40 C.F.R. § 81.64
The Huntington (West Virginia)-Ashland (Kentucky)-Portsmouth-Ironton (Ohio) Interstate Air Quality Control Region is revised to consist of the territorial area encompassed by the boundaries of the following jurisdictions of described area (including the territorial area of all municipalities (as defined in section 302(f) of the Clean Air Act, 42 U.S.C. 1857h(f) ) geographically located within the outermost boundaries of the area so delimited):
In the State of Kentucky: Bath County, Boyd County, Bracken County, Carter County, Elliott County, Fleming County, Greenup County, Lawrence County, Lewis County, Mason County, Menifee County, Montgomery County, Morgan County, Robertson County, Rowan County.
In the State of Ohio: Adams County, Brown County, Gallia County, Lawrence County, Scioto County.
In the State of West Virginia: Cabell County, Mason County, Wayne County.
40 C.F.R. §81.64