Sri Lanka's ambient air quality has shown gradual improvement over recent decades, though concentrations remain above internationally recommended levels. The annual average population-weighted concentration of PM 2.5 declined from 33.2 micrograms per cubic meter in 2000 to 22.7 micrograms per cubic meter in 2023. While this 2023 level remains below the WHO interim target of 25 micrograms per cubic meter, it still exceeds the WHO air quality guideline of 5 micrograms per cubic meter by a considerable margin. The country's performance stands notably better than the broader South Asian regional average, which reached 40.1 micrograms per cubic meter in 2022. Despite these relative gains, urban proximity to major transport corridors continues to present exposure challenges, with 91 percent of Sri Lanka's urban population residing beyond 500 meters from highways, according to estimates from the Institute for Transportation and Development Policy.

The health consequences of ambient air pollution impose substantial mortality and economic burdens on Sri Lanka. World Bank estimates indicate that 7,261 premature deaths occurred in 2019 due to exposure to ambient PM 2.5, with McDuffie et al. (2021) attributing approximately 628 of these deaths specifically to transport tailpipe emissions. Occupational exposure presents additional risks, with at least 64 premature deaths in 2023 linked to diesel engine exhaust exposure, equivalent to roughly 3 deaths per million population. The economic costs associated with these health impacts are considerable, with World Bank estimates placing the annual cost of health damages from ambient and household PM 2.5 exposure at 24.0 billion USD in 2019, representing approximately 8 percent of GDP. This burden is somewhat lower than the Asia-Pacific regional average of 10.6 percent of GDP, yet it remains substantially higher than Sri Lanka's healthcare expenditure, which accounted for only 4.4 percent of GDP in 2022.

Sri Lanka's transport sector emissions have evolved in complex patterns relative to economic growth over the past two decades. While the country's GDP grew at an average annual rate of 5.2 percent since 2010, PM 2.5 emissions from the transport sector declined by 2.8 percent between 2000 and 2010, though the rate of decline slowed substantially to just 0.2 percent between 2010 and 2022. This trajectory contrasts sharply with emissions from other sectors, which have been growing at 1.5 percent per year since 2010. By 2022, the transport sector accounted for 45 percent of total PM 2.5 emissions in Sri Lanka, reflecting its position as the dominant source of particulate pollution. The relatively modest decoupling of transport emissions from economic growth suggests that while some efficiency gains and policy interventions have yielded results, the sector continues to represent a major contributor to the country's overall air quality challenges.

The composition of transport-related PM 2.5 emissions reveals significant shifts in modal contributions over recent years. By 2022, road transport accounted for 46 percent of transport PM 2.5 emissions (including non-exhaust sources), rail contributed 12 percent, domestic navigation represented 41 percent, and domestic aviation accounted for less than 1 percent. The share attributable to road transport decreased markedly from 73 percent in 2010 to 46 percent by 2022, reflecting both policy interventions targeting road vehicles and the rising influence of maritime sources. Within the road sector, IIASA estimates for 2025 indicate that heavy-duty vehicles generate 35 percent of PM 2.5 emissions, light-duty vehicles contribute 62 percent, motorcycles account for 2 percent, and buses represent less than 1 percent. Domestic navigation has emerged as an increasingly important emission source, with its share of total transport PM 2.5 emissions rising from 15 percent in 2010 to 41 percent by 2022, with large vessels responsible for 100 percent of maritime PM 2.5 emissions according to IIASA's 2025 estimates.

Beyond tailpipe emissions, non-exhaust sources constitute a growing proportion of road transport pollution in Sri Lanka. By 2022, PM 2.5 emissions from resuspended dust, brake wear, and tire wear contributed 31 percent of road sector emissions, representing a substantial increase from 18 percent in 2010. This shift underscores the changing nature of transport pollution as cleaner exhaust technologies are adopted but vehicle activity and road conditions continue to generate particulate matter through mechanical processes. The rising contribution of non-exhaust sources suggests that comprehensive air quality strategies must address not only vehicle emission standards but also road surface management, traffic patterns, and the physical characteristics of the vehicle fleet.

Nitrogen oxide emissions from Sri Lanka's transport sector have followed a trajectory distinct from particulate matter, with growth in the early 2000s followed by a subsequent decline. NOx emissions from transport grew at 1.1 percent annually between 2000 and 2010, then declined at 2.7 percent per year from 2010 to 2022. In contrast, NOx emissions from other sectors increased at 0.8 percent annually since 2010. By 2022, the transport sector was responsible for 49 percent of total NOx emissions in the country. Road transport dominated this contribution at 83 percent, rail accounted for 3 percent, domestic navigation represented 14 percent, and domestic aviation less than 1 percent. The share of road transport in total transport NOx emissions decreased from 92 percent in 2010 to 83 percent by 2022, while domestic navigation's share increased from 4 percent to 14 percent over the same period. Within the road sector, IIASA estimates for 2025 show heavy duty vehicles responsible for 59 percent of NOx emissions, light duty vehicles contributing 40 percent, buses accounting for 1 percent, and motorcycles less than 1 percent.

Sulfur oxide emissions present a markedly different pattern, with maritime transport overwhelmingly dominant and emissions exhibiting opposite trends compared to other pollutants. SOx emissions from the transport sector declined by 0.3 percent between 2000 and 2010, then increased dramatically at 7.2 percent annually from 2010 to 2022, even as SOx emissions from other sectors declined at 1.9 percent per year since 2010. By 2022, the transport sector accounted for just 5 percent of total SOx emissions in Sri Lanka. However, within the transport sector itself, domestic navigation contributed 99 percent of SOx emissions, while road transport represented merely 1 percent, rail less than 1 percent, and domestic aviation less than 1 percent. The share of domestic navigation in total transport SOx emissions increased from 87 percent in 2010 to 99 percent by 2022, reflecting both the sulfur content of marine fuels and the absence of stringent emission controls for domestic vessels. The near-total dominance of maritime sources indicates that SOx mitigation strategies must focus primarily on fuel quality standards and vessel technology in the shipping sector.

Additional transport pollutants exhibit varied trends that reflect the sector's evolving technology and fuel use patterns. Methane emissions from the transport sector grew at 0.5 percent annually between 2000 and 2010, then at 0.8 percent from 2010 to 2022, with road transport accounting for 99 percent of transport CH4 emissions by 2022. Non-methane volatile organic compound emissions from transport declined at 1.4 percent between 2000 and 2010 and at 0.2 percent from 2010 to 2022, with the road sector similarly representing 99 percent of transport NMVOC emissions by 2022. Black carbon emissions showed more substantial declines, falling at 4.4 percent annually between 2000 and 2010 and at 3.2 percent from 2010 to 2022. By 2022, road transport contributed 67 percent of transport BC emissions (including non-exhaust sources), rail 1 percent, domestic navigation 32 percent, and domestic aviation less than 1 percent. The share of road transport in BC emissions decreased from 91 percent in 2010 to 67 percent by 2022, while domestic navigation's contribution increased from 8 percent to 32 percent over the same period.

Sri Lanka's transport sector remains almost entirely dependent on petroleum products, with minimal diversification into alternative energy sources. In 2023, the road sector contributed approximately 98 percent of total transport energy consumption, while rail, domestic navigation, and domestic aviation accounted for 1 percent, 1 percent, and less than 1 percent respectively. Oil products constituted 100 percent of transport sector energy consumption in 2023, unchanged from 2010 and 2015 levels. By 2023, biofuels and electricity represented near zero percent of energy consumption in Sri Lanka's transport sector, indicating negligible penetration of alternative fuels despite growing global momentum toward energy transition in transportation. This near-complete reliance on fossil fuels perpetuates both air quality challenges and climate vulnerabilities, while limiting the sector's resilience to petroleum price volatility and supply disruptions.

Government expenditure on fossil fuel subsidies in the transport sector imposes fiscal burdens and generates additional environmental and health costs. Between 2010 and 2015, fossil fuel subsidies in transport averaged approximately 1.1 billion USD annually, declining to 794 million USD annually from 2016 to 2023. These implicit subsidies carry external costs to Sri Lankan society beyond direct fiscal outlays, with 37 percent of these additional costs manifesting as increased local air pollution. Fossil fuel subsidies artificially reduce the cost of polluting activities, thereby discouraging investment in cleaner technologies and behavioral shifts toward less emission-intensive transport modes. The persistence of these subsidies constrains fiscal space for investments in sustainable transport infrastructure and public health systems while perpetuating the air quality burden documented through mortality and morbidity statistics.

Electric vehicle adoption in Sri Lanka has shown recent growth, though it remains modest in absolute terms and highly concentrated in specific vehicle categories. The value of EV imports reached 116 million USD between 2017 and 2024, representing 46 percent of total road vehicle imports by 2024. The composition of these imports reflects consumer preferences and policy incentives, with light duty vehicles accounting for 71 percent, two-wheelers representing 27 percent, and goods vehicles and buses comprising 2 percent. UNEP's E-mobility Readiness Index assigns Sri Lanka a score of 64 out of 100, with component scores of 13 in technology and market, 15 in policy, 21 in energy, and 15 in financial instruments. These metrics suggest moderate readiness for electric mobility transition, with relative strengths in energy infrastructure but continued gaps in policy frameworks, market development, and financial mechanisms. The relatively higher share of EVs in total vehicle imports indicates shifting consumer sentiment and import policy effectiveness, though the absolute scale remains insufficient to meaningfully alter the sector's overall emissions profile.

Rising motorization rates and inadequate public transport access create conditions that perpetuate transport-related air pollution in Sri Lanka. Motorization reached 345 vehicles per thousand population in 2024, up from 290 in 2000, exceeding the Asia-Pacific average of 317 vehicles per thousand population in 2024. This rapid expansion of private vehicle ownership reflects both economic development and the absence of viable public transport alternatives in many areas. Among the 16 urban agglomerations in Sri Lanka, only 6 percent achieved an access level of 50 percent or better, meaning that in 63 percent of cities, eight out of every ten residents lack convenient access to public transport (defined as residence within 500 meters of public transport). This structural deficit in public transport provision effectively compels private vehicle ownership and use, driving continued growth in emissions despite improvements in vehicle technology and fuel quality. The combination of high motorization and poor public transport coverage establishes conditions where emission reductions from technological improvements are offset by increased vehicle activity and congestion.

EV mandates/ procurement

Railway electrification

Vehicle scrappage scheme

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