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Reference A Statewide Nested Case-Control Study of Preterm Birth and Air Pollution by Source and Composition: California, 2001-2008.

Authors Laurent O, Hu J, Li L, Kleeman MJ, Bartell SM, Cockburn M, Escobedo L, Wu J.
Institution Program in Public Health, 653 East Peltason Drive, University of California, Irvine, California, USA.
Citation Environ Health Perspect. 2016 Feb 19.
DOI ID 10.1289/ehp.1510133
PubMed® ID 26895492
Review Status Is curated Curated.
Abstract BACKGROUND: Preterm birth (PTB) has been associated with exposure to air pollution, but it is unclear if effects might vary among air pollution sources and components.

OBJECTIVES: To study the relationships between PTB and exposure to different components of air pollution, including gases and particulate matter (PM) by size fraction, chemical composition and sources.

METHODS: Fine and ultrafine PM (respectively, PM2.5 and PM0.1) by source and composition were modeled across California over period 2000-2008. Measured PM2.5, nitrogen dioxide and ozone concentrations were spatially interpolated using empirical Bayesian kriging. Primary traffic emissions at fine-scale were modeled using CALINE4 and traffic indices. Data on maternal characteristics, pregnancies, and birth outcomes were obtained from birth certificates. Associations between PTB (n= 442,314) and air pollution exposures defined according to the maternal residence at birth were examined using a nested matched case-control approach. Analyses were adjusted for maternal age, race/ethnicity, education and neighborhood income.

RESULTS: Adjusted odds ratios for PTB in association with interquartile range (IQR) increases in average exposure during pregnancy were 1.133 (95% CI: 1.118, 1.148) for total PM2.5, 1.096 (95% CI: 1.085, 1.108) for ozone, and 1.079 (95% CI: 1.065, 1.093) for nitrogen dioxide. For primary PM, the strongest associations per IQR by source were estimated for onroad gasoline (9-11% increase), followed by onroad diesel (6-8%) and commercial meat cooking (4-7%). For PM2.5 composition, the strongest positive associations per IQR were estimated for nitrate, ammonium and secondary organic aerosols (11-14%), followed by elemental and organic carbon (2-4%). Associations with local traffic emissions were positive only when analyses were restricted to births with residences geocoded at the tax parcel level.

CONCLUSIONS: In our statewide nested case-control study population, exposures to both primary and secondary pollutants were associated with an increase in PTB.