Thailand faces significant air quality challenges driven substantially by its transport sector, with implications for public health and economic productivity. The country of 71.7 million people (2024) recorded an annual average population-weighted concentration of PM 2.5 at 23.5 micrograms per cubic meter in 2023, a decline from 33.9 micrograms per cubic meter in 2000. While this level falls below the WHO interim target of 25 micrograms per cubic meter, it remains nearly five times higher than the WHO air quality guideline of 5 micrograms per cubic meter. The State of Global Air estimates that transport and international shipping contributed approximately 9.1 percent and 0.9 percent respectively to ambient PM 2.5 concentrations in 2019. This transport-related pollution burden affects a substantial portion of the urban population—the Institute for Transportation and Development Policy (ITDP) estimates that only 45 percent of Thailand's urban residents live beyond 500 meters from highways, exposing the majority to elevated pollutant concentrations from road traffic.

The health consequences of transport-related air pollution impose considerable mortality and economic costs on Thailand. World Bank estimates indicate that 32,211 people died prematurely due to exposure to ambient PM 2.5 in 2019, with McDuffie et al. (2021) attributing approximately 3,263 of these premature deaths specifically to transport tailpipe emissions. Occupational exposure to diesel engine exhausts claimed at least 434 lives prematurely in 2023, equivalent to approximately 6 deaths per million population. The economic toll of ambient and household PM 2.5 exposure reached 80.9 billion USD in 2019, representing about 6 percent of Thailand's GDP—measured at 1.8 trillion USD (PPP) in 2024 with a per capita GDP of 24,708 USD. This health damage burden, while substantial, remains below the Asia-Pacific average of 10.6 percent of GDP. For context, Thailand allocated 5.4 percent of GDP to healthcare expenditure in 2022, underscoring how air pollution-related health costs approach the scale of the nation's entire healthcare budget.

Thailand's transport sector emissions trajectory reveals a complex pattern of growth and decline across different pollutants, shaped by economic expansion and evolving vehicle composition. Since 2010, Thailand's GDP has grown at an average annual rate of 5.0 percent, while PM 2.5 emissions from transport declined by 4.8 percent annually between 2000 and 2010 before growing modestly by 0.5 percent annually between 2010 and 2022. By 2022, the transport sector accounted for 19 percent of total PM 2.5 emissions in Thailand, with road transport contributing 80 percent of transport-related PM 2.5 (including non-exhaust emissions), domestic navigation 14 percent, rail 6 percent, and domestic aviation 1 percent. The road transport share decreased from 87 percent in 2010, while domestic navigation's contribution more than doubled from 6 percent to 14 percent over the same period. Within the road sector, IIASA estimates that heavy-duty vehicles generate 80 percent of PM 2.5 emissions in 2025, with light-duty vehicles contributing 12 percent, buses 6 percent, and motorcycles 2 percent. Non-exhaust emissions from resuspended dust, brake wear, and tire wear have grown in importance, representing 29 percent of road sector PM 2.5 emissions by 2022, up from 19 percent in 2010.

​Nitrogen oxide and sulfur oxide emissions demonstrate distinct patterns reflecting changes in fuel composition, vehicle technology, and modal distribution. NOx emissions from transport declined by 0.7 percent annually between 2000 and 2010, then grew by 1.3 percent annually between 2010 and 2022, while other sectors reduced NOx emissions by 0.4 percent per year since 2010. By 2022, transport accounted for 56 percent of total NOx emissions in Thailand, with road transport contributing 94 percent of transport NOx, domestic navigation 3 percent, domestic aviation 2 percent, and rail 1 percent. The road share declined slightly from 96 percent in 2010, while domestic navigation increased from 2 percent to 3 percent. Heavy-duty vehicles dominate road sector NOx emissions at 79 percent in 2025, followed by light-duty vehicles at 13 percent, buses at 7 percent, and motorcycles at 1 percent, according to IIASA estimates. Sulfur oxide emissions show more dramatic shifts: transport SOx emissions declined by 7.7 percent annually between 2000 and 2010 but grew by 6.4 percent annually between 2010 and 2022. By 2022, transport represented only 3 percent of total SOx emissions, with domestic navigation dominating at 89 percent of transport SOx, domestic aviation contributing 8 percent, and road transport just 3 percent—a striking decline from 13 percent in 2010.

Transport emissions of methane, non-methane volatile organic compounds, and black carbon reveal sector-specific patterns with road transport maintaining overwhelming dominance. Methane emissions from transport grew by 1.2 percent annually between 2000 and 2010, then declined by 1.0 percent annually between 2010 and 2022, with road transport accounting for 99 percent of transport CH4 emissions by 2022. Non-methane volatile organic compound (NMVOC) emissions declined by 3.4 percent annually between 2000 and 2010 before growing by 0.5 percent annually between 2010 and 2022, similarly concentrated in the road sector at 99 percent of transport NMVOC emissions. Black carbon emissions from transport declined by 6.1 percent annually between 2000 and 2010 and continued declining by 0.8 percent annually between 2010 and 2022. By 2022, road transport contributed 91 percent of transport black carbon emissions (including non-exhaust sources), domestic navigation 8 percent, rail 0 percent, and domestic aviation 0 percent. The road share decreased from 96 percent in 2010, while domestic navigation's contribution nearly tripled from 3 percent to 8 percent, reflecting growing maritime activity and potentially slower progress in marine emission controls.

Thailand's transport sector energy consumption remains heavily dominated by oil products, though modest shifts toward alternative fuels have emerged in recent years. In 2023, the road sector consumed approximately 96 percent of total transport energy, with domestic aviation accounting for 4 percent and rail and domestic navigation each contributing negligible shares. Oil products constituted 90 percent of transport sector energy consumption in 2023, rising from 89 percent in 2010 and 82 percent in 2015, indicating deepening fossil fuel dependence despite global decarbonization trends. Biofuels and electricity represented 6 percent and 0 percent respectively of transport energy consumption by 2023. The rail sector shows notable electrification progress: electricity consumption increased from approximately 7 percent in 2010 to 29 percent by 2023. However, Thailand's grid emission factor stood at 555 grams of CO2 per kilowatt-hour in 2024—comparable to the Asia-Pacific average of 559 but below Southeast Asia's 583—limiting the climate benefits of electrification. Thailand's grid carbon intensity improved by just 0.8 percent annually since 2015, lagging behind the broader Asia-Pacific improvement rate of 1.4 percent per year.

​Fossil fuel subsidies and taxation structures present conflicting fiscal pressures with implications for transport emissions and government revenues. Between 2016 and 2023, fossil fuel subsidies averaged approximately 435 million USD annually, imposing additional external costs on Thai society with an estimated 44 percent of these costs manifesting as increased local air pollution. These subsidies effectively incentivize continued fossil fuel consumption in the transport sector while generating health and environmental damages. Conversely, fuel tax revenues comprise approximately 4 percent of Thailand's total government revenue, creating fiscal vulnerability as transport electrification progresses and potentially erodes this revenue base. This structural tension between implicit subsidy expenditures that worsen air pollution and tax revenues dependent on fossil fuel consumption underscores the need for comprehensive fiscal reform that aligns economic incentives with public health and environmental objectives while securing alternative revenue sources to replace declining fuel tax receipts.

Thailand has experienced rapid growth in electric vehicle imports, positioning the country as an emerging hub for transport electrification in Southeast Asia. The value of EV imports reached 6.6 billion USD between 2017 and 2024, representing 50 percent of total road vehicle imports by 2024—a remarkable market transformation within less than a decade. Light-duty vehicles comprise 97 percent of these EV imports, with goods vehicles and buses contributing 2 percent and two-wheelers essentially negligible at 0 percent. UNEP's E-mobility Readiness Index assigns Thailand a score of 82 out of 100, with subscores of 20 for technology and market, 20 for policy, 20 for energy, and 22 for financial instruments, indicating relatively balanced readiness across key enabling dimensions. However, this electrification progress occurs within a broader context of rising motorization: vehicle ownership reached 600 vehicles per thousand population in 2024, up from 514 in 2000 and nearly double the Asia-Pacific average of 317 vehicles per thousand population in 2024. This motorization surge risks offsetting emission reduction gains from vehicle electrification through increased total vehicle kilometers traveled and associated congestion.

​Public transport infrastructure development has lagged significantly behind motorization growth, constraining modal shift opportunities that could reduce transport emissions and air pollution. Thailand added rapid transit infrastructure at a modest pace, expanding from 2.1 kilometers of rapid transit per million urban population in 2015 to 3.8 kilometers by 2024. Among Thailand's 32 urban agglomerations, 63 percent of cities suffer from inadequate public transport coverage—in these cities, eight out of ten residents lack convenient access to public transport. This infrastructure deficit forces urban residents toward private vehicle dependence, increasing road traffic emissions and population exposure to transport-related air pollution. The concentration of population near highways compounds this problem: with only 45 percent of urban residents living more than 500 meters from highways, the majority face sustained exposure to traffic-related pollutants even if they do not own vehicles themselves. Expanding rapid transit networks and improving public transport accessibility across Thailand's urban centers represents a critical intervention pathway for reducing both transport emissions and population exposure to air pollution, while simultaneously addressing traffic congestion and enhancing urban mobility equity.

Ban of ICE sales

EV mandates/ procurement

Managing transport air pollution

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