Mould and dampness in dwelling places, and onset of asthma: the population-based cohort ECRHS.

OBJECTIVES To study new onset of adult asthma in relation to dampness and moulds in dwelling places. METHODS Totally, 7104 young adults from 13 countries who participated in the European Community Respiratory Health Survey (ECRHS I and II) who did not report respiratory symptoms or asthma at baseline were followed prospectively for 9 years. Asthma was assessed by questionnaire data on asthmatic symptoms and a positive metacholine challenge test at follow-up. Data on the current dwelling was collected at the beginning and at the end of the follow-up period by means of an interviewer-led questionnaire, and by inspection. Relative risks (RR) for new onset asthma were calculated with log-binomial models adjusted for age, sex, smoking and study centre. RESULTS There was an excess of new asthma in subjects in homes with reports on water damage (RR 1.46; 95% CI 1.09 to 1.94) and indoor moulds (RR=1.30; 95% CI 1.00 to 1.68) at baseline. A dose-response effect was observed. The effect was stronger in those with multisensitisation and in those sensitised to moulds. Observed damp spots were related to new asthma (RR=1.49; 95% CI 1.00 to 2.22). The population-attributable risk was 3-10% for reported, and 3-14% for observed dampness/moulds. CONCLUSIONS Dampness and mould are common in dwellings, and contribute to asthma incidence in adults.