Heat as a means of air purification

These studies support the view that high-temperature heaters, such as the ceramic-type incandescent electric heater, exert a considerable bactericidal and sporicidal effect. When in operation in the home, the rates of reduction of air-borne micro-organisms generally are of the order of 50 per cent per hour for the more resistant spores. Where these electric heaters are the principal source of heat for a given home or room, it is reasonable to expect that the micro-organism content will reach a very low level after several hours of operation. It is clear that a considerable portion of the air circulating around the heater may not soon pass close enough for the organisms contained therein to be destroyed. It takes several hours of operation to achieve a stable minimum condition. The germicidal action appears to be much more rapid than that of ultraviolet light as ordinarily placed in a room but not so fast as with the use of a chemical material such as propylene glycol vapor.