Using a semi-quantitative mold exposure index, the National Institute for Occupational Safety and Health (NIOSH) investigated 13 college buildings to examine whether building-related respiratory symptoms among employees are associated with environmental exposure to mold and dampness in buildings. We collected data on upper and lower respiratory symptoms and their building-relatedness, and time spent in specific rooms with a self-administered questionnaires. Trained NIOSH industrial hygienists classified rooms for water stains, visible mold, mold odor, and moisture using semi-quantitative scales and then estimated individual exposure indices weighted by the time spent in specific rooms. The semi-quantitative exposure indices significantly predicted building-related respiratory symptoms, including wheeze [odds ratio (OR) = 2.3; 95% confidence interval (CI) = 1.14.5], chest tightness (OR = 2.2; 95% CI = 1.14.6), shortness of breath (OR = 2.7; 95% CI = 1.26.1), nasal (OR = 2.5; 95% CI = 1.34.7) and sinus (OR = 2.2; 95% CI = 1.24.1) symptoms, with exposureresponse relationships. We found that conditions suggestive of indoor mold exposure at work were associated with building-related respiratory symptoms. Our findings suggest that observational semi-quantitative indices of exposure to dampness and mold can support action to prevent building-related respiratory diseases.