Air pollution and infant death in southern California, 1989-2000.
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 microm 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-microg/m3 increase in particulate matter < 10 microm 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.
Ritz
Beate
B
Department of Epidemiology, School of Public Health, University of California, Los Angeles, PO Box 951772, 650 Charles E. Young Dr, Los Angeles, California 90095-1772, USA. britz@ucla.edu
Wilhelm
Michelle
M
Zhao
Yingxu
Y
D000388:Air / Q000032:analysis; D000393:Air Pollutants / Q000032:analysis*; D000397:Air Pollution / Q000009:adverse effects*; D002140:California / Q000453:epidemiology; D002248:Carbon Monoxide / Q000032:analysis; D016022:Case-Control Studies; D003644:Death Certificates; D004784:Environmental Monitoring; D062665:Epidemiological Monitoring; D005260:Female; D006801:Humans; D007223:Infant; D007226:Infant Mortality; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D007234:Infant, Premature; D007235:Infant, Premature, Diseases / Q000209:etiology / Q000401:mortality; D008297:Male; D009585:Nitrogen Dioxide / Q000032:analysis; D010126:Ozone / Q000032:analysis; D010316:Particle Size; D012120:Respiration Disorders / Q000209:etiology / Q000401:mortality; D018570:Risk Assessment; D012307:Risk Factors; D013398:Sudden Infant Death / Q000453:epidemiology / Q000209:etiology
D000393:Air Pollutants; D010126:Ozone; D002248:Carbon Monoxide; D009585:Nitrogen Dioxide