Mississippi: 82 counties covered
Of 82 rated Mississippi 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.
- Harrison County
- Hinds County
- DeSoto County
- Rankin County
- Jackson County
- Madison County
- Lee County
- Forrest County
- Lauderdale County
- Lamar County
- Jones County
- Lafayette County
- Pearl River County
- Lowndes County
- Oktibbeha County
- Hancock County
- Warren County
- Washington County
- Pike County
- Lincoln County
- Marshall County
- Alcorn County
- Monroe County
- Panola County
- Pontotoc County
- Neshoba County
- Adams County
- Tate County
- Bolivar County
- Union County
- Scott County
- Copiah County
- Leflore County
- George County
- Simpson County
- Prentiss County
- Itawamba County
- Marion County
- Sunflower County
- Yazoo County
- Leake County
- Tippah County
- Newton County
- Grenada County
- Coahoma County
- Wayne County
- Stone County
- Tishomingo County
- Clay County
- Covington County
- Winston County
- Attala County
- Chickasaw County
- Jasper County
- Holmes County
- Clarke County
- Smith County
- Walthall County
- Greene County
- Calhoun County
- Yalobusha County
- Amite County
- Lawrence County
- Perry County
- Jefferson Davis County
- Tallahatchie County
- Webster County
- Noxubee County
- Montgomery County
- Carroll County
- Tunica County
- Kemper County
- Claiborne County
- Choctaw County
- Wilkinson County
- Benton County
- Franklin County
- Humphreys County
- Jefferson County
- Quitman County
- Sharkey County
- Issaquena County