California officials celebrated the approval, but were also working to smooth out a last-minute spat with truck manufacturers that is holding up the approval of another tailpipe regulation.
EPA was set to approve a third waiver covering California’s “omnibus” rule, but held back amid the last-minute spat with the industry. The rule would reduce nitrogen oxide limits for new heavy-duty trucks by 90 percent compared to current standards by 2031.
The delay underscores the tenuousness of California’s attempts to limit emissions and transform heavily-polluting vehicles.
Under the Clean Air Act, California can seek waivers from EPA to enforce more stringent tailpipe regulations. Other states can choose to adopt California’s version of the rules, expanding its reach.
A coalition of Republican-controlled states has challenged the five-decade-old waiver provisions in the Clean Air Act as unconstitutional. That case is scheduled for oral argument before a Washington, D.C., court in September.
The two waivers approved by EPA on Friday cover a suite of rules set by state regulators.
In addition to the Advanced Clean Trucks rule, the first waiver allows California to enforce a regulation requiring shuttle operators serving California’s 13 biggest airports to transition to entirely zero-emission vehicles by the end of 2035. It also lets states set certification requirements for zero-emission powertrains.
The second waiver extends the emission warranty period for heavy-duty trucks from 100,000 miles to 350,000 miles, lengthening the period manufacturers must repair or replace certain parts in vehicles’ pollution control systems. California regulators said longer warranty periods were appropriate because well-maintained engines can last much longer now.
EPA in December finalized a federal truck NOx rule that is slightly less stringent than California’s requirements, reducing NOx emissions about 80 percent.
The California Air Resources Board will vote in April on a rule requiring all sales of new trucks to be zero-emission by 2040.