With today's action, EPA is adjusting the volatile organic compound (VOC) performance standard under Phase II of the reformulated gasoline (RFG) program for ethanol RFG blends containing 3.5 weight percent oxygen (10 volume percent ethanol) sold in the Chicago and Milwaukee RFG areas. As discussed in the Notice of Proposed Rulemaking for this adjustment, the EPA is exercising its discretion under Section 211(k)(1) of the Clean Air Act which directs EPA, in promulgating emission reduction standards for RFG, to consider the cost of achieving such emission reductions as well as any nonair-quality and other air- quality related health and environmental impacts. This adjustment reduces by 2.0 percentage points (equivalent to an increase in Reid Vapor Pressure (RVP) of approximately 0.3 pounds per square inch (psi)) the summertime VOC performance standard applicable to RFG blends containing 10 volume percent ethanol.