AIR-POLLUTION AND CHILDHOOD RESPIRATORY HEALTH - EXPOSURE TO SULFATE AND OZONE IN 10 CANADIAN RURAL COMMUNITIES

This study was designed to examine differences in the respiratory heal th status of preadolescent school children, aged 7-11 years, who resid ed in 10 rural Canadian communities in areas of moderate and low expos ure to regional sulfate and ozone pollution. Five of the communities w ere located in central Saskatchewan, a low-exposure region, and five w ere located in southwestern Ontario, an area with moderately elevated exposures resulting from long-range atmospheric transport of polluted air masses. In this cross-sectional study, the child's respiratory sym ptoms and illness history were evaluated using a parent-completed ques tionnaire, administered in September 1985. Respiratory function was as sessed once for each child in the schools between October 1985 and Mar ch 1986, by the measurement of pulmonary function for forced vital cap acity (FVC), forced expiratory volume in 1 sec (FEV(1.0)), peak expira tory flow rate (PEFR), mean forced expiratory flow rate during the mid dle half of the FVC curve (FEF(25-75)), and maximal expiratory flow at 50% of the expired vital capacity (V(50)max). The 1986 annual mean of the l-hr daily maxima of ozone was higher in Ontario (46.3 ppb) than in Saskatchewan (34.1 ppb), with 90th percentile concentrations of 80 ppb in Ontario and 47 ppb in Saskatchewan. Summertime 1-hr daily maxim a means were 69.0 ppb in Ontario and 36.1 ppb in Saskatchewan. Annual mean and 90th percentile concentrations of inhalable sulfates were thr ee times higher in Ontario than in Saskatchewan; there were no signifi cant differences in levels of inhalable particles (PM(10)) or particul ate nitrates. Levels of sulfur dioxide (SO2) and nitrogen dioxide (NO2 ) were low in both regions. After controlling for the effects of age, sex, parental smoking, parental education, and gas cooking, no signifi cant regional differences were observed in rates of chronic cough or p hlegm, persistent wheeze, current asthma, bronchitis in the past year, or any chest illness that kept the child at home for 3 or more consec utive days during the previous year. Children living in southwestern O ntario had statistically significant (P < 0.01) mean dec rements of 1. 7% in FVC and 1.3% in FEV(1.0) compared with Saskatchewan children, af ter adjusting for age, sex, weight, standing height, parental smoking, and gas cooking. There were no statistically significant regional dif ferences in the pulmonary flow parameters (P, 0.05). (C) 1994 Academic Press, Inc.