Abstract
The number of microorganisms in humidified water was counted and the transmission of microorganisms from humidified water into air was investigated from the hygienic standpoint of humidification in an air conditioning system. The following results were obtained. 1) The recirculating city water and hot water for heating coils and heat storage tank used as humidified water contained a high density of many kinds of microorganisms, such as bacteria, mold, and protozoa. 2) Humidification transmits the microorganisms in the humidified water into the supply air by humidifying so that the air in the room is contaminated. 3) The number of microorgamisms transmitted into the air by humidification depends on the increase in the moisture content in the air and the number of microorganisms in the humidified water.
