To provide an exhaust fan system and a method of operating the exhaust fan system capable of suppressing movement of a gas between a space around an exhaust device and a space outside of the space, forming an air curtain of long range by reducing interference of an exhaust flow and the air curtain, and efficiently discharging the exhaust.

This exhaust fan system includes the exhaust device having a roughly-rectangular suction port for sucking the gas in the exhaust space, and an air blower having a discharge port for discharging a gas for forming blocking flow for suppressing the movement of the gas between the exhaust space and the external space outside of the exhaust space. The gas forming the blocking flow is discharged from an upper part with respect to the suction port to the degree not interfering with the suction flow sucked to the suction port, and discharged obliquely downward to the degree not interfering with the suction flow.

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