Health implications local government should consider when planning new or expanded road systems

It has often caused me to smile wryly when I read of councils on the NSW North Coast targeting smokers lighting up and at taxi stands and bus stops, given the noticeable amount of air pollution produced by traffic along highways, main roads and other heavy traffic areas within the region.

So it was interesting to find that air pollution from nearby roads is thought to carry the risk of adverse impacts on pregnant women and the babies they carry - possibly due to the chemical toxins in traffic pollutants or because of disturbed sleep due to traffic noise.

The study quoted below was conducted in south-east Queensland where residents have similar housing and lifestyles to people living on the North Coast.

Increased traffic exposure and negative birth outcomes: a prospective cohort in Australia [Adrian G Barnett, Kathryn Plonka, W. Kim Seow, Lee-Ann Wilson, Craig Hanse,2010]

Background

Exposure to air pollution during pregnancy has been shown to increase the risk of negative birth outcomes such as pre-term birth and low birth weight [1–4]. Although the increased risks are relatively small [5–7], the public health implications are large because exposure to some level of air pollution is ubiquitous in urban areas, and pre-term and low weight babies: stay in hospital longer after birth, have an increased risk of death, and are more likely to develop disabilities [8–10]. Many of the estimated associations between air pollution and birth outcomes have relied on the temporal variation in pollution, but pollution also varies spatially [11]. Pollution levels in a city are generally higher in areas with lots of traffic and industrial areas. Temporal studies also rely on a fixed network of pollution monitors, and these monitors can often be far from subjects' homes. Ignoring the spatial variability in pollution therefore introduces a measurement error that may lead to regression dilution [12]. A study in Brisbane showed a clear strengthening of the association between increased pollution and small fetus size when reducing this measurement error by using pollution monitors closer to women's homes [6]. Studies in Spain have attempted to reduce measurement error by restricting analysis to those women who spent more time at home (where their pollution exposure was estimated), and found stronger associations between pollution exposure and fetal growth and birth weight [7,13]. Another reason for taking a spatial approach in this study was the public interest created by our previous study showing restricted fetal development due to increased air pollution exposure in Brisbane, Australia [6]. A common concern was the distance between the home and a busy road at which health effects occurred. This distance also has implications for council authorities looking to build or expand roads. By examining traffic exposure around the home we aimed to find the distance at which the majority of the negative impacts on birth outcomes occurred. Although levels of air pollution in South East Queensland are low compared with industrial cities, the population's exposure is relatively high due to an outdoor lifestyle and buildings that are highly permeable [14]. Many homes in Queensland are built to capture breezes in order to give relief from high summer temperatures. But this design also increases their exposure to traffic pollution. People living near major roads, and particularly major road junctions where the traffic often stops, will experience the highest levels of exposure…..

Conclusions Pregnant women should reduce their exposure to traffic. A reduction in traffic emissions, whether through improved vehicle technology or increased public transport use, would have immediate health benefits by giving children a better start to life.