pellets, having different structural and textural properties as well as functional surface groups, which result in different affinities to NOx. Activated carbons are prepared generally by physical and chemical activation. Water vapor as a physical activator provides the best adsorption capacity which is most probably due to the activated carbon as a smoother surface. There are activated carbons modified with reactive compounds, such as metal salts, acids, and amines to enhance the adsorption of different chemicals ^16-17 .

There are many types of active face masks in the market e.g., Jacobi ⁸ products. Amazone ⁹ active carbon face masks, Airium ¹⁰ urban air masks, Merck ¹¹ masks.

The air filter masks use generally multilayer technology to provide superior protection against different particles and hazardous airborne substances.

Common plastic filter materials are PP (polypropylene) PAN (polyacrylonitrile), PVDP (polyvinylidene fluoride), PET (polyethylene terephthalate). However, PET and PP are hardly biodegradable.

Soybean proteins constitute one group of actively used biomaterials due to their low cost and good processability. In many studies soy protein was electro-spun to form nanofibers and the produced nanofibers showed good filtration performance against solid particles and smoke ^12-13 . Soybean proteins therefore seem to be suitable for making eco-friendly, biodegradable, recyclable, or reusable filters.

The internationally accepted NOx level established by EPA (Environmental Protection Agency US) - representing a standard for NO ₂ levels - is 0.053 ppm(100pg/m ³ ) as an annual arithmetic mean concentration. This NO ₂ level fulfills the requirements of air quality necessary to protect public health.

STATE OF ART

The closest prior art. International Publication No. WO2017/18107211 ¹⁴ (partly the same inventors) discloses that carbon a grape pip and skin grist and alginite mixture is especially effective when used in cigarette filters resulting in significantly less ROS in saliva, in blood serum, less endothelial damage and less lung epithelial damage. As a main difference, the solution disclosed therein is directed to a new solution, since the depth and frequency of breathing, and the composition of the inhaled air compared to cigarette smoke is entirely different. In the solution disclosed in WO2017/18107211 ¹⁴ water-binding played a much more significant role, since during smoking, water is released, and therefore, alginite as water binding component had much higher importance.

A highly efficient cigarette filter is described in WO2010/125412 ¹⁵ . This cigarette filter comprises in addition to common components of the cigarette filters pseudo boehmite (AlOOH.H ₂ O), and grape components, astaxanthin and cranberry as antioxidants. The advantageous effect of the cigarette filter is also due to the use of the grape components in grape pip and skin grist form. WO 2010/125412 is herewith incorporated in its whole content as a reference.

AIM AND SOLUTION ACCORDING TO THE INVENTION

As mentioned before, air pollution and various viruses are a great potential danger for human health, and further, considering that masks containing activated carbon, or made of polyesters, rayon or cotton are often ineffective against air pollution, the development of methods and devices, suitable for the elimination of dangerous free radicals and pathogens from the environmental air remain very important. Accordingly, the aim of the invention is to provide a smog filter for reducing the harmful components and effects of the smog in inhaled air contributing thereby to a higher level of prot ection against air pollution and pathogens.

The inventors found that the aim of the invention can be readily achieved by a smog filter according to the present invention.

Accordingly, the invention relates to a novel smog filter capable of binding NOx and other ROS and providing pathogen protection, the filter comprising only eco-friendly, biodegradable, and low-cost materials of natural origin, having not been used in this special field before.

As material of smog filter according to the present invention an alginite-RGPSG combination has been used for filtering inhaled air and thereby reducing the number of harmful components, like for example NOx and other free radicals (ROS) reducing the chance of infections caused by various pathogens including viruses.

Binding of NOx and other ROS with a smog filter of the invention has not been disclosed before. According to the present invention in addition of RGPSG and alginite, and natural antioxidant components (beetroot, carrot) can be used in the smog filters in different combinations for binding NOx and other ROS. The experiments revealed that there is also a synergism between the components, and accordingly the solution of the present invention is not only novel but is based on inventive activity as well.

As a special embodiment of the smog filter the invention relates further to a cylindrical cartridge filter for use as refill for masks, air filters in vehicles, and air conditioner devices.

DETAILED DESCRIPTION OF THE INVENTION

The invention relates to a novel smog filter which - in a special embodiment of the invention - may also be in the form of a cylindrical cartridge filter. The filter of the invention contains natural materials for example beetroot carrots granules, red grape pip and skin grist (RGPSG) and alginite in different combinations for use as refills for masks, for air filters of vehicles and air conditioner devices.

The present invention preferably uses a single carrier mask having a receptacle for a replaceable filler cartridge. Said carrier mask is preferably designed in such a way that the filters according to the invention can be inserted into it.

Any of commercially available carrier masks can be used to be equipped with the cartridge filter insert according to the subject matter of the invention,

The carrier mask is preferably capable of accommodating two filter cartridges, however, masks with space for one cartridge only can also be used without any loss of filtering capacity. It is clear for a person skilled in the art that in such cases the filter insert according to the invention must be modified accordingly.

For the solution of the subject matter of the invention carrier masks with two receptacles and two filter cartridges per carrier mask have been used. The filter cartridges were cylindrical cartridges according to a preferred embodiment of the present invention; however, the form of the cartridges is not limited thereto. As it is readily understandable for any person skilled in the art the shape of the filter cartridges according to the invention may vary according to the form and volume of the receptacles of the carrier mask.

Due to the limited surface of the carrier mask (adjusted to a normal human face area) the size of the cartridges must be adopted accordingly. Therefore, the diameter of the cylindrical cartridge should preferably not exceed 30-40 mm and the height should not exceed 15-20 mm. Considering the above the insertion of a total charge of about 10-14 g is possible for one carrier mask. It must be stressed that for achieving the aim of the invention different charges with different sizes can be applied, the amount and volume of which can be readily determined by a person skilled in the art.

According to the closest prior art a particle size of 0.2-0.4 mm and as material a cellulose acetate-arginite-polyphenol construction are used as particle sizes and component of the subject matter of invention, of a cigarette filter.

Compared to the closest prior art according to the subject matter of the present invention preferably a larger 0.6-08 mm particle size has been used. The increase in the particle size is necessary to ensure lower air flow resistance during breathing because the components and the sizes in the smog in normal air are completely different from those comprised in cigarette smoke.

A particle size below this range is not advantageous due to the great resistance of air inhalation because the small particle size inhibits the normal breathing and a particle size exceeding the upper limit can lead to the decrease of effectiveness, because the smaller sized harmful components of the smog will be not filtered.

As mentioned above, according to the present invention for practical reasons the diameter of the cylindrical cartridge should preferably not exceed 30-40 mm and the height should not exceed 15-20 mm, although also cartridges having a larger size can be used.

Materials and methods

As natural components, the filter of the invention contains beetroot, carrot, red grape pip and skin grist (RGPSG) and alginite. Said components will be discussed in detail below.

- Beetroot (Beta vulgaris L)

The beetroot is a valuable, traditional, and popular vegetable also for use in dried form in the food industry. Beetroot has a fiber structure and comprising a high number of biologically active substances such as carotenoids, glycine, betaine, saponins, betacyanins, folates, betanin polyphenols, flavonoids, B vitamins (B1, 2z, B3, B6) ¹⁸ . Beetroot is also a significant source of polyphenols having a high antioxidant effect and radical scavenging capacity ^19,20 .

- Carrot (Baucus carota L.)

It is well known that carrot is one of the most important cultivated vegetables in the world. Carrot has dietary fiber and high level of several other functional components, bioactive substances such as anthocyanins, polyphenols, P-carotins, carotenoids, carbohydrates, B vitamin complexes and amino acids, and has also good antioxidant properties and free radical scavenging activity. ²¹ - Red grape pip and skin grist (RGPSG)

The red grape pip and skin grist (RGPSG) contains different type of polyphenols (tannin phenols, non-tannic phenols, flavonoid polyphenols, non-flavonoid polyphenols, procyanidins) as antioxidants having a high free radical scavenger activity.

- Alginite

Alginite is a natural organo-mineral material in the Pannonian lakes system (Hungary) existing already about4 million years ago in algae form. Due to volcano eruptions algae together with eroded rocks formed a continuous sediment. Alginite is a neutral, nontoxic material containing a relative high number of organic substances, like biogenic and trace elements but comprising no harm fill elements. It has a high adsorption capacity and therefore has potentially high affinity for binding smog components, for example solid particles and water.

Mechanism of the polyphenolic antioxidant effect

It is known that free radicals are molecular or aromatic species having unpaired electrons. Most free radicals are very reactive with oxygen although there are also exceptions like for example oxy radicals.

Oxy radicals belong to the class of free radicals where the unpaired electron is located predominantly on an oxygen atom. Free radicals are usually extremely reactive and can inflict considerable damage to biomolecules, which may lead to serious biological consequences as well as to various pathological disorders. The antioxidants are capable of elimination this harmful effect.

Red grape antioxidants are inhibitors of initiation of free radical processes as metal - complexing agents and operate as chain-breaking antioxidants ²² . The antioxidant compounds of beetroot and carrot belong to the group of chain-breaking antioxidants. Polyphenolie antioxidants react with oxyradicals according to the following reaction scheme (wherein “Ar” is an aromatic compound): Usually, only the overall process is indicated as

According to the above the antioxidant components according to the invention (beetroot, carrot and RGPSG) can bind all free radicals beyond the oxidative free radicals as well.

Analysis of the polyphenol content of beetroot, carrot and RGPSG preparations

For the analysis 25 g of beetroot preparation was extracted with 100 cm ³ 80 % (v/v) ethanol (24 hours). 25 g carrot was extracted with 100 cm ³ of 70 % methanol (1 hour), both extracts were filtered and centrifuged at 1200 g for 15 minutes, The total polyphenol extraction was carried out by ethanol 60 % (17 hours) from 5 g RGPSG granulate.

Each 200 μl of beetroot, carrot and RGPSG extract was added to 1000 μl Folin- Ciocalteau phenol ²³ reagent (1:10 v/v aqueous solution) and then mixed with 800 μl of 7.5 % (v/v) aqueous sodium carbonate solution. After incubation at room temperature for 120 minutes, the absorbance of the mixed solutions was measured in LTV- VIS spectrophotometer at 750 nm using the respective solvent as blank, The polyphenol content was expressed as mg gallic acid as standard.

FIGURE 1 (Table 1):

The polyphenol content of the granulated natural materials is summarized in Table 1.

The values disclosed in Table 1 depend on the variety and location of the plants.

Determination of Oxygen Radical Absorbance Capacity (ORAC)

Measurements were carried out by benzidine assay ²⁴ . This method utilizes an oxyradical generating system (hydrogen peroxide and horse radish peroxidase) and an oxyradical- sensitive chromogen, benzidine. In situ generated oxyradicals react with the chromogen to give an intermediate compound with an absorbance peak at 620 nm detectable with LKB Biochrom 4050 ULTROSPEC UV-VIS spectrophotometer. Antioxidants present in the sample compete with the chromogen in the oxyradical reaction and inhibit the generation of blue color. By comparing the absorbance of the samples with the control (having no antioxidant present) or to a control having a defined antioxidant concentration, the antioxidant concentration of the samples can be determined.

Reagent A (dissolved in distilled or deionized water)

- 155 mM sodium chloride (Reanal. cat. no. 24640-1-088-38)

- 9000 U/L horseradish peroxidase (Sigma ^R , cat. no. 77332)

- 233μM benzidine dihydrochloride (Sigma ^R , cat.no. B3383)

Reagent B (dissolved in distilled or deionized water)

- 250 μM urea-hydrogen peroxide (Sigma, cat.no.289132)

Assay procedure: 1.0 ml of reagent A was mixed with 20 μl of extracted sample in the photometric cuvette and the reaction was started by adding 200 μl of the reagent B. Measurement of the sample absorbance started immediately and the absorbance value was recorded after 3 minutes at620 nm wavelength. Absorbance of the samples without antioxidant represented the value of 100 % oxyradical content. The scavenging effect of the antioxidant is linear till 2.5 mmol/L ascorbic acid concentration value.

In the assay the following combinations of antioxidants were used:

- beetroot alone,

- carrot alone,

- RGPSG alone, beetroot-RGPSG (50-50% (w/w) combination), beetroot-carrot-RGPSG (at amass rate of 1/3-1/3-1/3), RGPSG-beetroot-carrot-alginite (30-30-30-10% (w/w) combination), RGPSG-alginite (50-50 % (w/w) combination)

We note that the above combinations were used as exemplary preparations for the proposes of proving the efficacy of the invention. It is obvious for a person skilled in the art that the aim of the invention can be readily achieved with different combinations as well, said combinations belonging also into the scope of the present application.

FIGURE 1 (Table 2):

The scavenging effect of the antioxidant is linear to 2.5 mmol/1 ascorbic acid.

TABLE 2 represents the oxyradical binding (adsorption) capacity of the different combinations of antioxidants and alginite used in filters according to the invention.

As reference. 100 ml ascorbic acid solution was used (60 mg ascorbic acid dissolved in 100 ml water solution).

Model experiments on NOx binding capacity of beetroot, carrot, RGPSG and with alginite mixed materials in different combinations

Preparation of the filter material

Preparation of beetroot for cartridge filter

Beetroot was washed and sliced up in a suitable crusher, (length - 2.5 mm, thickness -4 mm) dried at 60° C. The material thus obtained was grinded and a fraction having a particle size of 0.6 - 0.8 mm was separated by using a vibration sieve. The remaining pulver was granulated with CMC (carboxymethylcellulose, 5 % water solution) particles dried and separated of the fraction 0.6 - 0.8 mm with help of the vibration sieve. The polyphenol content and ORAC of the preparation were determined (see above).

Preparation of carrot for cartridge filter

Carrot was washed and sliced up in a suitable crusher (length ~ 2.5 mm, thickness ~ 4mm) dried at 60° C. The material thus obtained was grinded and a fraction having a particle size of 0.6 - 0.8 mm was separated by using a vibration sieve. The remaining fine grist was granulated and separated as before. The polyphenol content and ORAC of the preparation were determined (see above).

Preparation of RGPSG for cartridge filter RGPSG was dried, grinded and 1000 g of grist was granulated with 330 g of concentrated aqueous red grape skin extract (dry material content: - 35 - 40 %). The material thus obtained was grinded and a traction having a particle size of 0.6 - 0.8 mm was separated by using a vibration sieve. The polyphenol content and ORAC were determined (see above).

Preparation of alginite for cartridge filter

Alginite was grinded and a fraction having a particle size of 0.6 - 0.8 mm was separated by using a vibration sieve, then activated at 110 °C (5 hours)

FIGU RE 2 represents the schematic form of the experimental arrangement of the cartridge.

Compositions of the active filter material:

- carrot granules alone

- RGPSG alone

- beetroot alone

- beetroot + RGPSG50 - 50 % (w/w)

- beetroot + carrot + RGPSG 1/3-1/3-1/3 (weight ratio)

- beetroot + carrot + RGPSG-alginite 30 - 30 - 30 - 10% (w/w)

- RGPSG- alginite 50 - 50 % (w/w)

The particle size was 0.6 - 0.8 mm.

FIGURE 2 also represents the diagram of the equipment used for determination of NOx binding measured with the compositions of the invention

EXAMPLES

The invention will be demonstrated by the following non-limiting example. Example 1: Measurement of NOx adsorption

Materials: Nitric acid (HNO3.65 %, aq), Zn powder, reagent Griess - Ilosvay Devices: air bottle, flow measuring apparatus, LKB Biochrom 4050 ULTROSPEC UV- Vis spectrophotometer, calibrated micro pipettes, semi-micro cuvettes

Composition of the Griess --- Ilosvay reagents:

Reagent A: 1 g of sulphonic acid dissolved in 100 ml acetic acid (30 % water solution) Reagent B: 0.3 g of a -naphthylamine dissolved in 70 ml hot water. After cooling 30 ml of concentrated acetic acid was added to the solution.

For the experiment 1:1 (volume ratio) rate of reagents A and B was used in the reaction of NO ₂ .

15.0pl (9.7 mg) HNO ₃ was injected into a closed experimental apparatus containing 100 mg Zn powder, The NO ₂ gas produced in the equipment was led through the cartridge of the invention. The cartridges contained 5,0 g charge of the filter materials or material combinations mentioned above (beetroot alone, carrot alone, RGPSG alone, beetroot- RGPSG 50-50% combination, beetroot-carrot-RGPSG at a mass rate of 1/3-1/3-1/3, RGPSG-beetroot-carrot-alginite30-30-30-10% (w/w) combination, and RGPSG- alginite 50-50 % (w/w) combination) at a flow rate of 500 ml/min. This rate corresponds to the normal human respiration rate. Non-absorbed NO ₂ produced a red color in the liquid absorber containing the Griess - Ilosvay reagent (12ml). The color intensity was measured in the spectrophotometer at 540 nm wavelength. The results of the measurements were compared to the results obtained with an empty cartridge.

FIGURE 3 (Table 3):

The data of NO ₂ absorption measured on different cartridges in model experiments are represented in the TABLE 3.

The results clearly show that the RGPSG-beetroot-carrot and RGPSG-beetroot-carrot- alginite compositions exhibit the highest adsorption capacity which also definitely proves the synergy between the components. Determination of the efficacy duration of the cartridges of the invention

It is generally accepted that NOx pollution may exceed a concentration of 200 μg/m ³ under extreme conditions (for example in densely populated areas with high traffic). Using the 200 μg/m ³ concentration value as a basis of our calculation 9.7 mg NO ₂ is present in 48.5 m ³ air (see the experimental value in Table 3). As a physiological fact, an average human inhales 0.5 liter of air per breath which corresponds to 8 l (liter) air per minute and 11520 1 per day which corresponds to 2.304 mg of NOx/day. The experiments showed that the cartridges of the invention are capable of adsorbing 6.3 - 8.2 mg of NOx which corresponds to an effective operating term of 2,7 - 3,55 days.

The compositions of the invention defined above are exemplary embodiments of the compositions falling into the scope of the present application. It is readily understandable for a person skilled in the art that the compositions can be easily amended in a way still to achieve the aim of the invention. The scope of the invention extends to all such amendments and amended compositions.

Summary

The invention relates to a novel smog filter for use in binding NOx and other ROS and providing pathogen protection comprising eco-friendly, biodegradable, and low-cost materials of natural origin, which have not been used in this special field before.

The smog filter of the present invention uses alginite-RGPSG combination for filtering inhaled air and thereby reducing the number of harmful components, like for example NOx and reducing the chance of infections caused by various pathogens including viruses.

Our experiments clearly demonstrated that beetroot, carrot granules, RGPSG, alginite and their combinations can adsorb a significant amount of harmful NOx and tree radicals present in the environmental air. A further advantage of the filters of the invention is that their filtering capability extends also to pathogens which might help in preventing infections (for example virus infections caused by SARS-COV-2 viruses). The components used in the filters of the invention are of natural origin, do not contain harmful chemical compounds and their use is highly cost-effective.

The experimental data clearly shows that the three-component system consisting of beetroot, carrot granules and RGPSG and the four-component system consisting of beetroot, carrot granules, RGPSG and alginite exhibit the highest efficacy, and comparing the respective measurement data with those obtained with the single components of these systems reveal that a synergistic effect between the components exist. Alginite is significant in air filtering due to its capability of adsorbing solid particles and water from the smog. The results obtained with the filters of the invention proves that face masks equipped with the filters are capable of efficiently decreasing the harmful health effects of smog and may also contribute to the protection against pathogens

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