Spatial and temporal PM2.5 emission source assessment in Ratchaburi using high-resolution national data

Thailand has been grappling with air pollution problems for over a decade. In 2024, Ratchaburi was identified as the province with the highest level of air pollution in Thailand, particularly the high concentration of PM2.5. However, little is known about the PM2.5 emission sources in Ratchaburi and neighboring provinces that could influence their air quality. This study aims to identify the key sources of PM2.5 emissions in Ratchaburi using the high-resolution emission inventory developed for Thailand. In 2019, the total PM2.5 emissions in the province amounted to 2,056 tons. The top three key emission sectors were identified to include the agricultural sector (47%), followed by non-industrial combustion plants (20%), and road transport (15%). Agricultural emissions, particularly from the open burning of crop residues and livestock/manure management, were the largest contributors to PM2.5 emissions, especially during the dry season. District-level analysis revealed that sugarcane and rice residue burning were the primary contributors in several districts, notably Chom Bueng, Pak Tho, and Photharam. Forest fires, while less significant overall, were prominent in districts with substantial forest areas such as Chom Bueng and Suan Phueng. The study also found that non-industrial combustion emissions from fuelwood cooking stoves and biomass-based power plants significantly impacted air quality. Seasonal variations in emissions were observed, with peak emissions occurring during the dry season due to increased agricultural activities and forest fires. This research highlights the importance of addressing the major sources of PM2.5 emissions in Ratchaburi, including adopting cleaner agricultural practices, promoting alternative waste management technologies, and implementing measures to control forest fires. The findings of this study provide valuable insights for policymakers to develop effective strategies to mitigate air pollution and improve public health in the region.