Particulate Matter Emissions at Different Microenvironments Using Low-Cost Sensors in Megacity Dhaka, Bangladesh

The global challenge of air pollution’s adverse health effects, particularly highlighted in Dhaka, Bangladesh, underscores the significant impact of particulate matter (PM) exposure. This study aims to assess the current sources of PM_2.5 emissions in different microenvironments around Dhaka and explore potential risk factors to assess individual 24 h exposure to PM_2.5. A commercially available low-cost sensor was utilized for collecting data for 15 days under various environmental conditions. The average concentrations for PM_1.0, PM_2.5, and PM₁₀ were 37.05 ± 24.36 µg/m³, 57.22 ± 40.75 µg/m³, and 69.22 ± 48.46 µg/m³, respectively. The highest PM_2.5 concentrations were found (78.87 ± 53.69 μg/m³) in restaurants and residences (62.35 ± 41.70 μg/m³), while air-conditioned shopping malls exhibited the lowest concentrations (20.08 ± 15.57 μg/m³). Driving with windows closed and utilizing air conditioning resulted in a 33–52% reduction in PM_2.5 concentrations inside the car. The Hazard Quotient (HQ) for PM_2.5 varied by location, with a low level observed in the air-conditioned locations and a moderate level observed in restaurants and non-air-conditioned shopping malls. The significance of this study lies in its potential to inform public health strategies and urban planning initiatives aimed at reducing air pollution exposure in highly populated cities like Dhaka.