Personal Exposure and Uptake of Vehicular Air Pollution while Commuting in Auckland

Abstract

Human exposure to air pollution is increasingly being linked to adverse health outcomes. However, individual exposure is poorly quantified by conventional fixed air pollutant monitoring stations as individuals are generally mobile, undergo varying levels of physical activity, and spend different amounts of time in high concentration areas such as in close proximity to major roads. It has been suggested that for many people, their main air pollution dose is received while commuting. Different modes of transport result in different personal exposure patterns because of different routes and speeds and different commute times. Also, the amount of pollutant inhaled will be reflected in the amount of physical activity involved in the various modes. In this research we take advantage of new mobile air pollution technology to investigate personal exposure and uptake of CO by measuring personal exposures while commuting through the same route but by different modes of transport namely car, bus, train, motorcycle, bicycle and running, taking into account the commute time as well as the level of physical activity required for each mode of transport. The exposures are also compared with measurements made at fixed monitoring sites in order to evaluate their representativeness. The results of the study show that the uptake of pollutants varies significantly between modes of transport. Between the motorised forms of transport, the train commuters experience the lowest levels, while motorcyclists experience the highest. Concentrations while commuting by bus are slightly lower than by private vehicle. This is more-so when there is a separate bus lane. While the average exposures to which cyclist and runners are exposed are lower than for motorised vehicles, when the increased physical activity that is required is considered (leading to high breathing rates) and the increased commute time (especially in the case of runners), the air pollution doses received by those travelling by active modes is considerably higher than for those travelling by motorised modes. This suggests that if cycling and running/walking are to be promoted as healthy commuting options, separate cycle lanes are needed to remove these commuters from the main line of traffic and reduce the levels of pollution to which they are exposed. The results of this study have potential to inform urban design especially road layout and traffic management particularly with regard to the benefits of the provision of separate cycle lanes and ways to make cycling and walking more attractive and safe modes of transport.