The U.S. Environmental Protection Agency and the U.S. Dept. of Transportation have put forth the first national standards to cut greenhouse-gas emissions and raise the fuel efficiency of heavy-duty trucks and buses.

The proposal, which the agencies announced on Oct. 25, would apply to work vehicles ranging from large, heavy-duty pickup trucks in Class 2b to the largest Class 8 tractor-trailer trucks, weighing 80,000 lb or more. The EPA and DOT action follows a directive issued by President Obama.