Outdoor Air Pollution Causes Infant Deaths

http://pediatrics.aappublications.org/cgi/content/abstract/118/2/493?ct=ct


PEDIATRICS Vol. 118 No. 2 August 2006, pp. 493-502 (doi:10.1542/peds.2006-0027)

ARTICLE
Air Pollution and Infant Death in Southern California, 1989–2000 Beate Ritz, MD, PhDa,b, Michelle Wilhelm, PhDa,b and Yingxu Zhao, PhDa
a Department of Epidemiologyb Center for Occupational and Environmental Health, School of Public Health, University of California, Los Angeles, California

OBJECTIVE. We evaluated the influence of outdoor air pollution on infant death in the South Coast Air Basin of California, an area characterized by some of the worst air quality in the United States.

METHODS. Linking birth and death certificates for infants who died between 1989 and 2000, we identified all infant deaths, matched 10 living control subjects to each case subject, and assigned the nearest air monitoring station to each birth address. For all subjects, we calculated average carbon monoxide, nitrogen dioxide, ozone, and particulate matter <10 µm in aerodynamic diameter exposures experienced during the 2-week, 1-month, 2-month, and 6-month periods before a case subject's death.

RESULTS. The risk of respiratory death increased from 20% to 36% per 1-ppm increase in average carbon monoxide levels 2 weeks before death in early infancy (age: 28 days to 3 months). We also estimated 7% to 12% risk increases for respiratory deaths per 10-µg/m3 increase in particulate matter <10 µm in aerodynamic diameter exposure experienced 2 weeks before death for infants 4 to 12 months of age. Risk of respiratory death more than doubled for infants 7 to 12 months of age who were exposed to high average levels of particulates in the previous 6 months. Furthermore, the risk of dying as a result of sudden infant death syndrome increased 15% to 19% per 1-part per hundred million increase in average nitrogen dioxide levels 2 months before death. Low birth weight and preterm infants seemed to be more susceptible to air pollution-related death resulting from these causes; however, we lacked statistical power to confirm this heterogeneity with formal testing.

CONCLUSIONS. Our results add to the growing body of literature implicating air pollution in infant death from respiratory causes and sudden infant death syndrome and provide additional information for future risk assessment.

Key Words: air pollution • infant death • postneonatal death • epidemiology • respiratory death • sudden infant death syndrome • mortality
Abbreviations: PM10—particulate matter <10 µm in aerodynamic diameter • SoCAB—South Coast Air Basin • CI—confidence interval • OR—odds ratio • SIDS—sudden infant death syndrome • ICD-9—International Classification of Diseases, 9th Revision • ICD-10—International Classification of Diseases, 10th Revision • pphm—parts per hundred million • O3—ozone • NO2—nitrogen dioxide • CO—carbon monoxide • LBW—low birth weight • SO2—sulfur dioxide • PM2.5—particulate matter <2.5 µm in aerodynamic diameter