ACUTE RESPIRATORY HEALTH EFFECTS OF AIR POLLUTION ON ASTHMATIC CHILDREN IN US INNER CITIES

Abstract

ISEE-57 Introduction: Asthmatic children living in inner-city communities are a particularly vulnerable subgroup, both because of their underlying airways disease and their exposure to relatively high levels of motor vehicle emissions. Objective: To investigate the association between short-term fluctuations in outdoor air pollution concentrations and pulmonary function and respiratory symptoms among inner-city asthmatic children. Methods: Between August 1998 and July 2001, 937 moderate-to-severe asthmatic children (age 5–12 years) living in seven US urban communities performed two-week epochs of twice-daily home pulmonary function testing every six months for two years. Every two months, the parent completed a standardized telephone interview about asthma symptoms. Daily measurements of the concentration of PM2.5, O3, NO2, SO2, and CO during the period of health data collection were obtained from the EPA’s Aerometric Information Retrieval System database. The relationship of lung function and symptoms to fluctuations in air pollutant concentrations were analyzed by time-series analysis using mixed effects models. Results: Almost all air pollutant concentrations measured in the study communities were below the National Ambient Air Quality Standards. In single-pollutant models, all five pollutants examined were associated with reduced FEV1 and increased frequency of missing school due to asthma. The concentrations of SO2, NO2, and CO were also associated with increased asthma symptoms. In three-pollutant models including O3, PM2.5, and CO as a surrogate for motor vehicle emissions, all three pollutants were independently associated with reduced lung function, and O3 and CO were associated with increased symptoms. In these models, increases in O3 and CO were independently associated with missing one or more school days due to asthma per 2 weeks (for 20 ppb increase in O3: OR = 1.88, 95% CI 1.47–2.42; for 1.0 ppm increase in CO: OR = 1.76, 95% CI 1.25–2.48). Conclusion: Among inner-city asthmatic children, short-term increases in air pollutant concentrations were associated with adverse health outcomes including reduced pulmonary function, respiratory symptoms, and missed school days related to asthma. Although the observed associations cannot be attributed with certainty to individual pollutants, the associations with CO, likely acting as a surrogate for other pollutants, suggests that one or more components of motor vehicle emissions may be causing excess morbidity among this vulnerable population.