American firms with fleets of diesel engines can apply for funding from a $9 million (£5.8m) pot to begin new projects to reduce emissions.
The US Environmental Protection Agency (EPA) made the announcement as part of the National Clean Diesel Funding Assistance (DERA) programme, which aims to improve air quality by reducing pollution and saving fuel. According to the EPA, clean diesel funding generates up to $13 (£8.4) of public health benefit for every $1 (£0.64) spent on diesel projects.
Projects include those that cut air pollution from older school buses, transit buses, heavy-duty diesel trucks, marine engines and other diesel engines.
Between 2008-2010, more than 50,000 vehicles and equipment in a variety of industries have been retrofitted or replaced and the projects helped reduce emissions by at least 203,900 tons of nitrogen oxide and 12,500 tons of particulate matter emissions over the lifetime of the engines.
The EPA has awarded more than 500 grants across the US since the first year of the DERA programme in 2008.