Indoor mold odor in the workplace increases the risk of Asthma-COPD Overlap Syndrome: a population-based incident case-control study

Background Previous studies have suggested an increased risk of asthma related to indoor dampness problems, but their role in the etiology of Asthma-COPD Overlap Syndrome has not been studied. We utilized a population-based incident case-control study to assess potential effect of indoor dampness and molds at home and at work on development of ACOS. Methods We recruited systematically all new cases of asthma diagnosed during a 2.5-year study period (1997-2000) and randomly selected controls from the source population of adults 21-63 years old and representing 500,000 persons-years in the Pirkanmaa Hospital District, South Finland. Exposure indicators included water damage, damp stains or paint peeling, visible mold, and mold odor, asked separately for home and workplace. The clinically diagnosed case series consisted of 521 adults with newly diagnosed asthma. Altogether 25 of them satisfied the criteria for ACOS-cases, i.e. FEV1/FVC < 0.70 in post-bronchodilator spirometry. The control series, including 932 controls, were from a random sample of source population, after excluding 76 (7.5%) controls with asthma. Results In logistic regression analysis adjusting for confounders, the risk of ACOS was significantly related to presence of mold odor in the workplace (OR 3.43; 95% CI 1.04-11.29), but not to other dampness indicators. The fraction of ACOS attributable to workplace mold odor was 70.8% (95% CI 3.8-91.1%) among the exposed. The risk of ACOS was not related to mold exposures at home. Conclusions Present results provide new evidence of the significant relation between workplace exposure to mold odor and adult-onset ACOS.