The relation between fungal propagules in indoor air and home characteristics.

BACKGROUND: Questionnaires are commonly used in epidemiologic studies to obtain information about house characteristics in order to predict the household aeroallergen exposure levels. However, the reliability of the predictions made with the questionnaires has not been evaluated. To address this issue, we compared objectively measured fungal propagules including the most frequently isolated mold genera (i.e., Alternaria, Aspergillus, Cladosporium, Penicillium, etc.) in a large sample of homes and compared these measured values to the questionnaire-determined household characteristics. METHODS: As part of a prospective cohort study on the relation between residential allergen exposure and development of asthma in neonates, fungal air samples were collected from infant bedrooms and main living areas in 1000 homes in the Northeast USA, from December 1996 to January 1999. A Burkard portable air sampler was used in combination with DG-18 and MEA agars. A questionnaire was used to obtain information on host and house characteristics that may have an impact on the presence of fungal propagules in the air. This included information on observation of moisture problems (e.g., water leakage or damage, and mold or mildew growth), ventilation and heating facilities, building age and type, number of occupants, annual household income, presence of pets and pests, cleaning regimens, etc. RESULTS: The number of CFU/m3 air collected on MEA was significantly higher than on DG-18 (means, respectively, 1033.5 and 846.0 CFU/m3) (P < 0.0005). However, there was no significant difference between the numbers of CFU/m3 air collected from the main living area and from the infant bedroom. There was only a very weak relationship between the house characteristics, as described by questionnaire, and the presence of fungal propagules in indoor air. Only the temperature, relative humidity, season, and cats inside homes had a statistically significant impact on the presence of fungal propagules in indoor air. CONCLUSION: The presence of fungal propagules in indoor air cannot be reliably predicted by home characteristics. Actual measurements are required for fungal exposure assessment, and the use of only one medium to collect samples in one location in a home might be adequate to represent residential levels of fungi in indoor air.

Comparisons of seasonal fungal prevalence in indoor and outdoor air and in house dusts of dwellings in one Northeast American county.

Fungi cause allergies and many other adverse health effects. In this study, we characterized the nature and seasonal variation of fungi inside and outside homes in the Greater New Haven, Connecticut area. Three indoor air samples (in the living room, bedroom, and basement) and one outdoor sample were collected by the Burkard portable air sampler. House dust samples were collected in the living room by a vacuum cleaner. The mold concentrations varied widely from house to house in both indoor and outdoor air. No significant difference (p>0.05) in concentration and type of fungi between living room and bedroom or by season was observed. Both concentration and type of fungi were significantly higher (p<0.05) in the basement than other indoor areas and outdoor air in winter. The type of fungi in living room, bedroom, and outdoor air were found to have significant changes among seasons, but there was no significant difference for the basement among seasons. Cladosporium spp. was dominant in both indoor and outdoor air in summer. Penicillium and Aspergillus were dominant in indoor air in winter, but neither was dominant in any season in outdoor air. The type of fungi and their concentrations in house dust samples were not representative of those isolated in indoor air. In dust samples, more Mucor, Wallemia, and Alternaria species, but less Aspergillus, Cladosporium, and Penicillium species were found in all seasons. Air sampling in spring or fall in every suspected house is suggested for year-round fungal exposure assessment.