Purpose: Epidemiological evidence shows that indoor dampness is associated with respiratory symptoms, the aggravation of preexisting asthma, and the development of new-onset asthma. Follow-up studies indicate that symptoms compatible with asthma constitute risk factors for the future development of asthma. The aims of the study were (1) to assess whether asthma-like symptoms (cough, dyspnea, and wheeze) that occur in relation to exposure to damp and moldy work environments lead to the later development of asthma and (2) to assess the importance of continued exposure to indoor dampness and molds at work in the development of asthma.
Methods: We followed 483 patients with asthma-like symptoms related to damp workplaces but without objective evidence of asthma in baseline examinations. The development of asthma and present work conditions were established with the use of a questionnaire 3-12 years later.
Results: A total of 62 patients (13%) reported having developed asthma during the study period. Continued exposure to a damp or moldy environment was associated with a more than fourfold increase in the risk of asthma (odds ratio 4.6, 95% confidence interval 1.8-11.6). Working in a non-remediated environment at follow-up was the strongest risk factor for developing asthma. The remediation of damp buildings seemed to be associated with a decrease in the risk of asthma.
Conclusions: The results indicate that exposure at work to dampness and molds is associated with the occurrence of new-onset asthma. Exposed workers suffering from asthma-like symptoms represent a risk group for the development of asthma. The risk appears especially high if the exposure continues. Due to inherent weaknesses of patient series, the findings need corroborative studies.