Brunei Darussalam, a high-income economy in Southeast Asia with a population of 463,000 and a GDP per capita of $90,007 in 2024, faces a distinctive air quality challenge that reflects both its small size and its development trajectory. The annual average concentration of PM 2.5—fine particulate matter that poses significant health risks—decreased from 9.0 micrograms per cubic meter in 2000 to 7.6 micrograms per cubic meter in 2023. While this level exceeds the World Health Organization's air quality guideline of 5 micrograms per cubic meter, it remains well below the WHO's interim target of 25 micrograms per cubic meter and significantly lower than the Southeast Asian regional average of 20.2 micrograms per cubic meter recorded in 2022. According to the State of Global Air, transport and international shipping contributed approximately 13.1 percent and 2.7 percent, respectively, to ambient PM 2.5 concentrations in 2019, underscoring the sector's material—though not dominant—role in the country's air pollution profile.

The health and economic consequences of air pollution in Brunei Darussalam, while modest in absolute terms compared to regional peers, nonetheless warrant serious policy attention. World Bank estimates indicate that 39 people died prematurely due to exposure to ambient PM 2.5 in 2019, with McDuffie et al. (2021) attributing approximately six of these deaths specifically to transport tailpipe emissions. The annual cost of health damages from ambient and household PM2.5 exposure totaled $291 million in 2019, equivalent to approximately 1 percent of GDP—a considerably lower proportion than the Asia-Pacific regional average of 10.6 percent. For context, Brunei Darussalam allocated 1.8 percent of GDP to healthcare expenditures in 2022, suggesting that air pollution's health burden, while not negligible, remains manageable within the country's fiscal framework. Nevertheless, these figures mask the preventable nature of pollution-related mortality and morbidity, particularly that attributable to the transport sector.

Brunei Darussalam's transport emissions profile indicates a sector in gradual decline, though it continues to contribute substantially to the country's overall pollution burden. Between 2000 and 2010, PM 2.5 emissions from transport declined by 0.8 percent annually, with the rate of reduction accelerating to 2.2 percent per year between 2010 and 2022—a period during which the country's GDP grew at an average of 1.5 percent annually. By 2022, the transport sector accounted for 25 percent of total PM 2.5 emissions in the country, a figure that reflects both the sector's emissions trajectory and the concurrent growth in emissions from other sectors, which increased by 2.3 percent annually since 2010. Road transport dominates the emissions landscape entirely, contributing 100 percent of transport-related PM 2.5, with no measurable contributions from rail, domestic navigation, or domestic aviation—a pattern consistent with the country's transport infrastructure and geographic characteristics. Within the road sector, heavy-duty vehicles account for an estimated 93 percent of PM2.5 emissions in 2025, compared with 6 percent from light-duty vehicles, 1 percent from motorcycles, and negligible contributions from buses.

The composition of road sector emissions has evolved in ways that complicate mitigation strategies. By 2022, non-exhaust sources—specifically resuspended dust, brake wear, and tire wear—contributed 37 percent of road-sector PM2.5 emissions, up from 25 percent in 2010. This shift reflects both the effectiveness of efforts to reduce exhaust emissions and the growing challenge posed by non-combustion particulate sources, which remain difficult to address through conventional regulatory approaches. The transport sector's nitrogen oxide (NOx) emissions followed a similar downward trajectory, declining by 1.1 percent annually between 2000 and 2010 and by 1.6 percent between 2010 and 2022, though the sector still accounted for 42 percent of total national NOx emissions by 2022. As with PM 2.5, road transport represents the entirety of transport NOx emissions, with heavy-duty vehicles responsible for 90 percent of the sector's output. Sulfur oxide (SOx) emissions from transport showed more dramatic reductions, falling by 16.3 percent annually between 2000 and 2010 and by 12.4 percent between 2010 and 2022, though the transport sector's share of total SOx emissions remains negligible at less than 1 percent by 2022.

Other transport-related pollutants demonstrate similarly declining trends, albeit from low baseline levels. Methane (CH4) emissions from transport decreased by 0.2 percent annually between 2000 and 2010 and by 1.4 percent between 2010 and 2022, with the road sector accounting for all transport-related methane emissions by 2022. Non-methane volatile organic compounds (NMVOC) declined by 2.4 percent annually in the first period and by 0.6 percent in the second, while black carbon (BC) emissions—a particularly harmful component of particulate pollution—fell by 1.5 percent annually between 2000 and 2010 and by a more substantial 3.7 percent between 2010 and 2022. These reductions reflect improvements in fuel quality, vehicle technology, and fleet composition, although the persistence of heavy-duty vehicles as the primary source of emissions suggests that targeted interventions in the freight sector could yield significant additional benefits.

Brunei Darussalam's transport energy consumption patterns reveal a sector characterized by near-total dependence on petroleum products and minimal diversification into alternative fuels. In 2023, the road sector accounted for 99 percent of total transport energy consumption, with domestic aviation contributing a marginal 1 percent and rail and domestic navigation effectively absent from the energy mix. Oil products constituted 100 percent of transport sector energy consumption in 2023, unchanged from 2010 and 2015, while biofuels and electricity each represented 0 percent of the fuel mix. This lack of fuel diversity is sustained in part by substantial fossil fuel subsidies, which totaled approximately $1.1 billion between 2010 and 2015 and increased to $1.2 billion between 2016 and 2023. These subsidies impose additional external costs on Brunei Darussalam's society, with an estimated 20 percent of these costs manifesting as increased local air pollution—a policy contradiction that simultaneously undermines air quality objectives and perpetuates fossil fuel dependence.

The transition to electric vehicles in Brunei Darussalam remains nascent but is beginning to gather momentum. Between 2017 and 2024, electric vehicle imports reached $9 million, representing 3 percent of total road vehicle imports by 2024. The composition of these imports skews heavily toward light-duty vehicles, which account for 97 percent of the total, with two-wheelers contributing 2 percent and goods vehicles and buses remaining negligible. The United Nations Environment Programme's E-mobility Readiness Index assigns Brunei Darussalam a score of 59 out of 100, with component scores of 11 for technology and market, 20 for policy, 20 for energy infrastructure, and 8 for financial instruments. These scores suggest that while basic enabling conditions exist, significant gaps remain in policy frameworks, market development mechanisms, and financial incentives necessary to accelerate electric vehicle adoption at scale.

Brunei Darussalam's broader transport landscape reflects the challenges of motorised society with limited public transport alternatives. Motorization stood at 648 vehicles per thousand population in 2024, up from 637 in 2000 and well above the Asia-Pacific average of 317 vehicles per thousand population. This high level of vehicle ownership, combined with relatively low fuel costs sustained by subsidies, creates structural barriers to modal shift and emissions reduction. The country's public transport infrastructure remains underdeveloped: rapid transit coverage increased from 0.0 kilometers per million urban population in 2015 to just 0.2 kilometers by 2024, and in 100 percent of Brunei Darussalam's urban agglomerations, eight out of ten residents lack convenient access to public transport. This absence of viable alternatives to private vehicle use reinforces patterns of car dependency and limits the potential effectiveness of demand-side measures to reduce transport emissions. Addressing air pollution from transport in Brunei Darussalam will thus require coordinated interventions spanning vehicle technology standards, fuel quality improvements, subsidy reform, electric mobility incentives, and—perhaps most fundamentally—investments in public transport infrastructure that can offer residents genuine alternatives to private car ownership.

EV mandates/ procurement

Managing transport air pollution

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