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 and contributing to the goals of the Coalition.


Location of activities

  • Global
  • Asia and the Pacific
    • Thailand

Description of activities

Workstream | Heavy-Duty Vehicles
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 | Heavy-Duty Vehicles
The overall objective of this workstream is to address the area of ports and marine vessels where there is significant need and opportunity for improved climate and health benefits through major...
Workstream | Heavy-Duty Vehicles
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 | Heavy-Duty Vehicles
The Global Strategy to Introduce Low Sulfur Fuels and Cleaner Diesel Vehicles – the first global plan to reduce small particulate and black carbon emissions from cars, buses and trucks by over 90% by...
The Global Sulfur Strategy
Activity | Finance, Heavy-Duty Vehicles, Household Energy
Black carbon is a major contributor to near-term climate change and a dangerous air pollutant. It increases glacier melting, harms public health, disrupts weather patterns and reduces food security...


  • Global Strategy to Introduce Low Sulphur Fuels and Clean Diesel Vehicles sets first global timeline for cleaner fuels: all countries adopt all countries to 50 ppm low sulfur fuels by 2025, and most countries go to ultra-low (10 ppm) sulfur in fuels by 2030.
  • Strategy launched at COP 21 in Paris, the first global plan to reduce black carbon emissions from cars, trucks and buses by over 90%.
  • 38 countries endorse the strategy at the Coalition's 2016 High Level Assembly
  • If fully implemented by 2050, the strategy would result in 500,000 avoided deaths per year and reduced cumulative emissions of diesel black carbon by an estimated 7.1 million metric tonnes.

Current milestones:

  • 30+ countries including East, West and Southern Africa, Barbados, Chile, China, Colombia, Costa Rica, Indonesia, Mexico, Panama, Paraguay, Peru, Uruguay introduce strict low sulfur diesel and vehicle emissions standards
  • 20 cities worldwide transitioning to soot-free urban bus fleets
  • 57 countries, companies and organisations support the Global Green Freight Action Plan
  • 4 global bus manufacturers - BYD, Cummins, Scania, and Volvo - commit to providing 20 megacities with soot-free bus technology
  • Global marine black carbon emissions inventories and baseline air emissions inventories produced for major ports in Indonesia, Ghana, Bangladesh, Kenya and Chile
  • 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
  • Foundations for green freight programs developed in Brazil, Mexico and Vietnam, and under development in China

Initiative contacts

Denise San Valentin,
Initiatives Coordinator/Programme Manager
denise.sanvalentin [at] un.org

Partners & Actors

Lead Partner: A Coalition partner with an active role in coordinating, monitoring and guiding the work of an initiative.

Implementer: A Coalition partner or actor receiving Coalition funds to implement an activity or initiative.

Partners (42)


Actors (35)


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.


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