Publications·March 18, 2025·CCAC – Climate and Clean Air Coalition
The UNEP report “Accelerating the Global Shift to a Cleaner On-Road Diesel Fleet” (2025) provides a comprehensive global update on the transition toward low-sulfur fuels and cleaner diesel vehicle technologies. Produced in partnership with the Climate and Clean Air Coalition (CCAC) and the International Council on Clean Transportation (ICCT), the report tracks policy implementation, fuel quality, and vehicle emission standards in more than 150 countries. It identifies the transport sector as a leading source of fine particulate matter (PM2.5), nitrogen oxides (NOx), and black carbon, which contribute to both premature deaths and climate warming. The analysis highlights Asia as a region of rapid progress yet significant disparity, with strong policy leadership in East and South Asia but continued challenges in fuel quality and inspection systems across lower-income economies. The Asia and Pacific chapter documents that 20 countries have now adopted fuels with sulfur content of 50 parts per million (ppm) or lower, and 16 countries have implemented Euro 4/IV or stricter vehicle emission standards. Subregional profiles show that Southeast Asian nations such as Thailand, Viet Nam, Malaysia, Singapore, and Brunei Darussalam have already achieved Euro V or VI equivalency, while Indonesia and the Philippines are targeting full compliance by 2030. South Asian progress is anchored by India’s nationwide adoption of Bharat Stage VI (Euro VI-equivalent) standards in 2020, alongside regional spillover benefits to Nepal and Bangladesh through cross-border fuel trade. The report also details ongoing refinery modernization in Pakistan and Bangladesh and highlights the need for enforcement capacity and vehicle inspection reform. In East Asia, China and the Republic of Korea maintain stringent fuel and vehicle standards, while Mongolia has adopted a 10 ppm standard but faces implementation challenges. The Pacific region shows emerging leadership in small island developing states such as Fiji and Vanuatu, both of which now use ultra-low-sulfur diesel (10–50 ppm) and Euro IV–V compliant vehicles. UNEP’s analysis identifies key policy instruments enabling progress, including national clean air action plans, regional roadmaps, and intergovernmental frameworks such as the ASEAN White Paper on Soot-Free Heavy-Duty Vehicles and the SACEP Framework on Clean Fuels and Vehicles. The report emphasizes the public health and climate co-benefits of ultra-low-sulfur fuel adoption, estimating that full global transition could prevent hundreds of thousands of premature deaths annually while reducing black carbon emissions by up to 90%. It calls for accelerated implementation of cleaner fleets, strengthened regional cooperation, and mobilization of finance for refinery upgrades and vehicle fleet modernization. For Asia, UNEP and CCAC recommend harmonizing fuel and vehicle standards across ASEAN and South Asia by 2030, promoting zero-emission heavy-duty vehicles, and aligning transport decarbonization efforts with national air quality and climate targets. The report concludes that the shift to a cleaner diesel fleet is a cornerstone of sustainable urban development and a critical pathway for reducing both air pollution and climate impacts in the transport sector across Asia and the Pacific.
This report provides an updated global strategy to accelerate the transition to cleaner fuels and vehicles, focusing on reducing sulfur levels in fuels and adopting advanced vehicle emission standards. It emphasizes the urgent need for harmonized global action to mitigate air pollution, improve public health, and reduce climate impacts from the transport sector. The strategy targets low- and middle-income countries (LMICs), where high-sulfur fuels and outdated vehicle fleets remain prevalent.
This report provides an updated global strategy to accelerate the transition to cleaner fuels and vehicles, focusing on reducing sulfur levels in fuels and adopting advanced vehicle emission standards. It emphasizes the urgent need for harmonized global action to mitigate air pollution, improve public health, and reduce climate impacts from the transport sector. The strategy targets low- and middle-income countries (LMICs), where high-sulfur fuels and outdated vehicle fleets remain prevalent.
Purpose and Objectives
The report outlines a roadmap for achieving:
Fuel Quality Improvements: Transition to low-sulfur fuels (50 ppm or below), with an ultimate goal of ultra-low sulfur fuels (10 ppm).
Vehicle Emission Standards: Adoption of Euro 4/IV standards as a minimum, progressing toward Euro 6/VI.
Integrated Approach: Aligning fuel quality and vehicle standards to maximize air quality and climate benefits.
The strategy aims to reduce particulate matter (PM2.5), black carbon, and CO₂ emissions, contributing to global climate targets and improved urban air quality.
Why Cleaner Fuels and Vehicles Matter
Health Impact: Air pollution causes 8.8 million premature deaths annually; on-road vehicles are a major contributor in LMICs.
Climate Impact: Transport accounts for ~25% of energy-related greenhouse gas emissions, projected to rise to one-third by 2050.
Technical Link: Advanced emission control technologies (e.g., diesel particulate filters) require low-sulfur fuels to function effectively.
Global Disparity: 78 countries still use fuels with sulfur >50 ppm; 92 countries lack Euro 4/IV standards.
Progress to Date
In 2006, only 40 countries had low-sulfur fuel standards; by 2025, 115 countries have adopted ≤50 ppm sulfur diesel.
101 countries have Euro 4/IV or better vehicle standards.
UNEP’s Partnership for Clean Fuels and Vehicles (PCFV) and CCAC have driven progress through technical support and regional harmonization efforts.
Despite gains, significant gaps remain in Africa, Asia-Pacific, Latin America, and the Middle East.
Regional Analysis
Africa
Achievements: East Africa (EAC) countries implemented 50 ppm fuel standards and Euro IV vehicle standards; Morocco adopted Euro VI.
Challenges: Central Africa lags due to old refineries and lack of vehicle standards; West Africa struggles with ECOWAS Directive implementation.
Opportunities: Harmonization through African Union and ARSO; electric bus programs in Kenya, Uganda, and Rwanda.
Asia & Pacific
ASEAN: Most countries at Euro IV; Thailand and Vietnam moving to Euro V/VI; Indonesia delayed to 2028 for 50 ppm fuels.
South Asia: India leads with Bharat Stage VI; Bangladesh and Maldives need support for full implementation.
Pacific Islands: Limited progress; reliance on fuel imports and used vehicles from Japan and Korea.
Latin America & Caribbean
Leaders: Mexico, Chile, Costa Rica advanced in fuel and vehicle standards.
Lagging Countries: Many Caribbean nations still at 500 ppm sulfur; weak enforcement of vehicle standards.
Trends: Growing imports of used EVs and hybrids, but infrastructure gaps persist.
Middle East & West Asia
Lebanon and Oman have low-sulfur fuels but lack Euro IV standards.
Kyrgyzstan and Tajikistan progressing toward Euro 4/IV and low-sulfur fuels.
Eastern Europe & Caucasus
Most countries aligned with Euro V/VI and low-sulfur fuels due to EU influence.
Focus shifting to electric mobility and ZEV adoption.
Strategic Considerations
Fuel-Vehicle Systems Approach: Synchronize fuel and vehicle standards for maximum impact.
Air Quality & Climate Benefits: Position transition as a key contributor to national environmental goals.
Bridge to Zero-Emission Vehicles: Euro IV+ standards as a stepping stone to EV adoption.
Regional Harmonization: Reduce fragmentation and enforcement gaps.
Leverage Importing Markets: Drive global desulfurization through demand for cleaner fuels.
Regulate Used Vehicle Exports: Prevent dumping of high-emission vehicles in LMICs.
Accelerate HDV Transition: Promote soot-free buses and green freight corridors.
Barriers
Economic constraints for refinery upgrades.
Regulatory gaps and weak enforcement.
Infrastructure limitations for cleaner fuels and vehicles.
Political resistance and market dynamics favoring older vehicles.
Opportunities
Health and climate benefits.
Technology advancement and economic growth.
International support through UNEP, CCAC, and development banks.
Priority Actions
Support countries close to implementing 50 ppm fuels and Euro IV standards.
Enhance monitoring and compliance mechanisms.
Promote electric buses and green freight corridors.
Strengthen regional cooperation frameworks (e.g., ECOWAS, ASEAN, SICA, CARICOM).
Key Words
Low-sulfur fuels, Euro 4/IV standards, Euro 6/VI standards, vehicle emissions, black carbon, PM2.5, air quality, climate mitigation, heavy-duty vehicles, green freight, electric buses, regional harmonization, LMICs, refinery upgrades, used vehicle imports, subregional strategies, UNEP, CCAC, PCFV, transport sector, zero-emission vehicles, policy frameworks, compliance monitoring.