Heavy-duty diesel engines and equipment are significant sources of black carbon, toxics, greenhouse gases and other harmful emissions. An estimated 19 percent of black carbon emissions in the world come from the transportation sector, with a relatively large share coming from diesel vehicles.
Most of the emissions from older diesel vehicles come in the form of particulate matter, 75 percent of which is typically black carbon. Black carbon has major effects both on human health and the climate, with a global warming potential second only to CO2. Particulate matter is among the top human health risk factors, resulting in millions of premature deaths worldwide every year.
Major sources of diesel emissions include road transport and non-road transport, such as construction and agricultural equipment, locomotives and marine vessels.