A meta-analysis of the impact of traffic-related air pollution on health and the factors affecting exposure

Clean air is a basic requirement for health and well-being. One of the main sources of air pollution is traffic. It emits harmful pollutants including nitrogen dioxide and particulate matter. There is a large body of existing evidence regarding the public health impact of air pollution. A wide range of health problems including respiratory and cardiovascular illnesses have been found. The evidence in relation to the impact of traffic related air pollution is inconsistent therefore the aim of this paper is to provide clarity on the strength of evidence. In addition, the review will consider the impact of environmental and personal exposure factors. To identify relevant research, the database Science Direct was used along with a search strategy. This review found there is a large body of evidence in relation to air pollution from traffic, health impacts and environmental factors. Due to methodological limitations and the complexity of the interactions the strength of this evidence is mixed. Links to cardiovascular illnesses were considered the most significant. A number of environmental factors such as weather and built environment have significant impacts on traffic related air pollution levels. The review highlights the lack of comprehensive and robust evidence linking environmental factors, traffic related air pollution and health impacts. Future work should use appropriate methodologies to address these gaps.