Airborne microbial contaminants in indoor environments. Naturally ventilated and air-conditioned homes

The atmospheric burden of viable particulates in the interiors of condominium homes with central air conditioning was compared with that of the typically more open-type of naturally ventilated Hawaiian homes. Andersen microbial air samplers were used to enumerate the numbers and kinds of respirable fungi and bacteria inside the residences. The results were compared with that obtained outside the homes to evaluate the impact of the air conditioning systems on indoor air quality. There were no significant differences in microbial air contaminants between the outdoors and the air inside naturally ventilated residences. The air inside air conditioned homes were found to have fewer fungi, including a significantly smaller number of Cladosporium sp., but had a significantly greater number of Aspergillus sp. when compared to the outdoors. The total number of bacteria and the number of Gram positive (+) cocci were significantly larger inside air-conditioned residences than outside. A preliminary health status survey revealed occupants of centrally air-conditioned homes had more complaints of eye irritation, sneezing, nasal congestion, and cough.