Traffic-related Air and Noise Pollution, Birth Outcomes and Infant Mortality in London

Abstract

Introduction Traffic pollution comprises toxic air pollutants and noise. Air pollution has been associated with infant mortality, and there is also evidence for small effects on birth weight. Research on noise and birth outcomes is limited, but an association with low birthweight is suggested. This study investigates traffic-related air and noise pollution exposures in relation to birth outcomes and infant mortality. Methods The study population comprises 882713 live births and 5452 stillbirths in the Greater London area from 2003-2010. Monthly concentrations of primary traffic air pollutants (NO2, NOx, exhaust and non-exhaust PM2.5 and PM10) and regional/urban background air pollutants (Ozone, and total PM2.5 and PM10) have been estimated using a dispersion model at 20m x 20m resolution. Time-weighted average air pollution estimates at address-level have been calculated for pregnancy and post-natal time windows. Annual road traffic noise levels have been modeled at address-level using the TRAffic Noise EXposure (TRANEX) model. We are analysing the relationship between air pollutant/noise exposures and birth weight, small-for-gestational-age (SGA), stillbirth and infant mortality, adjusting for potential confounders (e.g. maternal age, smoking and deprivation). Results Mean time-weighted average pregnancy exposures were 75μg/m3 for NOx, 15μg/m3 for PM2.5 and 24μg/m3 for PM10, and mean noise exposures were 58dB (day-time) and 53dB (night-time). Preliminary results suggest that traffic-related air pollution and noise exposures during pregnancy are independently associated with reduced mean birth weight and elevated risk of SGA. Conclusions The study is in progress and will be the largest to date examining environmental noise exposures and birth outcomes. This study combines highly spatially refined address-level exposure assessment for both noise and air pollutants, and will improve understanding of the relative influences of these co-exposures upon fetal/infant health.