PM2.5 and PM10 in industrial-suburban Chonburi, Thailand: Seasonal patterns and modeled mortality indicators

Ambient particulate matter remains an important environmental health concern, with concentrations influenced by interactions among diverse emission sources and seasonal meteorological conditions. Mixed land-use industrial-suburban areas within Thailand's Eastern Economic Corridor, where industrial activities, transportation, residential expansion, agriculture, coastal influences, and tourism coexist, remain relatively underrepresented in long-term air pollution studies. This study characterized temporal variation in PM 2.5 and PM 10 , their relationships with meteorological conditions, seasonal changes in the PM 2.5 /PM 10 ratio, and relative mortality indicators derived from published exposure–response models using ambient monitoring data collected in Chonburi Province, Thailand, between 2019 and 2023. PM 2.5 and PM 10 exhibited clear seasonal variation, with the highest concentrations during the cool season (30.13 ± 3.19 and 68.60 ± 5.41 µg m⁻³, respectively) and the lowest during the rainy season (14.85 ± 4.28 and 38.92 ± 7.54 µg m⁻³, respectively). The PM 2.5 /PM 10 ratio was significantly lower during the rainy season (0.34±0.03) than during summer (0.44±0.04) and the cool season (0.45±0.04), indicating seasonal shifts in particle-size composition. Atmospheric pressure was positively associated with both particulate fractions, whereas relative humidity, rainfall, and wind speed showed negative associations. Meteorological variables explained 55.8% of the variability in PM 2.5 and 67.5% of the variability in PM 10 in the overall regression models. Application of exposure–response models indicated that periods with higher PM concentrations, particularly January, February, and the cool season, were consistently associated with higher model-derived relative mortality indicators. This study characterizes long-term seasonal particulate matter dynamics in a mixed land-use industrial-suburban environment and identifies recurring periods of elevated PM concentrations that were consistently associated with higher model-derived relative mortality indicators. These findings may provide useful information for seasonally targeted air-quality surveillance, risk communication, and pollution management in similar mixed land-use industrial-suburban environments.