Traffic-related Air Pollution (TRAP) and Its Exposure to Cardiorespiratory Outcomes to Active Commuters in a University Outdoor Environment

Air pollutants are a major by-product of urbanisation and motorisation of society. In lower and upper middle-income Asian countries, in cities with rapid population growth such as Malaysia, traffic emissions are responsible for almost 90% of urban air pollution, so cycling or walking outdoor can be a major route of exposure for active commuters. Our study aims to examine the association between traffic-related air pollution and cardiorespiratory health symptoms among pedestrian and cyclists in a university campus located in Selangor, Malaysia.  PM_2.5 concentrations were monitored using SidePak Personal Aerosol Monitor AM510 on weekday morning cycling and walking commutes into designated high and low-traffic areas nearby campus roadsides. Volunteers cycled (n=21) and walked (n=30) for about 60-minutes in high and low-traffic cycling and walking routes respectively. The cardiorespiratory health status of blood pressure and lung function were measured before, immediately after, after 15 minutes and after 1 hour of volunteers’ commutes. The average commute exposure to PM_2.5 was determined, and the inhaled dosage was estimated. Results showed that pedestrian are exposed to higher PM_2.5 levels than cyclists traveling in the same high-traffic areas. However, the inhalation dose per kilometre travelled, D_L (µg/km) for cyclist was observed higher compared to the pedestrian due to the ventilation rate of physical activity. We also observed that there were increase in the systolic blood pressure and lung function (force-vital capacity-FVC) of pedestrians after the exposure to high PM_2.5 concentrations at high traffic walking routes (61.6 ± 14.6 µg/m³). PM_2.5 concentrations while walking in the university campus were approximately three times higher compared to cities in Europe (26 μg m⁻³). Our observation techniques can be applied in resource-constrained countries with heavy traffic emissions that may have an impact on the health of active commuters. To characterise the exposure patterns of other traffic-related air pollutant surrogates (such as soot/black carbon and nitrogen dioxide) and their influence on acute and chronic health outcomes in different Asian traffic microenvironments, further research based on the results of our study is needed.