Diesel exhaust is a significant component of greenhouse gases, containing a complex mixture of chemicals and fine particles of soot. Human exposure to this mixture has been shown to exacerbate asthmatic symptoms or even cause asthma, and many of the chemicals contained in diesel exhaust have been identified as known carcinogens. It’s responsible for more than 20% of the nation’s nitrogen oxide emissions and 15% of all particulate matter. An old diesel engine can emit almost 8 tons of pollution every year.

One solution is the use of Ultra-Low Sulphur Diesel (ULSD) fuel — a cleaner version of diesel fuel that eliminates almost 97% of the pollutants, especially the sulphur that creates the noxious black smoke you sometimes see pouring from diesel truck exhaust pipes. Standard diesel fuel has up to 500 parts per million (ppm) of sulphur; ULSD has only 15 ppm.

There are also physical devices which can be retrofitted to existing diesel engines to substantially reduce their emissions. Closed Crankcase Ventilators (CCVs) reduce particulate matter almost to ambient air levels. Diesel oxidation catalysts can reduce particulate matter emissions by as much as 40%, and carbon dioxide emissions by as much as 90%. A diesel particulate filter can reduce both emissions and carbon monoxide by up to 90%. Used in combination with Ultra-Low Sulphur Fuels, these devices can reduce the pollution from diesel exhaust to negligible levels.

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Both the EPA and many state agencies have programs to financially assist municipalities in retrofitting their vehicles and construction equipment with pollution control devices.

Through the National Clean Diesel Campaign, EPA will award grants to assist its eligible partners in building diesel emission reduction programs across the country, improving air quality and protecting public health.

The Diesel Technology Forum is a leading information source on clean diesel and energy issues. On their extensive website you can find information about local initiatives available to help communities retrofit their diesel-powered vehicles.