Our main finding was that, among people with asthma, mold odor at home, at work, or both was related to a significantly reduced FEV1 level, which was on average 240 mL lower in those exposed compared with those with no exposure (Table 1). For FVC, we detected a similar, but statistically nonsignificant association. An association was detected mostly in men whose FEV1 was on average 480 mL lower in relation to mold odor. Among women, the corresponding reduction in FEV1 was smaller at 90 mL. Among men also, a dose-response pattern was seen. The other dampness-related exposure did not show consistent associations with lung function.