EPA strengthens smog-forming emissions rules for heavy trucks

Washington — The U.S. Environmental Protection Agency implemented new, more stringent limits on smog-producing emissions from heavy-duty trucks Tuesday.

It is the first time tailpipe standards have been tightened for the heaviest class of vehicles — such as semi-trucks, garbage trucks and tractor-trailers — in more than 20 years and are more than 80% stronger than current standards.

The new standards, which will go into effect for Model Year 2027 vehicles, are expected to reduce nitrogen oxide output by 48% by 2045. They are also expected to reduce carbon monoxide by 18%, particulate matter by 8% and volatile organic compounds by 23% in the same timeframe.

Heavy-duty vehicles are one of the largest contributors of transportation-related nitrogen oxide emissions in the U.S. Without the new rules, EPA estimated they would make up 90% of on-road nitrogen oxide emissions by 2045.

Nitrogen oxide is a pollutant that can cause heart disease, asthma and other lung diseases. People who live close to highways are most affected by nitrogen oxide pollution, which includes an estimated 72 million people who are disproportionately low-income or people of color, said EPA administrator Michael Regan.

“This rule will result in widespread air quality improvements across the U.S., especially in communities near major roadways that are overburdened by air pollution,” he said.

However, the new rule doesn’t go as far as the one the agency proposed in March, which would have reduced nitrogen oxide emissions by up to 60% by 2045, frustrating some environmental groups.

“These standards fall short, and the agency missed a critical opportunity to slash soot and smog and accelerate the shift to the cleanest vehicles,” said Britt Carmon, federal clean vehicles advocate at the Natural Resources Defense Council, urging EPA to put the next round of standards in place as quickly as possible.