Oklahoma: 77 counties covered
Of 77 rated Oklahoma counties, 0 are in EPA's highest radon-potential zone (Zone 1) — but every county page links to testing guidance regardless of zone, because a county rating is a county-wide average, not a reading for any one house.
- Oklahoma County
- Tulsa County
- Cleveland County
- Canadian County
- Comanche County
- Rogers County
- Wagoner County
- Payne County
- Pottawatomie County
- Creek County
- Muskogee County
- Garfield County
- Grady County
- Washington County
- Logan County
- Bryan County
- Le Flore County
- Carter County
- Cherokee County
- McClain County
- Osage County
- Stephens County
- Kay County
- Pittsburg County
- Delaware County
- Sequoyah County
- Mayes County
- Pontotoc County
- Okmulgee County
- Lincoln County
- McCurtain County
- Ottawa County
- Custer County
- Caddo County
- Garvin County
- Jackson County
- Seminole County
- Beckham County
- Texas County
- Woodward County
- Adair County
- McIntosh County
- Marshall County
- Pawnee County
- Kingfisher County
- Atoka County
- Craig County
- Choctaw County
- Murray County
- Hughes County
- Haskell County
- Okfuskee County
- Noble County
- Washita County
- Pushmataha County
- Love County
- Johnston County
- Nowata County
- Latimer County
- Woods County
- Blaine County
- Kiowa County
- Major County
- Tillman County
- Alfalfa County
- Cotton County
- Greer County
- Coal County
- Jefferson County
- Beaver County
- Dewey County
- Grant County
- Ellis County
- Roger Mills County
- Harper County
- Harmon County
- Cimarron County