Research

Air pollution attributable postneonatal infant mortality in U.S. metropolitan areas: a risk assessment study

Reinhard Kaiser¹ , Isabelle Romieu² , Sylvia Medina³ , Joel Schwartz⁴ , Michal Krzyzanowski⁵ and Nino Künzli^1,6

¹Institute for Social and Preventive Medicine, University of Basel, Steinengraben 49, 4051 Basel, Switzerland

²Instituto Nacional de Salud Publica, Av.Universidad 655, Planta Baja, Col. Santa María Ahuacatitlán, 62508 Cuernavaca, Morelos, México

³Air pollution program, Department of Environmental Health, National Institute of Public Health Surveillance (InVS), 12 rue du Val d'Osne 94415 Saint Maurice cedex, France

⁴Exposure, Epidemiology and Risk Program, Department of Environmental Health, Harvard School of Public Health, Landmark Center, West 401 Park Drive, Boston MA 02215 USA

⁵World Health Organization, European Centre for Environment and Health, Bonn Office, Goerresstrasse 15, 53113 Bonn, Germany

⁶Division of Environmental Health, Department of Preventive Medicine, Keck School of Medicine University of Southern California, 1540 Alcazar Street, CHP 236, Los Angeles, CA 90033 USA

author email corresponding author email

Environmental Health: A Global Access Science Source 2004, 3:4doi:10.1186/1476-069X-3-4

Published:	5 May 2004

Abstract

Background

The impact of outdoor air pollution on infant mortality has not been quantified.

Methods

Based on exposure-response functions from a U.S. cohort study, we assessed the attributable risk of postneonatal infant mortality in 23 U.S. metropolitan areas related to particulate matter <10 μm in diameter (PM₁₀) as a surrogate of total air pollution.

Results

The estimated proportion of all cause mortality, sudden infant death syndrome (normal birth weight infants only) and respiratory disease mortality (normal birth weight) attributable to PM₁₀ above a chosen reference value of 12.0 μg/m³ PM₁₀ was 6% (95% confidence interval 3–11%), 16% (95% confidence interval 9–23%) and 24% (95% confidence interval 7–44%), respectively. The expected number of infant deaths per year in the selected areas was 106 (95% confidence interval 53–185), 79 (95% confidence interval 46–111) and 15 (95% confidence interval 5–27), respectively. Approximately 75% of cases were from areas where the current levels are at or below the new U.S. PM_2.5 standard of 15 μg/m³ (equivalent to 25 μg/m³ PM₁₀). In a country where infant mortality rates and air pollution levels are relatively low, ambient air pollution as measured by particulate matter contributes to a substantial fraction of infant death, especially for those due to sudden infant death syndrome and respiratory disease. Even if all counties would comply to the new PM_2.5 standard, the majority of the estimated burden would remain.

Conclusion

Given the inherent limitations of risk assessments, further studies are needed to support and quantify the relationship between infant mortality and air pollution.