The conference report on the energy bill (H.R. 6), which came to the House and Senate floor for action the week of November 17, 2003, contained several Clean Air Act provisions. Most of these are also contained in S. 2095, a revised version of the bill introduced February 12, 2004, and in H.R. 4503, which passed the House June 15, 2004. Most of the air provisions concern the gasoline additives MTBE and ethanol, used to meet Clean Air Act requirements that reformulated gasoline (RFG) sold in the nation’s worst ozone nonattainment areas contain at least 2% oxygen, to improve combustion.