Short-Term and Long-Term Effects of AIr Pollution on Lung Function

ISEE-73 Introduction: We previously reported that annual mean particulate air pollution concentrations were associated with lower lung function in a cross-sectional study of schoolchildren in 24 cities across the United States and Canada. In this analysis we estimated the effects of daily pollution on pulmonary function testing to assess the short-term effects in a sample of more than 10,000 schoolchildren in 22 of the original 24 study sites. Methods: We used a mixed linear model with random city effects to regress the logarithms of pulmonary function parameters (FVC, FEV1.0, FEF25-75%, and PEFR) against sex, age, log height and weight, an interaction of sex and log height, indicators for environmental tobacco smoke exposure and asthma, and air pollution measurements. Long-term exposure was estimated as the annual mean concentrations for the 12 months preceding the pulmonary function tests and short-term exposure as the 6-day moving average of the daily deviations from the long-term annual means. Results: Increased long-term particulate and ozone concentrations were associated with decreased lung function in the range of –1.5% to –3.5%. Increased short-term pollution in PM2.1 and PM10 was associated with decreased FVC, FEV1.0, and FEF25-75%. A 5.8 μg/m3 increase in the 6-day moving average of PM2.1 was associated with a 0.34% lower FVC (95% CI: −0.65, −0.04%), with a 0.35% lower FEV1.0 (−0.68%, −0.02%), and a 0.47% lower FEF25-75% (−1.29, 0.36). Short-term effects of ozone on FVC, FEV1.0, and FEF25-75%, were consistently higher for asthmatic children compared to non-asthmatics, and short-term effects of particles and ozone on FVC and FEV1.0 were consistently higher for obese children compared to non-obese children. There was no indication of effect modification by gender or environmental tobacco smoke exposure. Inclusion of the short-term air pollution effects consistently led to slightly stronger negative effects of the long-term effects. Discussion: This study showed that in addition to the impact of long-term exposure the pulmonary function performance is influenced by air pollution concentrations in the days before the test. These acute effects are smaller than the chronic effects and the effects on lung function for acute and chronic air pollution exposure are independent and additive.