Low level ozone exposure at rest causes changes in lung function among healthy volunteers

Ozone (O3) is the most common environmental trigger for asthma attacks, even at concentrations below the EPA 8-hour exposure standard of 0.07 parts per million (ppm). O3 provokes a relatively rapid decrease in Forced Vital Capacity (FVC) and Forced Expiratory Volume in 1 second (FEV1). The O3 dose depends on the concentration and duration of O3 exposure, and exercise intensity. We investigated if exposure to ambient-air O3 concentrations without exercise could still cause changes in lung function. Fourteen healthy, non-smoking volunteers participated in a randomized, double-blinded crossover study. They were exposed to either filtered clean air (FA) or to an average O3 concentration of 0.07 ppm while sedentary. Participants underwent spirometry before and after exposure sessions. The effect of O3 versus FA in %predicted FEV1 and FVC were compared by paired T-tests. Mean and SEM are presented. The mean age of participants was 32 years; half were female. For change in %predicted FEV1, we found a decrease of 2.8 +/- 1.0 points with O3 compared to FA (p=0.02). Although we found a significant reduction in post-O3 to post-FA %predicted FVC of 1.5 +/- 0.5 points (p=0.007), the change from baseline %predicted FVC (1.5 +/- 0.9 points lower with O3) failed to reach significance when comparing O3 to FA (p=0.1). Healthy adults experienced significant drops in lung function after a low-level O3 exposure while sedentary. This data supports epidemiologic evidence whereby exposure to low ambient-air O3 levels produce adverse health effects, especially among susceptible groups including children with asthma.