The transport sector is a major contributor to ambient fine particles in major cities, and emits some 19% of global black carbon. Recent research has identified diesel vehicles and engines as one of the most attractive sectors for black carbon mitigation. Fine particles and black carbon from diesel vehicles and engines can be virtually eliminated through technologies that are present on half of new heavy-duty vehicles sold today.

The Coaltion's Heavy-Duty Diesel Vehicles and Engines Initiative works to catalyse major reductions in black carbon through adoption of clean fuel and vehicle regulations and supporting policies. Efforts focus on diesel engines in all economic sectors.

Top facts

The transportation sector is a major contributor to black carbon emissions and was responsible for 19% of global black carbon emissions in 2000, contributing to 3.2 million deaths per year.
Global adoption of Euro VI standards could avoid 300 - 700 thousand premature deaths in 2030 by reducing particulates and co-pollutants emitted by on and off-road vehicles.
The CCAC Soot-Free Urban Bus Fleets project works towards soot-free engine technologies in 20 major cities, home to a combined 234 million people, in order to prevent 3,700 early deaths and up to 6.6 MMT CO2e by 2030.

Fact sheets


The Initiative’s objective is to virtually eliminate fine particle and black carbon emissions from new and existing heavy-duty diesel vehicles and engines through the introduction of low sulfur fuels and vehicle emission standards. Roughly half of new and existing heavy-duty diesel vehicles are currently subject to world-class emission standards with diesel particle filters and the aim it so ensure that the remaining unregulated or inadequately regulated half of global diesel fleet will achieve the same. Our target is to reach 10 ppm sulfur in fuels by 2025 globally, while at the same time also supporting the introduction of vehicles emissions standards, contributing to the overall goal of the CCAC.


Description of activities

Workstream | Diesel
Bus fleets provide widely affordable low carbon transportation around the world. But urban buses are powered predominantly by diesel engines, accounting for approximately 25% of the black carbon...
Workstream | Diesel
Ports are a significant source of air pollution in coastal areas, with serious impacts on the environment and human health. Roughly three quarters of the world’s large cities are located on coasts,...
Workstream | Diesel
The freight sector— which includes trucks, trains, marine vessels, airplanes, and other modes — provides a vital service delivering foods, goods, and resources. But, the movement of freight also...
Workstream | Diesel
The Global Strategy to Introduce Low Sulfur Fuels and Cleaner Diesel Vehicles is the first global roadmap to reduce small particulate and black carbon emissions from the global on-road diesel fleet...
The Global Sulfur Strategy


At COP 21 in Paris, the Diesel initiative launched the Coalition's 'Global Strategy to Introduce Low Sulphur Fuels and Clean Diesel Vehicles', the first global plan to reduce black carbon emissions from the global on-road diesel fleet by over 90%. At the Coalition's 2016 High Level Assembly 38 countries endorsed the strategy. The strategy sets a global timeline: most countries adopt low sulphur diesel by 2020, and countries to 50 ppm by 2025, and most countries go to ultra-low (10 ppm) sulfur in fuels by 2030.

If fully implemented by 2050, it would result in 500,000 avoided deaths per year and reduce cumulative emissions of diesel black carbon by an estimated 7.1 million metric tonnes. The initiative is now working with a number of countries toward these goals.

5-year milestones:


  • 35 countries and East, West and Southern Africa supported to introduce strict low sulfur diesel and vehicle emissions standards
  • 57 countries, companies and organisations support the Global Green Freight Action Plan
  • Global marine black carbon emissions inventories and baseline air emissions inventories produced for major ports in Indonesia, Ghana, Bangladesh, Kenya and Chile
  • 20 cities worldwide transitioning to soot-free urban bus fleets
  • Foundations for green freight programs developed in Brazil, Mexico and Vietnam, and under development in China
  • 4 global bus manufacturers - BYD, Cummins, Scania, and Volvo - commit to providing 20 megacities with soot-free bus technology
  • Development and adoption of more stringent fuel and/or vehicle emission standards at the regional and national levels, including in Barbados, China, Colombia, Costa Rica, Indonesia, Mexico, Panama, Paraguay, Uruguay, East Africa, West  Africa and Southern Africa
  • Nigeria, Togo, Benin, Cote d'Ivoire, and Ghana adopted low sulfur diesel fuel standards; Mozambique, Malawi and Zimbabwe switched to low sulfur diesel fuels and Nigeria agreed to import low-sulfur diesel fuels (50 ppm) in 2017
  • Indonesia's state-owned Pertamina signed contracts to upgrade 5 of its refineries to produce 50 ppm fuels (down from 500 ppm) and the government adopted Euro4/IV equivalent vehicle standards nationwide for implementation in 2018
  • The International Marine Organisation (IMO) reaffirmed its marine global 0.5% sulfur limit for 2020, and restarted work on a potential Heavy Fuel Oil (HFO) ban under the Polar Code. In China, ports in the Bo Sea, Yangtze River Delta, and Pearl River Delta began early implementation of the 0.5% sulfur limits

Initiative contacts

Denise Sioson,
Diesel & HFC Initiative Coordinator
Denise.Sioson [at] un.org

Partners & Actors


How does PM and black carbon from the transport sector affect human health?

Fine particles penetrate deep into the lungs. A recent study of leading public health risks ranked ambient fine particle pollution ninth among all risk factors in 2010, contributing to 3.7 million deaths in 2012. Black carbon is the second largest contributor to human-induced climate warming to-date, after carbon dioxide. All major OECD economies have dramatically reduced fine PM and BC emissions from heavy-duty diesel vehicles through a combination ultra-low sulfur diesel fuel and diesel emission control technologies; there is up to a 99 per cent removal efficiency with diesel particulate filters.

What is desulfurization in the transport sector? Why is it important?

Desulfurization refers to the gradual move to low sulfur fuels. Most developed countries have now moved to fuels with a sulfur content of 50 parts per million or even 15 or 10 parts per million (ppm). Reducing fuel sulfur levels is a vital precondition for reducing the health impacts associated with transportation. Fuel sulfur directly increases production of fine particulate matter (PM2.5) in vehicle exhaust. PM2.5 is a dangerous pollutant associated with heart disease, lung cancer, and a range of other harmful health effects. Low sulfur fuels are necessary for cleaner engines (for example high compression diesel engines) and high fuel sulfur levels also interfere with the performance of vehicle emissions control equipment designed to remove small particulates and other pollutants from the exhaust stream (for example particulate filters and catalysts).

What is green freight? Why is it important?

Green freight refers to the efforts of the freight sector to help reduce greenhouse gas emissions and air pollutants and improve fuel efficiency across the global supply chain while maintaining competitiveness and economic growth. By reducing the amount of energy (i.e., fuel use) associated with freight transport through a range of measures, businesses can reduce costs and become more competitive. These efficiency measures invariably lead to emissions savings that result in broader benefits for society and the environment. Freight movement is largely driven by diesel-powered cargo vessels, trucks, and trains. While diesels are the workhorses of the transport sector and relatively energy efficient (as compared to gasoline vehicles or jet aircrafts), their combined contribution to transportation-related climate warming greenhouse gases and other short-lived climate pollutants, particularly black carbon, is significant.

What does 'soot-free' transport entail?

Soot-free engine technologies are those that achieve at least a 99% reduction in tailpipe black carbon emissions compared to uncontrolled diesel exhaust. These technologies include any diesel or alternative fuel engines certified to Euro VI or US 2010 emission levels.

As an example, soot-free buses can be powered by a wide range of fuels including fossil diesel or compressed natural gas (CNG), biogas, or other liquid biofuels, and electric drive engines including hybrid drive, fuel cell, and battery electric drivetrains. A soot-free bus – be it diesel, natural gas or electric – will emit 99% less tailpipe PM2.5 and 85% less black carbon compared to a diesel bus without any emission controls.


2017 | Reports, Case Studies & Assessments
, China Automotive Technology and Research Center Beijing Operations (CATARC Beijing)

Supported by the International Council on Clean Transportation’s (ICCT) experience and freight assessment methodologies, the China Automotive Technology and Research Center Beijing Operations (...

The aim of the Heavy-Duty Diesel Initiative of the Climate and Clean Air Coalition is to virtually eliminate black carbon and fine particulate emissions from the on-road vehicle fleet by 2030. The...

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