Socioeconomic influence on air pollution exposure whilst walking to school

Abstract

Exposure to traffic-related air pollution has been linked to a variety of adverse human health effects, with increased risks found among those young in age and those living in lower socioeconomic conditions. This study compares exposure to air pollution experienced by children during their walking commute to school in contrasting areas of socioeconomic status based on school decile in the urban area of Auckland, New Zealand. Four schools were selected for this study, two from a low decile (LD) area and two from a high decile (HD) area. One of each school (HD and LD) is located in the area of South Auckland (SA) and the North Shore (NS). The traffic-related air pollutants carbon monoxide (CO) and ultrafine particles (UFP) were measured while walking to school using mobile data collection equipment during simulated morning school commutes from May to June 2017. Estimates of the average vehicle fleet composition and traffic flows were made based on identification of the vehicles traveling along the walking school routes. Vehicle information associated with licence plates (make, age and engine type) was extracted using an associated database. The results show no clear correlation between socioeconomic status and air pollution exposure. The highest exposure during the school commute was observed at the SA LD site, followed by the NS HD site. The average age of vehicles was found to be higher than in other developed countries, with the LD sites recording the oldest fleet. It was further found that traffic and urban conditions influence commuting exposure, with the presence of traffic lights, the proportion of heavy vehicles, and the extent of stop-start vehicle movement considerably increasing the short-term exposure of pollutants to those walking alongside roads exhibiting these characteristics. This suggests that reducing the average car age and enhancing traffic flow during morning rush hours could be effective tools for minimising the air pollution exposure experienced by commuters and reduce the risk of spikes in UFP concentrations to which pedestrians are most at risk. This could be achieved by limiting the use of private transport for the school commute and encouraging active commute options.