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 CCAC Heavy-Duty Diesel Vehicles and Engines Initiative (HDDI) 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.

                                                                     The Global Sulfur Strategy

                                                                                  Green Freight      

                                                           Reducing Black Carbon from ports     

                                                                            Soot-free Bus Fleets


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
Trade in goods and materials drives global economic growth and development, linking nations and markets through an increasingly interdependent supply chain. The Global Green Freight Project was...
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


2017 | Official Statements
Climate and Clean Air Coalition (CCAC)

This document presents results from the Climate & Clean Air Coalition’s Diesel Initiative reported between July 2016 and June 2017. These results were recorded using the Demonstrating...

Initiative contacts

Denise Sioson
Denise.Sioson [at] un.org

Pollutants (SLCPs)

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.

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Partners (23)



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.


2016 | Awareness Materials
The International Council on Clean Transportation and the United Nations Environment Programme

Diesel engines power the dominant share of goods movement, construction equipment, and public transport vehicles in the global economy. This strategy presents a roadmap to reduce small ...

2013 | Policies, Plans & Regulations
International Council on Clean Transportation (ICCT); Climate & Clean Air Coalition (CCAC)

There are many ways to improve air quality and reduce the climate-forcing impacts of vehicle use. Often overlooked in discussions of advanced vehicle technology and alternative fuels are the...

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