Air pollution attributable postneonatal infant mortality in U.S. metropolitan areas: a risk assessment study.
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 microm 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 microg/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. PM2.5 standard of 15 microg/m3 (equivalent to 25 microg/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 PM2.5 standard, the majority of the estimated burden would remain.


CONCLUSIONS
Given the inherent limitations of risk assessments, further studies are needed to support and quantify the relationship between infant mortality and air pollution.
Kaiser
Reinhard
R
Institute for Social and Preventive Medicine, University of Basel, Steinengraben 49, 4051 Basel, Switzerland. RKaiser@cdc.gov
Romieu
Isabelle
I
Medina
Sylvia
S
Schwartz
Joel
J
Krzyzanowski
Michal
M
Künzli
Nino
N
D000393:Air Pollutants / Q000032:analysis* / Q000633:toxicity; D000397:Air Pollution / Q000009:adverse effects / Q000032:analysis* / Q000706:statistics & numerical data; D001724:Birth Weight; D002423:Cause of Death; D015331:Cohort Studies; D016001:Confidence Intervals; D004781:Environmental Exposure / Q000009:adverse effects / Q000032:analysis*; D006801:Humans; D007226:Infant Mortality; D007231:Infant, Newborn; D012140:Respiratory Tract Diseases / Q000401:mortality; D018570:Risk Assessment; D013398:Sudden Infant Death / Q000453:epidemiology; D014481:United States / Q000453:epidemiology; D014504:Urban Health / Q000706:statistics & numerical data*
D000393:Air Pollutants