Indoor air quality and health: validity and determinants of reported home dampness and moulds.

Background. Questionnaire-based surveys from several countries have consistently detected adverse health associated with home dampness and mould growth. Methods. To test the validity of questions commonly used to indicate the presence of indoor mould, questionnaires were administered in 403 homes where dust samples were taken for viable fungi and air samples for ergosterol. Results. Geometric mean concentrations of the total viable fungi were 255 (SE 116) x 10 3 CFU/g when mouldy odours were reported and 155 (SE 55) when odours were not reported (P 0.01). Similarly, reported water damage was associated with a 50% increase (P= 0.06). Geometric mean concentrations of the predominantly indoor-source fungi, Aspergillus plus Penicillium, were twice as high when mould or mildew was reported than when not mentioned (P=0.01). The presence of reported mould or water damage was unrelated to the presence of detectable levels of ergosterol. There was evidence for reporting bias: in the presence of low concentrations of viable fungi in dust, respondents reporting allergies were more likely to report visible mould growth (odds ratio [OR] =1.8, 95% confidence interval [Cl] : 0.9-3.5, P= 0.10. In the presence of elevated concentrations of dust fungi, respondents who smoked were less likely to report visible mould growth, (OR = 0.4, 95% Cl : 0.2-0.7, P = 0.005). Conclusions. Reported mould, water damage, and mouldy odours were associated with elevated levels of indoor fungi. However, inaccuracy was high and there was evidence of a systematic reporting bias. Future research should concentrate on developing accurate objective measures of exposure to fungi, and then use this information to develop valid questionnaires. Currently, objective measures, not questionnaires, are recommended to clarify the health effects of indoor fungi.