THE EFFECTS OF AMBIENT OZONE ON LUNG-FUNCTION IN CHILDREN - A REANALYSIS OF 6 SUMMER CAMP STUDIES

Studies of children attending summer camps often have observed relatio nships between daily outdoor ozone (O-3) concentrations and decreased lung function that are qualitatively similar to results seen in human chamber studies. The former studies, focusing on the pulmonary effects of O-3 and associated pollutants on children under natural conditions of exposure, are potentially of great importance to understanding the public health impact of ambient O-3. However, a thorough assessment o f the results of these studies has been hampered by differences in the analysis and reporting of data across the various studies. We obtaine d data sets from six summer camp studies carried out by three separate investigative groups, including two New Jersey studies performed by N ew York University, two studies in Ontario carried out by Health and W elfare Canada, and two studies in southern California. The data consis ted of sequential, daily measurements of forced expiratory volume in 1 sec (FEV(1)), peak expiratory flow rare (PEFR), and 1-hr O-3 concentr ation in the hour preceding lung function measurements for each child. We analyzed the relationships between lung function and O-3 using lin ear regression models that fit subject-specific intercepts and a singl e, pooled O-3 slope, These models were fit for each of the six studies separately and for all studies combined. All of the study-specific sl opes of FEV(1) on O-3 were negative (i.e., increased O-3 associated wi th decreased FEV(1)); five of six were statistically significant. Anal ysis of the combined six-study data set yielded a slope of -0.50 mi FE V(1)/ppb O-3 (p<0.0001). Addition of time-trend variables to the combi ned-data analysis diminished, but did not eliminate, the FEV(1)-O-3 re lationship. Study-specific slopes for PEFR on O-3 were more variable. Combined over studies, no significant relationship was observed betwee n PEFR and O-3. However, this negative finding appeared to be partiall y confounded by time trends in PEFR. The results of this reanalysis pr ovide strong evidence that children exposed to O-3 under natural condi tions experience decreases in FEV(1) of the kind demonstrated in labor atory studies, and raise concern that other acute respiratory effects observed in those studies (e.g., pulmonary inflammation) may also occu r in young people exposed to ambient O-3.