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

The study compared the atmospheric burden of viable particulates in the interiors of condominium homes with central air conditioning with that of the typically more open type of naturally ventilated Hawaiian residence. Enumeration of the numbers and types of respirable fungi and bacteria inside were done using Andersen microbial air samplers. To evaluate the impact of the air conditioning system on indoor air quality the results were compared with those obtained outside the homes. No significant differences were found in microbial air contaminants between the outdoors and the inside air of naturally ventilated homes. In air conditioned homes the air were found to have fewer fungi, including a significantly smaller number of Cladosporiem sp., but had a significantly greater number of Aspergillus sp. compared to outside air. The total number of bacteria and Gram positive cocci was significantly greater inside air conditioned residences than outside. A survey of health status showed that occupants of centrally air conditioned homes had more complaints of eye irritation, sneezing, nasal congestion and coughs.