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The Effects of Outdoor Air Pollutants on the Costs of Pediatric Asthma Hospitalizations in the United States, 1999 to 2007

Roy, Angkana MD, MPH; Sheffield, Perry MD, MPH; Wong, Kendrew; Trasande, Leonardo MD, MPP

doi: 10.1097/MLR.0b013e31820fbd9b
Original Articles

Background Acute exposure to outdoor air pollutants has been associated with increased pediatric asthma morbidity. However, the impact of subchronic exposures is largely unknown.

Objective To examine the association between subchronic exposure to 6 outdoor air pollutants (PM2.5, PM10, ozone, nitrogen oxides, sulfur oxides, carbon monoxide) and pediatric asthma hospitalization length of stay, charges, and costs.

Methods We linked pediatric asthma hospitalization discharge data from a nationally representative dataset, the 1999-2007 Nationwide Inpatient Sample, with outdoor air pollution data from the Environmental Protection Agency. Hospitals with no air quality data within 10 miles were excluded. Our predictor was the average concentration of 6 pollutants near the hospital during the month of admission. We conducted bivariate analyses using Spearman correlations and multivariable analyses using Poisson regression for length of stay and linear regression for log-transformed charges and costs, controlling for patient demographics, hospital characteristics, and month of admission.

Results In unadjusted analyses, all 6 pollutants had minimal correlation with the 3 outcomes (ρ<0.1, P<0.001). In multivariable analyses, a 1-unit (μg/m3) increase in monthly PM2.5 led to a $123 increase in charges (95% confidence interval $40-249) and a $47 increase in costs (95% confidence interval $15-93). No other pollutants were significant predictors of charges or costs or length of stay.

Conclusion Subchronic PM2.5 exposure is associated with increased costs for pediatric asthma hospitalizations. Policy changes to reduce outdoor subchronic pollutant exposure may lead to improved asthma outcomes and substantial savings in healthcare spending.

Departments of Preventive Medicine and Pediatrics, Mount Sinai School of Medicine, NY

Supported by the National Institutes of Health Research Training Grant in Environmental Pediatrics (NIH 5T32 HD049311) and the Mount Sinai Children's Environmental Health Center.

The authors declare no conflict of interest.

Reprints: Angkana Roy, MD, MPH, 1701 W Superior St, Chicago, IL 60622. e-mail:

Copyright © 2011 Wolters Kluwer Health, Inc. All rights reserved.