Mould and dampness in the 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.