The Harvard Southern California chronic ozone exposure study: Assessing ozone exposure of grade-school-age children in two Southern California communities

The Harvard Southern California Chronic Ozone Exposure Study measured perso nal exposure to, and indoor and outdoor ozone concentrations of, approximat ely 200 elementary school children 6-12 years of age for 12 months (June 19 95-May 1996). We selected two Southern California communities, Upland and s everal towns located in the San Bernardino mountains, because certain chara cteristics of chose communities were believed to affect personal exposures. On 6 consecutive days during each study month, participant homes were moni tored for indoor and outdoor ozone concentrations, and participating childr en wore a small passive ozone sampler to measure personal exposure. During each sampling period, the children recorded time-location-activity informat ion in a diary. Ambient ozone concentration data were obtained from air qua lity monitoring stations in the study areas. We present ozone concentration data for the ozone season (June-September 1995 and May 1996) and the nonoz one season (October 1995-April 1996). During the ozone season, outdoor and indoor concentrations and personal exposure averaged 48.2, 11.8, and 18.8 p pb in Upland and 60.1, 21.4, and 25.4 ppb in the mountain towns, respective ly. During the nonozone season, outdoor and indoor concentrations and perso nal exposure averaged 21.1, 3.2, and 6.2 ppb in Upland, and 35.7, 2.8, and 5.7 ppb in the mountain towns, respectively. Personal exposure differed by community and sex, but not by age group.