The state of radon and air, by data release

Each time the federal sources refresh, this report reads the whole picture back out of them: how many of the 3,143 US counties fall in the highest radon zone, which states carry the most, and the counties whose monitored air was worst that year. It is a companion to the county pages, not a replacement: every figure here is a count over the same federal rows those pages show.

Environmental exposure data only. A radon zone describes a county, never an individual home, and nothing here is medical advice or a diagnosis.