Active Commuters’ Exposure to PM2.5, Black Carbon, Noise, and Heat During the Northeast Monsoon in Selected Urban Cities in Malaysia

Today, more than 70% of the Malaysian population lives in urban areas, and this proportion continues to increase. Changes in land use and land cover, as well as additional anthropogenic factors, have altered the energy balance and led to spatio-temporal variations in urban climate. Active commuters who travel near roadways with high traffic density face a range of exposures, such as traffic-related air pollution (TRAP), traffic noise (TN), and urban heat (UHI). As urbanisation and population acceleration increase, understanding the environmental stressors faced by active commuters becomes crucial. Our aim is to measure the weekly spatial and temporal variation of TRAP, TN, and UH in selected cities in Malaysia and assess the health risks of exposures. The assessment was conducted along the selected routes in Kuala Lumpur (KUL) city centre and Cyberjaya (CYB) in Malaysia. The sampling campaign was conducted in October and November 2023. This comprehensive assessment measured TRAP (i.e., PM2.5, black carbon (BC)), TN, and UH simultaneously. The TSI SidePak (AM510), microAeth (MA200), TSI Edge 5 Personal Noise Dosimeter, and QUESTemp 36 models were used to measure PM2.5, BC, TN, and UH, respectively. The preliminary findings indicate a significant difference between peak hours (morning, noon, and evening) for all parameters (p < 0.001), except for BC concentrations (p = 0.37) during weekdays. All parameters were significant (p < 0.001) during weekends in KUL (Route 1). For CYB (Route 2), there was a significant difference in PM2.5, BC, TN, and UH levels (p < 0.001) between peak hours on both weekdays and weekends. PM2.5 (73.31 µg/m3), BC (6.19 µg/m3), and TN (80.10 dB(A)) were significantly higher on weekdays in Route 1 compared to Route 2, while the heat index was also higher (27.90 °C) in Route 1. Similar findings showed higher levels of PM2.5 (85.14 µg/m3), BC (5.95 µg/m3), and TN (77.89 dB (A)) on weekends in Route 1. Our study will help to address the knowledge gap on the impact of urban heat, air pollution, and noise pollution on climate adaptation among active commuters in urban cities. The findings of this study will contribute to the development of targeted interventions and strategies to enhance the resilience of these active commuters to the adverse effects of urban stressors. Our examination will also add to the wider discussion on sustainable urban mobility, highlighting the importance of specific actions to improve the environmental conditions for those who use active modes of transport. This will eventually encourage healthier and more sustainable travel options.