Rankings · Place

Highest radon potential by state

EPA radon potential zone.

This measure has no better end. The order describes the states, it does not rank them — see the other direction.

EPA county screening guidance, not a measurement for any individual home. Zone 1 is the highest potential and average indoor levels may exceed 4 pCi/L; Zone 2 is moderate, roughly 2–4 pCi/L; Zone 3 is lower, below 2 pCi/L. State profiles show the most-populous official county zone; the U.S. view shows the population-weighted share of residents in the selected zone. County shading identifies counties in that zone. EPA says all homes should be tested, regardless of zone.

  1. 1IowaZone 100
  2. 2North DakotaZone 100
  3. 3ColoradoZone 98
  4. 4WyomingZone 97
  5. 5MaineZone 89
  6. 6MontanaZone 84
  7. 7NebraskaZone 83
  8. 8MinnesotaZone 81
  9. 9PennsylvaniaZone 77
  10. 10South DakotaZone 72
  11. 11IndianaZone 72
  12. 12ConnecticutZone 67
  13. 13OhioZone 63
  14. 14KansasZone 55
  15. 15MarylandZone 52
  16. 16TennesseeZone 52
  17. 17MassachusettsZone 47
  18. 18KentuckyZone 45
  19. 19New MexicoZone 45
  20. 20VirginiaZone 44
  21. 21WisconsinZone 42
  22. 22West VirginiaZone 39
  23. 23GeorgiaZone 33
  24. 24Rhode IslandZone 27
  25. 25IllinoisZone 27
  26. 26New JerseyZone 24
  27. 27IdahoZone 24
  28. 28New YorkZone 23
  29. 29AlabamaZone 23
  30. 30MissouriZone 22
  31. 31WashingtonZone 15
  32. 32MichiganZone 12
  33. 33South CarolinaZone 10
  34. 34NevadaZone 6
  35. 35North CarolinaZone 6
  36. 36UtahZone 4
  37. 37New HampshireZone 4
  38. 38CaliforniaZone 3
  39. 39AlaskaZone 0
  40. 40ArkansasZone 0
  41. 41ArizonaZone 0
  42. 42District of ColumbiaZone 0
  43. 43DelawareZone 0
  44. 44FloridaZone 0
  45. 45HawaiiZone 0
  46. 46LouisianaZone 0
  47. 47MississippiZone 0
  48. 48OklahomaZone 0
  49. 49OregonZone 0
  50. 50TexasZone 0
  51. 51VermontZone 0
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<iframe src="https://movermath.com/embed/radon-potential" width="100%" height="420" style="border:0" loading="lazy" title="EPA radon potential zone by state"></iframe>

Source: U.S. Environmental Protection Agency, Map of Radon Zones. · How this is built