Massachusetts Radon Map, Levels & Testing Guide
Browse the 1 listed county page surfaced for Massachusetts. Open a listed county to compare its EPA zone, source caveats, testing meaning, and when mitigation pricing becomes worth checking.
High Risk
Moderate
Low Risk
Official Evidence in Massachusetts
1 of 1 listed counties have official evidence
Open a county page to see the official source context: measurement fields, local burden, state percentile, and the next step for no reading, 2.0-3.9, or 4.0+ pCi/L.
100%
covered
Measured
1
State source
0
CDC source
1
Needs source detail
0
Measured Risk Leaders in Massachusetts
County rankings from actual reported radon tests
These lists rank the visible Massachusetts county pages by measured radon signals, not by the EPA zone label alone. Use them to spot where the state hub has a real data story before opening individual county pages.
1
measured counties
State-level evidence read
This hub has official measurement coverage, but most visible counties need home-specific confirmation.
The state hub is now doing a decision job: it separates first-click counties, retest counties, and lower-signal counties from 1 visible county measurement rows. None of the visible measured counties cross the elevated band, so the hub should emphasize home-specific testing rather than implied statewide danger.
First-click counties
Open Plymouth County first when you need the strongest local answer. It is tagged Retest lane from 17.0% 4.0+ - 2.6 pCi/L primary - 6,993 tests. 0 visible measured counties are elevated or high enough to review before lower-signal counties.
Buyer/seller lane
Buyer/seller lane: use the hub to pick the county page, but do not negotiate from statewide context alone. A property result still controls quotes and credits.
Retest lane
Retest lane: with 1 measured county rows and no elevated statewide cluster, 2.0-3.9 pCi/L is mostly a confirm-or-monitor decision until a home repeats higher.
Best county pages to open first
Start with these local evidence pages
Ranked by measured burden, 4.0+ share, test volume, and whether the EPA zone understates the measurement signal.
Highest 4.0+ share
Highest high-end reading
Most reported tests
Measured pattern
Among 1 visible counties with measurement tables, 0 land in the high measured-burden band and 0 land in high or elevated measured-burden bands. That lets this hub rank counties by observed test distribution instead of repeating the EPA map.
Map vs measurements
The strongest measured signals mostly align with the EPA zone structure, so the county pages can use the map as support while still leading with test data.
Source strategy
The measured rows shown here use CDC Tracking. This is still official evidence, but the hub should keep source caveats visible until a stable state table is available.
Already Tested
View Massachusetts Cost Estimates
If you already have a radon result, skip the directory and move straight to local price guidance.
Understand the Number
2.0 vs 4.0 vs 8.0 pCi/L
Use the parent levels guide if you need the plain-English meaning of a radon result before browsing counties.
Need a Number First
Read the Testing Guide
Use the fastest valid radon test setup before you compare quotes or ask whether mitigation is worth it.
Browse Counties
Jump to the Directory
Open your county to see its EPA zone, testing meaning, and the point where mitigation becomes worth pricing.
Official State Resource
Massachusetts radon program and rules
Use the state program link to verify local radon guidance, disclosure language, and contractor credential expectations before you act on an estimate.
Disclosure note
Massachusetts does not have a mandatory seller disclosure form. Radon disclosure is not specifically required but concealment of known issues creates legal liability.
Credential note
Massachusetts does not require state licensing for radon professionals.
Already tested? Get your itemized mitigation cost estimate.
View Massachusetts Mitigation Cost Estimates ->