The relation between fungal propagules in indoor air and home characteristics

Background: Questionnaires are commonly used in epidemiologic studies to ob tain information about house characteristics in order to predict the househ old aeroallergen exposure levels. However, the reliability of the predictio ns made with the questionnaires has not been evaluated. To address this iss ue, we compared objectively measured fungal propagules including the most f requently 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 resi dential 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 p ortable air sampler was used in combination with DG-18 and MEA agars. A que stionnaire was used to obtain information on host and house characteristics that may have an impact on the presence of fungal propagules in the air. T his included information on observation of moisture problems (e.g., water l eakage or damage, and mold or mildew growth), ventilation and heating facil ities, building age and type, number of occupants, annual household income, presence of pets and pests, cleaning regimens, etc. Results: The number of CFU/m(3) air collected on MEA was significantly high er than on DG-18 (means, respectively, 1033.5 and 846.0 CFU/m(3)) (P < 0.00 05). However, there was no significant difference between the numbers of CF U/m(3) 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 in door air. Only the temperature, relative humidity, season, and cats inside homes had a statistically significant impact on the presence of fungal prop agules in indoor air. Conclusions: The presence of fungal propagules in indoor air cannot be reli ably predicted by home characteristics. Actual measurements are required fo r fungal exposure assessment, and the use of only;one medium to collect sam ples in one location in a home might be adequate to represent residential l evels of fungi in indoor air.