National Inventory of Ammonia Emissions from Anthropogenic Sources in Thailand

Ammonia (NH3) is a key precursor to secondary particulate matter in Southeast Asia, yet Thailand has lacked a country-specific, policy-focused emission inventory. This study creates the first spatially gridded (12 × 12 km) and monthly resolved national NH3 inventory for 2019, using detailed agricultural activity data, survey-based livestock management practices, and crop-specific fertilizer application profiles. Satellite-derived burned-area data were included to constrain emissions from open burning. National NH3 emissions are estimated at 459.1 kt per year, with an overall uncertainty of ±15.3%. Agriculture accounts for 95.8% of total emissions. Livestock and manure management contribute 225.3 kt per year (49.1%), reflecting high densities of poultry, cattle, and pigs, as well as regional differences in manure handling and storage practices that enhance ammonia volatilization. Fertilizer-related emissions total 192.4 kt per year (41.9%), with seasonal peaks during primary planting cycles, in contrast to the more episodic biomass-burning emissions. Comparison with the global EDGARv8.1 inventory shows significant sectoral and temporal differences, including considerably higher livestock emissions and lower fertilizer emissions in this study, due to Thailand-specific emission factors and temporal emission allocation methods. These findings clarify the spatial and temporal drivers of NH3 emissions in Thailand and offer actionable insights for targeted mitigation—notably improved manure management and optimized nitrogen use in regions where dry-season emissions coincide with severe PM2.5 episodes. The THAI-NH3 Inventory provides a strong foundation for chemical-transport modeling and evidence-based policymaking to reduce ammonia-related haze in Thailand.