The Northwest Ohio Intrastate Air Quality Control Region (Ohio) consists of the territorial area encompassed by the boundaries of the following jurisdictions or 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 Ohio: Allen County, Auglaize County, Champaign County, Defiance County, Fulton County, Hancock County, Hardin County, Henry County, Logan County, Mercer County, Paulding County, Putman County, Shelby County, Van Wert County, Williams County.