The EPA is taking direct final action partially approving and partially disapproving revisions to the State Implementation Plan (SIP) submitted by the designee of the Governor of Wyoming on August 9, 2000; August 7, 2001; and August 13, 2001. These revisions are intended to restructure and modify the State's air quality rules so that they will allow for more organized expansion and revision and are up to date with Federal requirements. The August 9, 2000 revisions include a complete restructuring of the Wyoming Air Quality Standards and Regulations (WAQSR) from a single chapter into thirteen separate chapters. In addition to restructuring the regulations, the State's August 9, 2000 revisions also update the definition in Chapter 3, Section 6 Volatile organic compounds (previously Chapter 1, Section 9) and include revisions to Chapter 6, Section 4 Prevention of significant deterioration (PSD) (previously Chapter 1, Section 24). The August 7, 2001 revisions include the addition of a credible evidence provision and another update to the definition of VOC. The August 13, 2001 revisions include changes to the State's particulate matter regulations. We partially approve these SIP revisions because they are consistent with Federal requirements. We are partially disapproving the provisions of the State's submittal that allow the Administrator of the Wyoming Air Quality Division (WAQD) to approve alternative test methods in place of those required in the SIP, because such provisions are inconsistent with section 110(i) of the Clean Air Act (Act) and the requirement that SIP provisions can only be modified through revisions to the plan that must be approved by EPA. We are taking these actions under section 110 of the Act. We are not acting on Chapter 8, Section 4 Transportation Conformity (part of the August 9, 2000 submittal) or on the PM<INF>2.5</INF> revisions in Chapter 1 and Chapter 2 of the State's August 13, 2001 submittal.