|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.|
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.