The California Air Resources Board has adopted a regulation to reduce diesel emissions from the state’s estimated 180,000 vehicles used in construction, mining, airport ground support and other industries.

According to ARB, the new regulation “will dramatically reduce emissions by installation of diesel soot filters and encouraging the replacement of older, dirtier engines with newer emission controlled models. By 2020, diesel particulate matter will be reduced by 74 percent and smog forming oxides of nitrogen by 32 percent, compared to what emissions would be without the regulation.”

The new rule also includes a provision allowing areas that are currently unable to achieve clean air standards set by the U.S. EPA for particulate matter to opt in to stricter regional requirements if incentive funds are made available. The air districts that could take advantage of this provision are the South Coast Air Quality Management District and the San Joaquin Valley Air Pollution Control District; both are considered “non-attainment areas” for particulate matter. Depending on the amount of incentive money made available, these provisions could as much as a double the NOx emissions benefits in these districts, setting them on a faster track to meeting their clean air goals.

The requirements and deadlines vary depending on fleet size. For small fleets, which include small businesses or municipalities with a combined horsepower of 2500 or less, implementation does not begin until 2015. Medium fleets, with 2501 to 5000 horsepower, have until 2013, while large fleets, with over 5000 horsepower, must begin complying in 2010. Affected vehicles include bulldozers, loaders, backhoes and forklifts, as well as many other self-propelled off-road diesel vehicles.