The Solomon Islands faces a growing challenge in managing transport-related air pollution, which has emerged as a significant public health and environmental concern for this Pacific island nation of approximately 819,000 people. While the country's air quality indicators remain relatively favorable compared to global standards, the health and economic costs associated with particulate matter exposure reveal the urgent need for targeted policy interventions in the transport sector.

Air quality monitoring data shows that the annual average population-weighted concentration of PM 2.5 in the Solomon Islands increased from 9.2 micrograms per cubic meter in 2000 to 9.8 micrograms per cubic meter in 2023. Although this level remains below the WHO interim target of 25 micrograms per cubic meter, it exceeds the WHO air quality guideline of 5 micrograms per cubic meter, indicating room for improvement in air quality management. The country's PM 2.5 levels are notably higher than the Pacific Islands regional average of 5.8 micrograms per cubic meter recorded in 2022, suggesting that local emission sources, particularly from the transport sector, play a meaningful role in ambient air pollution.

The health burden of transport-related air pollution in the Solomon Islands is substantial. World Bank estimates indicate that 109 people died prematurely due to exposure to ambient PM 2.5 in 2019, with approximately 4 of these deaths attributable to transport tailpipe emissions according to McDuffie et al. (2021). The State of Global Air estimates that transport and international shipping contributed about 0.8 percent and 3.1 percent to ambient PM 2.5 levels, respectively, in 2019. Occupational exposure to diesel engine exhausts presents an additional health risk, with at least 3 premature deaths recorded in 2023, equivalent to approximately 4 deaths per million population. The economic consequences of these health impacts are considerable: the World Bank estimated that the annual cost of health damages due to ambient and household PM 2.5 exposure amounted to 214 million USD in 2019, representing approximately 13 percent of the country's GDP. This burden exceeds both the Asia-Pacific regional average of 10.6 percent of GDP and the Solomon Islands' own healthcare expenditure, which stood at 4.8 percent of GDP in 2022.

The transport sector has become the dominant source of PM 2.5 emissions in the Solomon Islands, accounting for 66 percent of total emissions by 2022. This represents a significant shift in the country's emissions profile, driven by changing economic activity and sectoral growth patterns. Between 2000 and 2010, PM 2.5 emissions from transport grew by 0.9 percent annually, but this trend reversed between 2010 and 2022, with emissions declining by 3.3 percent per year. Meanwhile, PM 2.5 emissions from other sectors have been declining by 0.4 percent annually since 2010, even as the country's GDP grew at a robust 5.1 percent per year over the same period. This decoupling of economic growth from transport emissions growth represents a positive trend, though the sector's dominant share of total emissions underscores the need for continued vigilance and policy action.

The modal composition of transport emissions in the Solomon Islands reveals a distinctive pattern shaped by the country's island geography and maritime economy. By 2022, domestic navigation accounted for 73 percent of transport PM 2.5 emissions, with road transport contributing 27 percent, domestic aviation 1 percent, and rail contributing negligible amounts. This distribution has shifted markedly since 2010, when road transport accounted for 45 percent and domestic navigation for 53 percent of transport PM 2.5 emissions. The growing dominance of maritime emissions reflects the critical role of inter-island shipping in connecting the country's dispersed population and supporting economic activity. Within the road sector, non-exhaust emissions from resuspended dust, brake wear, and tire wear have become increasingly significant, contributing 33 percent of road sector emissions by 2022, up from 17 percent in 2010. This trend highlights the need for comprehensive approaches to air quality management that address both tailpipe and non-tailpipe sources of emissions.

The emissions profile extends beyond particulate matter to encompass a range of air pollutants with varying health and environmental impacts. Nitrogen oxide (NOx) emissions from the transport sector increased by 1.9 percent annually between 2000 and 2010 but declined by 4.8 percent annually between 2010 and 2022, accounting for 36 percent of total NOx emissions by 2022. Road transport contributed 62 percent of transport NOx emissions in 2022, down from 70 percent in 2010, while domestic navigation's share increased from 21 percent to 34 percent over the same period. Domestic aviation accounted for 4 percent of transport NOx emissions. Sulfur oxide (SOx) emissions from transport declined steadily, falling by 2.5 percent annually between 2000 and 2010 and by 1.4 percent between 2010 and 2022, with the sector contributing 9 percent of total SOx emissions by 2022. Domestic navigation dominated transport SOx emissions at 98 percent, with domestic aviation contributing 2 percent and road transport virtually eliminated as a source following the shift away from high-sulfur fuels.

The Solomon Islands' transport sector also generates significant emissions of methane (CH4), non-methane volatile organic compounds (NMVOC), and black carbon (BC), each with distinct climate and health implications. CH4 emissions from transport grew by 2.4 percent annually between 2000 and 2010 before declining by 3.5 percent per year between 2010 and 2022, with 91 percent originating from the road sector by 2022. NMVOC emissions followed a similar trajectory, growing by 3.9 percent annually in the first period and declining by 2.0 percent in the second, with the road sector accounting for 68 percent of transport NMVOC emissions by 2022. BC emissions, which have particularly severe health impacts due to their fine particle size and composition, grew by 2.0 percent annually between 2000 and 2010 but declined sharply by 5.3 percent per year between 2010 and 2022. By 2022, domestic shipping accounted for 59 percent of transport BC emissions, with road transport contributing 41 percent and domestic aviation 1 percent. The shift in BC emissions away from road transport—which declined from 65 percent in 2010 to 41 percent by 2022—parallels the trend observed for PM 2.5 emissions and reflects improvements in vehicle technology and fuel quality alongside the growing relative importance of maritime transport.

Energy consumption patterns in the transport sector reveal the country's near-complete dependence on fossil fuels and the limited progress toward cleaner energy alternatives. In 2023, the road sector accounted for 87 percent of total transport energy consumption, with domestic navigation contributing 12 percent and domestic aviation 2 percent. Rail transport, which is essentially non-existent in the Solomon Islands, contributed nothing to energy consumption. Oil products comprised 100 percent of transport sector energy consumption in 2023, unchanged from 2010 and 2015, indicating no diversification of the energy mix. Biofuels and electricity each constituted 0 percent of transport energy consumption by 2023, highlighting the absence of alternative fuel adoption despite their potential to reduce both air pollution and greenhouse gas emissions. This fossil fuel dependence carries significant external costs beyond direct health impacts: 14 percent of the external costs associated with fossil fuel subsidies in the Solomon Islands takes the form of additional local air pollution, compounding the economic burden on society.

The fiscal implications of the country's transport energy system present both challenges and opportunities for policy reform. Fuel tax revenues comprise approximately 1 percent of total government revenue in the Solomon Islands, providing a modest but meaningful source of public financing. However, this revenue stream faces structural decline as global trends toward transport electrification progress, creating fiscal pressure that may necessitate alternative revenue mechanisms in the future. The current low level of electric vehicle (EV) adoption underscores the early stage of this transition: between 2017 and 2024, the value of EV imports reached only 575,000 USD, representing less than 1 percent of total road vehicle imports by 2024. The composition of EV imports included 38 percent light-duty vehicles, 61 percent goods vehicles and buses, and 1 percent two-wheelers, suggesting initial uptake in commercial rather than private passenger segments.

The Solomon Islands' readiness to accelerate the transition to cleaner transport technologies is constrained across multiple dimensions. The UNEP E-mobility Readiness Index assigns the country a score of 61 out of 100, with component scores of 7 in technology and market, 15 in policy, 19 in energy, and 20 in financial instruments. These scores indicate substantial gaps in the enabling environment required for large-scale adoption of electric mobility, including limited market development, weak policy frameworks, inadequate energy infrastructure, and insufficient financial mechanisms to support consumer adoption and private sector investment. Addressing these barriers will require coordinated policy interventions spanning regulatory reform, infrastructure development, capacity building, and innovative financing arrangements tailored to the country's unique geographic and economic circumstances.

Motorization trends add further complexity to the air quality management challenge. Vehicle ownership in the Solomon Islands reached 387 vehicles per thousand population in 2024, up from 325 in 2000, exceeding the Asia-Pacific average of 317 vehicles per thousand population. This relatively high motorization rate, combined with the country's small population and dispersed settlement patterns, creates unique challenges for implementing traditional urban transport solutions such as mass transit systems. Access to public transport remains severely limited: among the country's single urban agglomeration, 8 out of 10 residents do not have convenient access to public transport, forcing reliance on private vehicles and contributing to both air pollution and traffic congestion. Improving urban mobility while reducing emissions will require innovative approaches that account for the Solomon Islands' specific geographic, demographic, and economic context, including strategies tailored to small island states with limited fiscal and institutional capacity.

EV in freight

EV in public transport

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