Under the Clean Air Act (CAA or the Act), as amended in 1990, the Environmental Protection Agency (EPA or the Agency) promulgated anti-dumping regulations for conventional gasoline, that is, gasoline not certified as reformulated gasoline (RFG). These regulations require that conventional gasoline not be more polluting than it was in 1990. They also include provisions for the development of individual refinery baselines. The regulations also include provisions which allow a refinery to obtain an adjusted baseline under certain, limited circumstances. Today's regulations modify the requirements of one baseline adjustment and specify the requirements of two new baseline adjustments. Specifically, today's rulemaking modifies the requirements for obtaining a baseline adjustment due to the production of JP-4 jet fuel in 1990. This rule also allows a baseline adjustment for refiners who are now unable to acquire extremely sweet crude oil (that is, crude oil relatively low in sulfur) that had been available in 1990 and from which the gasoline used to develop a 1990 individual baseline was obtained. Finally, this rule allows a baseline adjustment for refineries which have both extremely low baseline sulfur and olefin levels. The criteria for obtaining any baseline adjustment are stringent. As a result, only those refineries which would experience a severe economic burden due to the regulations are allowed the relief provided by a baseline adjustment. Since few refineries qualify for these adjustments and requiring compliance without a baseline adjustment would be of minimal benefit to the environment, the environmental impact of allowing the baseline adjustments is negligible.