The state Department of Health puts out Bulletins for health providers, and its latest on radon can be found here: http://www.epi.alaska.gov/bulletins/docs/b2015_25.pdf.
I had jumped into data for the bulletin that is almost a quarter of a century deep, and found that when looking at the number of tests for a zip code, the highest percentage that have a count over 4 pCi/L fall into the following areas: East of Delta Junction, In Healy on the west side of the Parks Highway (where the Denali Park buildings are located), and Two Rivers, Nome and the Tok area.
Roughly 6 out of 10 tests in these areas were over the EPA’s action level. Now, having said this, remember that these are fairly large zip codes and all except Two Rivers had under 3 dozen samples in each. That is a lot of territory to brand with such few locations. But it does show where homeowners in the past have found above acceptable levels (by the EPA’s standard).
But remember, the only way YOU will know if you have a radon problem…is to test YOUR home!