Chronic Exposure to Ambient Ozone and Lung Function in Young Adults

BACKGROUND: Tropospheric ozone (O3) is an oxidant, outdoor air pollutant. Chronic exposure has been associated with decreased lung function in children and adolescents. This study investigated the effects of long-term exposure to O3 on lung function in college freshmen. METHODS: We recruited University of California, Berkeley students (n=255) who were lifelong residents of the Los Angeles and San Francisco Bay areas and who never smoked. Lifetime exposures to O3, small particulate matter (PM10), and nitrogen dioxide (NO2) were based on spatial interpolation of compliance monitor measurements to all residences at which students lived. Spirometry was performed between February and May, times when students would not have had recent exposure to increased levels of O3. RESULTS: Lifetime exposure to O3 was associated with decreased levels of measures of small airways (<2 mm) function (FEF75 and FEF25-75). There was an interaction with the FEF25-75/FVC ratio, a measure of intrinsic airway size. Subjects with a large ratio were less likely to have decreases in FEF75 and FEF25-75 for a given estimated lifetime exposure to O3. This association was not altered by history of chronic respiratory disease, allergy, second-hand exposure to environmental tobacco smoke, exposure to PM10 and NO2, or measurement errors in exposure assessment. CONCLUSIONS: A history of increased level of lifetime exposure to ambient O3 is associated with decreased function of airways in which O3 deposition in the lungs is the greatest. Adolescents with intrinsically smaller airways appear to be at greatest risk. Any environmental or genetic factors that lead to reduced airway size may lead to increased susceptibility to the adverse effects of ambient ozone.