Assessing the impact of road traffic composition on pedestrian exposure to air pollution in urban area: Evidence from Phnom Penh Streets, Cambodia

Abstract

Road traffic is a major contributor to urban air pollution, particularly in developing cities dominated by private vehicles. This study examines the impact of traffic composition on pedestrian exposure to air pollution along a 2.1 km segment of Monivong Boulevard in Phnom Penh, Cambodia. Data were collected through two surveys—one measuring air pollution and meteorological conditions and another assessing traffic composition—during weekday peak hours on February 13, 2024. Results indicate that morning peak hours exhibited the highest Particle Number Concentration (PNC), whereas Ultrafine Particles (UFP) levels peaked in the evening due to atmospheric conditions. Regression analysis revealed strong correlations between traffic volume, vehicle types, and air pollution indicators such as PNC and Lung Deposited Surface Area (LDSA). These findings emphasize the need for sustainable transportation policies and improved traffic management to mitigate pedestrian exposure to air pollution.