Ohio Rev. Code Ann. § 303.29

No board of county commissioners shall exercise the authority conferred upon counties by sections 303.26 to 303.56, inclusive, of the Revised Code, until after it has adopted a resolution finding that one or more slum or blighted areas exist in the county; and the rehabilitation, conservation, redevelopment, or combination thereof, of such slum or blighted area or areas is necessary in the interest of the public health, safety, morals, or welfare of the residents of such county.