Massachusetts Radon Map, Levels & Testing Guide
Browse the 14 listed county pages surfaced for Massachusetts. Open a listed county to compare its EPA zone, source caveats, testing meaning, and when mitigation pricing becomes worth checking.
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Official Evidence in Massachusetts
14 of 14 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
14
State source
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CDC source
14
Needs source detail
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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.
14
measured counties
State-level evidence read
This hub has measured high-burden counties, so the first click should be evidence-led.
The state hub is now doing a decision job: it separates first-click counties, retest counties, and lower-signal counties from 14 visible county measurement rows. 1 counties cross the high measured-burden band, so those pages should answer testing and 4.0+ action questions most directly.
First-click counties
Open Worcester County first when you need the strongest local answer. It is tagged Test-now from 33.5% 4.0+ - 4.5 pCi/L primary - 16,822 tests. 8 visible measured counties are elevated or high enough to review before lower-signal counties.
Buyer/seller lane
Buyer/seller lane: start with the elevated or high counties, require a fresh lowest-level test, and turn any 4.0+ property result into quote or credit math. The hub has 14 CDC-backed county rows to support that routing.
Retest lane
Retest lane: 2.0-3.9 pCi/L deserves more caution in the elevated/high county set than in lower-signal counties. The hub should send those users to county pages before product or cost paths.
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.
Worcester County
CDC Tracking
33.5% 4.0+ - 4.5 pCi/L primary - 16,822 tests
Worcester County is a first-click page: 33.5% of reported tests at or above 4.0 and 4.5 pCi/L primary result. Route no-reading users to a test now and 4.0+ users to quote or credit planning.
Essex County
CDC Tracking
28.7% 4.0+ - 3.8 pCi/L primary - 8,627 tests
Essex County should be opened before lower-signal counties: 28.7% of reported tests at or above 4.0 and 3.8 pCi/L primary result. It is strong enough for testing and retesting language on the hub.
Berkshire County
CDC Tracking
27.1% 4.0+ - 3.6 pCi/L primary - 760 tests
Berkshire County should be opened before lower-signal counties: 27.1% of reported tests at or above 4.0 and 3.6 pCi/L primary result. It is strong enough for testing and retesting language on the hub.
Bristol County
CDC Tracking
23.2% 4.0+ - 3.2 pCi/L primary - 6,113 tests
Bristol County should be opened before lower-signal counties: 23.2% of reported tests at or above 4.0 and 3.2 pCi/L primary result. It is strong enough for testing and retesting language on the hub.
Highest 4.0+ share
Primary result 4.5 pCi/L - high-end 426.0 pCi/L
CDC Tracking
Primary result 3.8 pCi/L - high-end 192.0 pCi/L
CDC Tracking
Primary result 3.6 pCi/L - high-end 55.0 pCi/L
CDC Tracking
Primary result 3.2 pCi/L - high-end 100.0 pCi/L
CDC Tracking
Primary result 3.1 pCi/L - high-end 61.0 pCi/L
CDC Tracking
Highest high-end reading
4.0+ share 22.0% - primary result 3.3 pCi/L
CDC Tracking
4.0+ share 33.5% - primary result 4.5 pCi/L
CDC Tracking
4.0+ share 28.7% - primary result 3.8 pCi/L
CDC Tracking
4.0+ share 17.0% - primary result 2.6 pCi/L
CDC Tracking
4.0+ share 21.2% - primary result 3.1 pCi/L
CDC Tracking
Most reported tests
4.0+ share 22.0% - primary result 3.3 pCi/L
CDC Tracking
4.0+ share 33.5% - primary result 4.5 pCi/L
CDC Tracking
4.0+ share 21.2% - primary result 3.1 pCi/L
CDC Tracking
4.0+ share 28.7% - primary result 3.8 pCi/L
CDC Tracking
4.0+ share 17.0% - primary result 2.6 pCi/L
CDC Tracking
Measured pattern
Among 14 visible counties with measurement tables, 1 land in the high measured-burden band and 8 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
5 elevated measured counties are not EPA Zone 1. Those are the pages where the actual test distribution matters more than a map-only answer.
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 ->