Traffic-Related Air Pollution, Noise and Infant Mortality in London

Abstract

BackgroundThere is evidence that ambient air pollution is associated with increased risk of infant mortality. Road traffic is a major contributor to ambient air pollution, but it also generates noise. This study investigates long-term exposure to both traffic-related air and noise pollution and risk of infant mortality. MethodsWe conducted a matched case-control study of infant deaths (deaths occurring in 1st year of life) from singleton births across Greater London from 2003-2010. Controls were singleton births in the study area between 2003-2010 surviving to age 1. Cases were matched to controls (n=29) on birthdate and sex. Monthly concentrations of NO2, NOX, source-specific traffic-related PM2.5, PM2.5, PM10 and ozone were estimated at 20x20m resolution using a dispersion model, and time-weighted averages calculated for pregnancy/trimesters and birth to case death at address-level. Road traffic noise was modelled at address-level. We analysed the relationship between air pollutants/noise and infant mortality using conditional logistic regression, with adjustment for confounding. ResultsThe study population comprises 3390 infant deaths (69% neonatal, 31% postneonatal). Average air pollutant exposures for cases from birth to death were 42μg/m3 NO2, 77μg/m3 NOx, 15μg/m3 PM2.5, 24μg/m3 PM10 and 31μg/m3 O3. Average day- and night-time noise levels were 58 and 53 dB respectively. Higher road traffic air pollution and noise exposures were particularly associated with non-White ethnicity and lower socio-economic status. Preliminary results from adjusted single-pollutant models suggest increased risk of infant mortality associated with higher ozone exposure, but not with other air pollutants or noise. Analyses of joint air pollution–noise exposures are currently underway. ConclusionsTo our knowledge, this is the first epidemiological study to investigate risk of infant mortality in relation to both road traffic air pollution and noise co-exposures.