The California Air Resources Board on Nov. 17 approved amendments to the In-Use Off-Road Diesel-Fueled Fleets Regulation (Off-Road Regulation) aimed at further reducing emissions from the off-road sector. The amendments will require fleets to phase-out use of the oldest and highest polluting off-road diesel vehicles in California; prohibit the addition of high-emitting vehicles to a fleet; and require the use of R99 or R100 renewable diesel in off-road diesel vehicles.

Off-road vehicles subject to the amendments are used in construction, mining, industrial operations, and other industries. The amendments phase-in starting in 2024 through the end of 2036 and include changes to enhance enforceability and encourage the adoption of zero-emission technologies.

“The oldest off-road diesel-fueled vehicles with no emission controls are 80 times as polluting as a similar sized off-road vehicle purchased today,” said CARB Chair Liane Randolph. “It’s imperative for public health, especially for the hardest hit communities suffering from persistent pollution, that we reduce emissions across every category of the transportation sector as we work towards cleaner air.”

The amendments are expected to yield $5.7 billion in health benefits, prevent more than 570 air-quality related deaths and nearly 200 hospitalizations and emergency room visits from 2023 to 2038. The estimated cost of the program is $1.9 billion.

Today’s amendments will further reduce harmful air pollutants from over 150,000 in-use off-road diesel vehicles that operate in California. The off-road sector (excluding locomotives, aircraft, waterborne vessels, portable equipment and agriculture) comprises about 14 percent of the total statewide emissions of nitrous oxide (NOx). That constitutes the second largest mobile source of NOx in California, only exceeded by trucks on roads and highways (“on-road trucks”).

From 2024 through 2038, the current amendments will generate an additional reduction above and beyond the current regulation of approximately 31,087 tons of NOx and 2,717 tons of fine particle pollution (known as PM2.5). About half of those additional reductions are expected to be realized within the first five years of implementation.

These polluting emission reductions are driven by the 2022 State Strategy for the State Implementation Plan which requires a reduction of NOx emissions by 4 tons per day by 2037 in the off-road diesel sector. In addition, the 2022 State Strategy specifies the need to reduce diesel PM2.5 at a statewide level to reduce the health risk throughout California, especially in communities that experience disproportionate burdens from exposure to toxic air contaminants.

CARB developed the amendments based on input from a robust public process that included public meetings, workshops, stakeholder input and site visits. As a result of the input received, for ultra-small fleets (those with total combined equipment horsepower of 500 or less), CARB incorporated a compliance extension for the phase-out of some older vehicles. CARB also developed a compliance exemption for fleets that are unable to obtain R99 or R100 renewable diesel for their fleet.  

CARB initially adopted the Off-Road Regulation in 2007 and approved amendments in 2009 and 2010.