[Airborne concentrations of fungal and indoor air pollutants in dwellings in Nagoya, Japan].

PURPOSE

The purpose of this study was to determine airborne fungal concentrations in dwellings and to evaluate the relationship between indoor air concentrations of fungi and those of indoor air pollutants, temperature and relative humidity.

METHODS

Indoor and outdoor concentrations of total fungi, xerophiles (xerophilic fungi), indoor air pollutants such as formaldehyde, nitrogen dioxide, carbon dioxide, carbon monoxide, temperature and relative humidity were measured in 54 dwellings in Nagoya, Japan. This study was performed in summer and winter from 1995 to 1998. The airborne fungal concentrations were analyzed using a pinhole air sampler and dichloran 18% glycerol agar (DG18), and compared with the levels assessed with potato dextrose agar (PDA).

RESULTS

1. DG18 can be recommended as an excellent medium for determining viable fungi concentrations in indoor air. 2. In indoor air, geometric means of total fungal and xerophile concentrations in summer were 237-301 CFU/m3 and 24.1-26.8 CFU/m3, as compared to 78.7-87.5 CFU/m3 and 18.2-29.5 CFU/m3, respectively, in winter. In outdoor air, geometric means of total fungal and xerophile concentrations in summer were 208 CFU/m3 and 9.2 CFU/m3, and 72.7 CFU/m3 and 10.1 CFU/m3, respectively, in winter. 3. The predominant genera in indoor and outdoor air were Cladosporium spp., followed by Penicillium spp. and Aspergillus spp. The major Aspergillus spp. was A. restrictus. 4. Indoor as well as outdoor air concentrations of total fungi were significantly higher in summer than in winter (P < 0.01), whereas differences in total fungal concentrations between indoor and outdoor air were not. Airborne xerophile concentrations in summer and winter were significantly higher in indoor air than in outdoor air (P < 0.01), while indoor as well as outdoor air xerophile concentrations in summer were similar to those in winter. 5. The total fungal and xerophile concentrations were not dependent on dwelling factors such as the type of dwellings, the type of flooring materials and the use of air-conditioners and/or heaters. 6. The total fungal and xerophile concentrations were not significantly correlated with the concentrations of all the indoor air pollutants. In winter, the total fungal and xerophile concentrations significantly increased in proportion to the average relative humidity (P < 0.01).

CONCLUSION

The total fungal concentrations in indoor air were significantly correlated with those in outdoor air, while xerophile concentrations were not. The indoor air concentrations of total fungi and xerophiles were not dependent on those of indoor air pollutants.