The EPA also has moved to regulate greenhouse gases from stationary sources such as power plants and factories.
Starting next year the EPA will require large power plants, manufacturers and oil refiners to get permits for releasing greenhouse gas emissions, though details are unclear.
The EPA will also require industrial sources to submit analyses on the so-called "best available technology" they could add to their plants to cut emissions under the existing Clean Air Act.
The official said the EPA will put out guidance this month that would help companies determine which technologies -- perhaps moving to cleaner-burning natural gas and away from coal -- would make the most sense.
In addition, the EPA is working on rules to cut emissions of mercury from coal-burning power plants and cement plants and on toughening rules on coal ash. In combination, the rules could help force inefficient coal plants into early retirement.