Harmonizing Standards for Cleaner Transport Worldwide

by Climate and Clean Air Secretariat (CCAC) - 11 September, 2025

Vehicle emissions across Asia, Africa, and Latin America are projected to rise sharply, even as these same regions commit to net-zero targets over the next 30-40 years. Historically, motorization levels have been low in Africa, with Germany having around 500 cars per 1,000 people compared to just 30 in Kenya and 7 in Ethiopia. However, given demographic and economic trends, this is poised to change.

Transport is one of the only sectors where emissions are currently growing, largely driven by heavy-duty vehicles that, despite their smaller numbers, contribute a disproportionate amount of pollution. For instance, transport sector emissions have yet to plateau, now representing one-third of all emissions from the region, up from one-fourth at an earlier time. And in Latin America and the Carribean, fuel combustion in the transport sector is the main source of greenhouse gases emissions, representing 40% of the region’s total emissions.

The CCAC is committed to ensuring this growth is met with the adoption of practical and effective fuel and emission standards, preventing a surge in black carbon and CO₂ emissions.

Used Vehicles and Dirty Fuel

Vehicle emissions do not stop at borders, making the disparity in standards between neighboring countries a serious concern given the high volume of cross-border trade. For example, Kenya restricts the import of trucks older than eight years, while in Uganda the average imported truck is 34 years old—and because Ugandan trucks often spend more time driving in Kenya than at home, they contribute significantly to Kenya’s emissions. Similarly, in Vietnam limits used vehicle imports to those under five years old and requiring compliance with national emissions and roadworthiness standards. However, regulatory approaches to used vehicle imports remain inconsistent across the region, leaving countries like Cambodia vulnerable to the potential risks of high-emitting second-hand vehicles. This is particularly important given the popularity of imported used vehicles in places like Cambodia, where 96% of newly registered vehicles are purchased secondhand.

Even older cars can produce far fewer harmful emissions when cleaner fuels are used, but these fuels must be widely available to realize their benefits. The rollout of low-sulfur fuels is especially critical alongside the adoption of stricter vehicle emissions standards, since many advanced technologies—such as Euro VI vehicles—depend on them to function properly. If a country enforces Euro VI standards but drivers cross into a neighboring country without low-sulfur fuel availability, the vehicles’ emissions control systems can fail, undermining the technology, damaging the vehicles over time, and negating the intended environmental gains.

Taking a Sub-Regional Approach

To reduce cross-border pollution, the CCAC has supported the adoption of minimum vehicle emissions standards and low-sulfur fuel standards across Southern Africa and in Central America.

Africa

The CCAC has promoted the uptake of low-sulfur fuel standards, focusing on fuel-importing countries without refineries. In Southern Africa, for example, the CCAC worked with Mozambique—which supplies fuel to both Malawi and Zimbabwe—to help spread low-sulfur standards throughout the region. Targeted national follow-up has resulted in 11 out of 16 countries in the subregion now using low-sulfur fuels.

In December 2023, technical experts from 14 Southern African countries initiated the harmonization of low-sulfur fuel regulations and discussions on used vehicle restrictions. A sub-regional workshop in Madagascar at the end of July 2025 brought countries together to agree on regionally harmonized low-sulfur petrol and diesel standards.

The East Africa sub-region was the first outside the EU to adopt regionally harmonized low-sulfur fuel standards in 2015. These standards were revised in July 2025 to 10 parts per million (ppm) fuels. The sub-region also adopted harmonized vehicle emission standards at a minimum of EURO 4/IV in 2022.

The West Africa sub-region was also engaged to develop and adopt low-sulfur fuels at 50 ppm and stricter vehicle emissions standards at EURO 4/IV in 2020. The vehicle regulation also includes restrictions on used vehicles imported into the sub-region. However, the implementation of both the fuel and vehicle standards remains a challenge, with only 5 of the 15 countries implementing the fuel directive, and none has achieved EURO 4/IV import status.

Latin America

In Latin America, UNEP is working with the Central America Integration System—a political organization that gathers the Ministries of Transport, Environment, and Energy of Central American countries—to harmonize vehicle and fuel emissions regulations in the subregion for both passenger cars and heavy-duty vehicles across the new and used car markets. For four of the eight countries in the sub-region, the project has created baselines, which help countries have a comparison point to see the effect of and forecast future vehicle and fuel emissions standards. Using those baselines, UNEP has proposed a minimum vehicle emissions standard in Central America of Euro 6/VI. These standards will be discussed at the interministerial meeting in March 2026.

Southeast Asia

In Southeast Asia, there is a clear trend toward tightening vehicle and fuel emission standards. Thailand and Vietnam have already adopted Euro 5 fuel and vehicle standards, while Cambodia has announced plans to implement Euro 5 by 2027. This signals growing regional momentum toward cleaner transport, though approaches remain nationally driven and vary in enforcement capacity. Ongoing CCAC support pushing regional dialogues under ASEAN is paving a pathway for harmonized transition to electrification of HDVs in the region.

The Future is Electric

While there is a push to switch to electric vehicles (EVs)—with over 50% of modern vehicle sales being electric—this is not a realistic near-term solution for some of the regions the project focuses on. For instance, in West Africa, the vast majority of vehicles are imported secondhand, meaning EV adoption will likely not proliferate in the short term. In other contexts, such as in certain ASEAN countries, EVs have risen in popularity for passenger vehicles, but the cost for electric heavy-duty vehicles is still prohibitive without subsidies or support.

In Asia, CCAC’s support has enabled the planning for a future of electric vehicles in the heavy-duty vehicle sector. Technical assistance to governments in the region has helped create a roadmap to a sustainable EV market, essentially de-risking the changeover to electrification.