Association Between Outdoor Air Pollution and Childhood Asthma Symptoms in Metropolitan Areas, United States

Abstract

P-079 Introduction: Poor asthma outcomes have been linked to air pollution exposure in many studies focusing on local areas and/or short exposure duration. To assess the association between chronic outdoor air pollution exposure and asthma symptoms among children in metropolitan areas in the United States, air monitoring data from the U.S. Environmental Protection Agency (EPA) were merged with data from the National Health Interview Survey (NHIS). Methods: Annual average air pollutant levels for five criteria pollutants (particulate matter, ozone, sulfur dioxide, nitrogen dioxide, and carbon monoxide) were compiled by county for 2000–2003. The sample children in the study were ages 3–17 years residing in U.S. metropolitan areas for whom health conditions were reported in the 2001–2004 NHIS. Data for sample children were matched with exposure data for the previous 12 months when available for the county where they resided at the time of the NHIS interview. County-level pollutant values were ranked into quartiles. Logistic regression using survey sample weights was used to assess association between asthma outcomes (current asthma, recent asthma attack, and recent emergency room visit for asthma) and monitored air pollutant levels. Results: After adjusting for race/ethnicity, sex, parental education, poverty status, central city residence, and single parent household, the authors found that children living in the counties in the highest quartiles for all pollutants except carbon monoxide were generally more likely to have current asthma, a reported asthma attack in the previous 12 months, and a reported asthma emergency room visit in the previous 12 months than those residing in counties with pollution values ranked in the lower quartiles. For example, for children living in the highest quartile of pollution levels for particulate matter (aerodynamic diameter less than or equal to 2.5 micrometers), the adjusted odds ratio for current asthma was 1.53 (95% confidence interval [CI]: 1.06–2.23), for recent asthma attack 1.38 (95% CI: 0.95–2.01), and for asthma emergency room visit 1.73 (95% CI: 1.01–2.97). Conclusion: This analysis suggests that chronic exposure to air pollution in metropolitan areas throughout the U.S. may be associated with increased current asthma rates and ongoing asthma symptoms among children.