Probabilistic risk assessment and scenario analysis of ambient PM2.5 in Bangkok for short-term respiratory and cardiovascular diseases.

This study presents a four-year analysis of cardiopulmonary hospital admissions related to PM_2.5 exposure in Bangkok to assess the short-term effects of air pollution on health. The Monte Carlo simulation-based AirQ+ model was employed to estimate hospital admissions attributable to various PM_2.5 concentrations. The average PM_2.5 concentration was 40 ± 17 µg/m³. The monthly median contribution of PM_2.5 to total particulate matter pollution ranged from 0.40 to 0.60. Individuals were exposed to PM_2.5 levels classified as "unhealthy for sensitive groups" (36-56 µg/m³) or "unhealthy for all" (57-150 µg/m³) on approximately 50% days annually). Cardiopulmonary admissions peaked during the winter, with 5,755 to 7,000 respiratory cases and approximately 7,000 cardiovascular cases, while both conditions were least prevalent in the summer (respiratory: 4,000; cardiovascular: 5,300). The PM_2.5 concentrations mirrored this seasonal pattern, reaching approximately 50 µg/m³ in winter and decreasing to approximately 25 µg/m³ in summer. The AirQ+ simulation estimated that PM_2.5 exposure exceeding 15 µg/m³ was associated with 3,306 (95% CI: 0 -15,841) additional respiratory cases and 1,497 (95% CI: 701-6,723) additional cardiovascular cases. Conversely, a 5 µg/m³ reduction in PM2.5 levels could lead to a 22% decrease in hospital admissions for cardiopulmonary diseases, whereas a 5 µg/m³ increase could result in a 16% increase in hospitalizations.