Assessing personal PM_2.5 exposure from various microenvironments among schoolchildren in Vietnam

Air pollution is an environmental threat to public health. This study aimed to assess PM_2.5 concentrations in various microenvironments and identify their influence on personal PM_2.5 exposure among schoolchildren in Vietnam. We used portable PM_2.5 monitors (AirBeam3) for personal PM_2.5 measurements of children aged 11-12 years living in two districts (defined as Group A and B) in Ho Chi Minh City, Vietnam, between December 2022 and January 2023, with children's activities recorded in diaries. Linear mixed-effects models were used to identify the influence of microenvironments on children's PM_2.5 exposure. Overall, eligible data from 64 children were included in the analysis. The median PM_2.5 concentration measured is 25 μg/m³ and average PM_2.5 concentrations peaked during 06:00-07:00 and 18:00-20:30, when traffic density is heavy. Children spent the majority of their day indoors (88.4 %). Among microenvironments, children exposed to the highest PM_2.5 concentration from home incense burning, followed by eating street food on sidewalks, commuting by motorbike, and being in school classrooms, with median concentrations ranging from 36.7 to 71.1 μg/m³. Major contributors to higher PM_2.5 exposure in children included incense burning at home (increase by 28.9 %), eating street food (21.2 %), and road commuting (21.1 %). Notably, motorbike commuting resulted in higher PM_2.5 levels than walking or cycling. Findings highlight the importance of controlling indoor air quality. Suggestions to reduce children's PM_2.5 exposure include reducing incense burning, promoting cleaner transport options, and implementing long-term urban policies, such as improving public transportation and pedestrian infrastructure.