[lakhim]

Map of roughly risk of radon: https://www.epa.gov/sites/default/files/2015-07/documents/zo...

Given that lung cancer is driven by a) smoking, then b) radon, one would expect some level of correlation here.

[rufus_foreman]

That map makes it looks like the borders of Missouri were decided based on radon risk. Which is not what I think actually happened when they drew those borders.

So, no, don't believe your map.

[bxparks]

The granularity of the map seems to be at the county level, so I will guess that the EPA did not gather this data by itself, but rather, rely on self-reported data from each county from each state. A county is a political boundary, so the state of Missouri probably had different testing regulations and methodologies than its neighbors like Iowa and Illinois.