Radon levels in Massachusetts: Low
The model predicts a population-weighted basement average of 1.8 pCi/L (model estimate) across Massachusetts's 14 counties - close to the US average of 1.8 pCi/L. Above-ground floors average 1.1 pCi/L.
Predicted (model estimate). The pCi/L figures on this page are long-term area averages from a peer-reviewed national model built on millions of real radon tests (2001-2021). They describe the typical home in this area - not your home, which can be several times higher or lower. The EPA radon zone is a separate, 1993 county-level classification. How the numbers work.
3 / 14
EPA Zone 1 counties (21%)
10 / 1
Zone 2 / Zone 3 counties
0
counties predicted ≥ 4 pCi/L
0.4%
of ZIP codes predicted ≥ 4 pCi/L
Test Massachusetts once anyway - radon varies house to house
The predicted basement average here is 1.8 pCi/L, below the EPA's 2 pCi/L "consider fixing" threshold. That's good news for the area - but the EPA still recommends every home be tested, because foundation cracks, soil pockets and ventilation make one house very different from its neighbor. One inexpensive kit settles it.
Monitor link goes to the Airthings store - use code RADONGRADE-10OFF at checkout for 10% off any Airthings monitor.
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What the data says about radon in Massachusetts
According to the EPA zone map, 3 of Massachusetts's 14 counties are EPA Zone 1 (21%), 10 are Zone 2 and 1 is Zone 3. Zone 2 (predicted screening average of 2-4 pCi/L) is the most common designation, with the 3 Zone 1 counties marking where the EPA expected the highest potential. Treat the map as a coarse prior: it predates two decades of test data and never replaces a test in your own home.
The 2001-2021 national model predicts a population-weighted basement average of 1.8 pCi/L for Massachusetts (low range, close to the US average of 1.8). Of the 14 counties with predictions, 0 are predicted at or above 4 pCi/L, 1 in the 2-4 band and 13 below 2. The highest predicted county is Worcester County at 2.5 pCi/L; the lowest is Suffolk County at 1.2 - a 1.3 pCi/L spread that means a statewide average tells you little about any one county.
34.8% of the state's modeled ZIP codes are predicted at or above 2 pCi/L, and 0.4% at or above the 4 pCi/L action level - below the national shares of 4.2% and 48.7%. The 4+ ZIPs are where a first test is most urgent; the 2-4 ZIPs are where results most often surprise people.
Massachusetts counties by predicted radon
Sorted highest to lowest predicted basement average (model estimate). 14 counties.
| County | Predicted basement | Upstairs | Grade | EPA zone | ZIPs |
|---|---|---|---|---|---|
| Worcester County | 2.5 pCi/L | 1.4 | Moderate | EPA Zone 1 | 78 |
| Essex County | 2.0 pCi/L | 1.4 | Low | EPA Zone 1 | 41 |
| Barnstable County | 2.0 pCi/L | 1.1 | Low | EPA Zone 2 | 38 |
| Dukes County | 1.9 pCi/L | 1.1 | Low | EPA Zone 2 | 7 |
| Middlesex County | 1.8 pCi/L | 1.2 | Low | EPA Zone 1 | 80 |
| Plymouth County | 1.8 pCi/L | 1.0 | Low | EPA Zone 2 | 30 |
| Bristol County | 1.8 pCi/L | 0.9 | Low | EPA Zone 2 | 33 |
| Norfolk County | 1.8 pCi/L | 1.0 | Low | EPA Zone 2 | 39 |
| Berkshire County | 1.7 pCi/L | 1.1 | Low | EPA Zone 2 | 26 |
| Franklin County | 1.6 pCi/L | 0.9 | Low | EPA Zone 2 | 26 |
| Hampshire County | 1.6 pCi/L | 0.8 | Low | EPA Zone 2 | 24 |
| Nantucket County | 1.6 pCi/L | 1.1 | Low | EPA Zone 2 | 1 |
| Hampden County | 1.3 pCi/L | 0.7 | Low | EPA Zone 2 | 35 |
| Suffolk County | 1.2 pCi/L | 0.6 | Low | EPA Zone 3 | 27 |
Radon levels in Massachusetts cities
The 29 most-populous Massachusetts places among the 1,000 largest US cities (Census incorporated places and CDPs), by population. City figures are ZIP-land-weighted means of the model's ZIP predictions (model estimate).
| City | Population | Predicted basement | Upstairs | Grade | ZIPs ≥ 4 |
|---|---|---|---|---|---|
| Boston | 653,833 | 1.3 pCi/L | 0.6 | Low | 0% |
| Worcester | 207,621 | 2.5 pCi/L | 1.1 | Moderate | 0% |
| Springfield | 153,672 | 1.2 pCi/L | 0.6 | Low | 0% |
| Cambridge | 118,214 | 1.3 pCi/L | 0.6 | Low | 0% |
| Lowell | 114,296 | 1.9 pCi/L | 1.2 | Low | 0% |
| Brockton | 104,890 | 1.6 pCi/L | 0.8 | Low | 0% |
| Quincy | 101,597 | 1.6 pCi/L | 0.8 | Low | 0% |
| Lynn | 101,241 | 1.8 pCi/L | 1.2 | Low | 0% |
| New Bedford | 100,695 | 1.4 pCi/L | 0.8 | Low | 0% |
| Fall River | 93,840 | 1.8 pCi/L | 0.9 | Low | 0% |
| Newton | 88,415 | 1.5 pCi/L | 0.8 | Low | 0% |
| Lawrence | 88,172 | 1.6 pCi/L | 0.9 | Low | 0% |
| Somerville | 80,407 | 1.2 pCi/L | 0.6 | Low | 0% |
| Framingham | 71,875 | 1.6 pCi/L | 1.2 | Low | 0% |
| Haverhill | 67,415 | 2.0 pCi/L | 1.4 | Moderate | 0% |
| Malden | 65,133 | 1.4 pCi/L | 1.8 | Low | 0% |
| Waltham | 64,477 | 1.6 pCi/L | 1.0 | Low | 0% |
| Taunton | 60,412 | 1.7 pCi/L | 0.9 | Low | 0% |
| Weymouth | 59,114 | 1.9 pCi/L | 1.0 | Low | 0% |
| Medford | 58,744 | 1.8 pCi/L | 0.7 | Low | 0% |
| Brookline | 58,732 | 1.5 pCi/L | 0.7 | Low | 0% |
| Revere | 57,954 | 1.2 pCi/L | 0.6 | Low | 0% |
| Chicopee | 54,838 | 1.0 pCi/L | 0.6 | Low | 0% |
| Peabody | 54,056 | 2.0 pCi/L | 1.4 | Moderate | 0% |
| Methuen | 53,455 | 1.9 pCi/L | 1.4 | Low | 0% |
| Everett | 50,318 | 1.1 pCi/L | 0.5 | Low | 0% |
| Barnstable | 49,709 | 1.8 pCi/L | 1.1 | Low | 0% |
| Attleboro | 46,654 | 2.1 pCi/L | 1.0 | Moderate | 0% |
| Salem | 44,744 | 1.6 pCi/L | 1.1 | Low | 0% |
Highest-radon ZIP codes in Massachusetts
The 10 Massachusetts ZIP codes with the highest predicted basement average (model estimate), out of 485 modeled. A ZIP average is still an area figure - neighboring homes routinely test several pCi/L apart.
| ZIP | County | Predicted basement | Upstairs | Grade |
|---|---|---|---|---|
| 01505 | Worcester County | 4.4 pCi/L | 2.2 | High |
| 01571 | Worcester County | 4.1 pCi/L | 2.1 | High |
| 01501 | Worcester County | 3.5 pCi/L | 1.8 | Moderate |
| 01520 | Worcester County | 3.3 pCi/L | 1.9 | Moderate |
| 01570 | Worcester County | 3.3 pCi/L | 1.5 | Moderate |
| 01524 | Worcester County | 3.2 pCi/L | 1.9 | Moderate |
| 01540 | Worcester County | 3.1 pCi/L | 1.7 | Moderate |
| 01583 | Worcester County | 3.1 pCi/L | 1.8 | Moderate |
| 01430 | Worcester County | 3.1 pCi/L | 1.8 | Moderate |
| 01560 | Worcester County | 3.1 pCi/L | 1.7 | Moderate |
Massachusetts radon questions
- Is radon high in Massachusetts?
- Massachusetts's population-weighted predicted basement average is 1.8 pCi/L, close to the US average of 1.8. 0 of its 14 modeled counties are predicted at or above the EPA action level of 4 pCi/L, 1 are in the 2-4 "consider fixing" range and 13 are below 2. 0.4% of Massachusetts ZIP codes are predicted at 4 or higher.
- Which Massachusetts county has the highest radon?
- Worcester County has the highest predicted basement average in Massachusetts at 2.5 pCi/L (EPA Zone 1). The lowest is Suffolk County at 1.2 pCi/L. These are area figures; individual homes in any county can test far higher.
- How many EPA Zone 1 counties are in Massachusetts?
- 3 of Massachusetts's 14 counties (21%) are EPA Zone 1 (highest potential), 10 are Zone 2 and 1 are Zone 3. The EPA zone map dates from 1993; the predicted values on this page come from a 2001-2021 model built on millions of actual tests, so the two can disagree for a given county.
- Should I test for radon in Massachusetts?
- Yes. Even though Massachusetts's predicted average is below 2 pCi/L, the EPA recommends every home be tested - radon varies house to house, and 34.8% of Massachusetts ZIP codes are still predicted at 2 pCi/L or higher.
Massachusetts radon program
State programs keep lists of certified testers and mitigators and sometimes run kit programs. We link only pages we could verify, and Massachusetts's program page did not respond when we checked, so start from the EPA state radon contacts page. Then read how to test and what mitigation costs.