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The Kenworth medium duty battery-electric truck from MHC Kenworth – Greeley, left, and the International electric MV Series truck from McCandless Truck Center, loom large on the showroom floor at the opening day of the Denver Auto Show at the Colorado Convention Center April 12 in Denver. (Kathryn Scott, Special to The Colorado Sun)

The Air Quality Control Commission on Friday unanimously approved a California-style mandate for medium- and heavy-duty truck manufacturers to sell clean electric models in Colorado beginning in 2027, and to cut nitrogen oxide emissions from new diesel trucks by 90% from current standards. 

The vote is one of the strongest efforts so far to cut greenhouse gas and ozone-causing emissions from the stubborn transportation sector, which has lagged behind electric power plant conversions to renewable generating sources in the overall battle to slow climate change. 

Colorado joins a handful of other states copying EPA-approved regulations from California’s so-called Advanced Clean Trucks strategy. Diesel engines contribute even more nitrogen oxide, or NOx, pollutants to the air than gasoline engines, and often run all day and all night in the trucking industry. The new rules, taking effect for 2027 model year trucks that will start showing up at dealers in 2026, require the percentage of clean electric trucks sold by manufacturers to ratchet up each year. 

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While medium- and heavy-duty trucks are just 10% of the vehicles on U.S. roads, they put out 25% of the greenhouse gas emissions from transportation, according to the Union of Concerned Scientists

Trucks powered by hydrogen fuel cells will also qualify, though they are years from mass production and adoption. The new Colorado rules also drastically reduce the amount of NOx allowed from new diesel truck engines, while also extending warranties so that trucking companies can get factory repairs for emissions problems for far longer. 

The trucking industry objected to the AQCC adopting the rules, but had largely accepted their fate with the entire Polis administration lined up behind the mandates. They say they will now turn their attention to seeking financial incentives for companies to buy the expensive new electric models, and to build out the necessary network of heavy-duty, rapid chargers at fleet lots and along trucking corridors. 

Colorado’s Department of Public Health and Environment, which provides the staff for the volunteer air quality commissioners, said there are incentives of up to $40,000 available for buying a clean electric truck, whose prices run into the hundreds of thousands of dollars. 

Truckers need convincing with a wider array of new products that electric hauling can deliver the same payload despite heavy battery packs, according to the Colorado Motor Carriers Association. Companies also worry battery performance will be worse than in California when tested by Colorado’s mountain climbs and cold winters. 

Support for the clean trucks rules was overwhelming, however, in months of informational meetings and three days of deliberations at the AQCC. Clean air advocates note Colorado is behind on its greenhouse gas reduction goals, and has also been declared in “severe” violation of the EPA’s health limits for ozone in the nine-county north Front Range metro corridor. 

Environmental groups and local elected officials frustrated by ozone violations say the clean trucks rules are an overdue companion to clean passenger cars mandates passed years ago by the AQCC. Under the clean cars rules, Colorado passenger car and light truck dealers must sell an increasing percentage of electric or other ultra-low emissions engines into the 2030s. Consumer demand for cleaner vehicles has easily surpassed those percentages in Colorado. 

The clean trucks rule also makes a big step toward fulfilling federal and state laws requiring clean air decisions with an eye toward environmental justice for disproportionately impacted communities, said commission member Dr. Tony Gerber, a pulmonologist. For lower-income and minority neighbors to metro Denver’s tangle of interstates and warehouses, “this is a huge rule,” Gerber said. 

“Today’s vote is an important and powerful step towards addressing climate change, environmental justice, and public health,” said Eagle County Commissioner Matt Scherr, in a release from Colorado Communities for Climate Action, where Scherr is president. “These rules will significantly lower emissions from the transportation sector, the largest source of climate pollution in our state and a significant source of dangerous air pollution as well.”


Colorado officials are counting on the clean trucks and clean cars rules to do most of their work in reducing both ozone emissions and greenhouse gases in the next few years. Efforts to mandate cuts to consumer and work-related driving by individuals has been met with fierce opposition, and one significant plan was abandoned by the health department last year. 

The air quality commission plans to strengthen the passenger car regulations in coming months by passing a set of rules called Clean Cars 2, again copying California’s new rules. California in August announced it would ban all sales of new gas-fueled vehicles by 2035, accelerating the switch to electric motors laid out in the first set of car rules. 

Michael Booth

Michael Booth is a Colorado Sun reporter covering health, health policy and the environment. Email: Twitter: @MBoothDenver