Outdoor Ozone and Building Related Symptoms in the BASE Study

Reactions between ozone and indoor contaminants can influence human health and indoor air quality. The U.S. EPA Building Assessment Survey and Evaluation (BASE) study data were analyzed for associations between outdoor ozone concentrations and building related symptom (BRS) prevalence. Multiple logistic regression (MLR) models, adjusted for personal, workplace and environmental variables, revealed positive relationships (p<0.05) between ozone concentrations and upper respiratory (UR), dry eyes, neurological and headache BRS (odds ratios ranged from 1.03-1.04 per 10 μg m 3 increase in outdoor ozone concentrations). Other BRS had marginally significant relationships with ozone (p<0.10). A linear dose-response in UR symptoms was observed with increasing outdoor ozone (p=0.03); most other symptoms showed similar but not statistically significant trends. Outdoor ozone correlated with indoor concentrations of several aldehydes, a pattern suggesting that indoor ozone chemistry was occurring. Coupled with the MLR ozone-BRS analysis, this correlation supports the hypothesis that ozone-initiated indoor reactions play an important role in the indoor air quality and building occupant health. Replication with increased statistical power and with longitudinal data is needed. If the observed associations are confirmed as causal, ventilation system ozone removal technologies could improve building occupant health when higher ambient ozone levels are present.