EPA rollback of climate rules could weaken California’s clean air authority and trigger legal battles over greenhouse gas protections.

The proposal strikes down all greenhouse gas standards for heavy-duty vehicles and heavy-duty engines, starting with EPA’s first greenhouse gas set in 2011 for medium-duty vehicles and heavy-duty vehicles and engines.

California's affordability crisis could lead to more relaxed emissions standards, according to a plan introduced by state Democrats.

Meanwhile, the EPA and the National Highway Traffic Safety Administration (NHTSA) will continue to test and label for Corporate Average Fuel Economy. Criteria pollutants are ozone, particulate matter, carbon monoxide, lead, sulfur dioxide, and nitrogen dioxide.

The Trump administration Tuesday announced plans to revoke the agency’s “endangerment finding” on greenhouse gases, setting the stage for the federal government to cease regulating climate-warming emissions.

The EPA’s plan to rescind greenhouse gas emissions rules is winning trucking industry support but sparking environmental backlash — and raising questions for early-adopter fleets that have already invested based on expected regulations.

The Trump administration has effectively eliminated two rules designed to promote cleaner cars. Now, as the EPA suggests not considering carbon dioxide to be pollution, the last is poised to fall.

Limiting trucks to no more than 65 mph nationally might have saved lives and fuel costs, but Trump regulators say it would have raised costs, stalled traffic.