High-resolution monthly PM2.5 and PM10 data and annual average Pb from multiple monitoring sites across Bangkok, Thailand with an integrated screening-level health risk assessment.

Air pollution - the leading environmental threat to human health originates from natural and human sources that emit particles with PM2.5, PM10 and other toxic compounds as lead escalating alongside industrialization, urban growth and economic expansion. This study conducts the assessment for annual monitoring and health risk of PM2.5, PM10, and lead in ambient air across Bangkok, during 2021. Hourly PM data from 12 Pollution Control Department stations (7 residential, 5 roadside) and Pb measurements collected from 11 stations. Peak average values occurred at the Kanchanaphisek Road station (PM10 = 114.5 μ g /m 3 in February; PM2.5 = 56.9 μ g/m 3 in January), exceeding both Thai standards (120 μ g/m 3 and 37.5 μ g/m 3 ) and WHO 2021 guidelines (45 μ g/m 3 and 15 μ g/m 3 ). The mean Pb concentration , calculated from the station-specific averages of 11 air quality monitoring stations, was 0.041 μ gm 3 (range 0.006-0.27 μ gm 3 ), remaining well below the WHO guideline value of 0.5 μ g/m 3 . A screening-level non-carcinogenic health risk assessment was conducted using the USEPA methodology based on hazard quotient (HQ) calculations. The HQ results indicated that PM10 posed potential health risks (HQ ≥ 1) for the sensitive population at roadside stations (03t and 54t), while PM2.5 was associated with potential health risks (HQ ≥ 1) for the sensitive population across all air quality monitoring stations. In contrast, HQ values for Pb in both sensitive and general populations, as well as HQ values for PM2.5 and PM10 in the general population, remained below the risk threshold (HQ<1), indicating no adverse health effects at the screening level. These findings highlight PM2.5 and PM10 as significant health threats in Bangkok, requiring environmental strategies to protect sensitive populations.