Plympton has the thinnest radon record in this service area: 131 tests reported to Massachusetts DPH across ten years, with 15 of them at or above 4.0 pCi/L. The town median sits at 1.7 pCi/L and the highest reading on record is 21.0.
A sample that small tells you very little about any particular house, and that is worth saying plainly rather than dressing up a percentage.
Massachusetts DPH publishes every radon test result reported in the state by town. Here is what 131 Plympton tests from 2015 through 2024 look like.
| Measure | Plympton, MA | What it means |
|---|---|---|
| Tests on record, 2015-2024 | 131 | The sample this table is built on |
| Median result | 1.7 pCi/L | Half of Plympton homes tested came in below this |
| Geometric mean | 1.9 pCi/L | The typical result, with outliers damped |
| Tests at or above 4.0 pCi/L | 15 (11.5%) | EPA says fix the house at this level |
| Tests between 2.0 and 4.0 | 31.3% | EPA says consider fixing |
| Tests below 2.0 | 57.3% | No action recommended |
| Highest single result on record | 21 pCi/L | One house, not the town, but it was somebody's house |
| Tests per 1,000 occupied homes | 132.5 | How thoroughly the town has actually been checked |
Source: Massachusetts Department of Public Health radon testing data, town-level export, 2015-2024.
Thirteen tests a year across the whole town is not a dataset you should bet a house on. The 11.5% figure at or above the action level is real, but it rests on 15 houses, and a handful of results either way would move it several points. Towns with thousands of tests have stable averages. Plympton does not.
What is reliable here is the geology and the housing stock. Rural lots, private wells, and full basements under older homes are the exact combination that produces elevated readings everywhere else in this county, and Plympton has all three. The glacial deposits under Plympton do not stop at the Kingston line.
So the honest answer for Plympton is the EPA's own: test the house. The town average cannot do that job here, and pretending otherwise would be inventing confidence that the data does not support.
The EPA Map of Radon Zones assigns Plymouth County to Zone 2, which predicts an average indoor screening level between 2.0 and 4.0 pCi/L. Barnstable, Bristol and Norfolk counties carry the same designation. Worcester, Middlesex and Essex are Zone 1.
The EPA prints a warning on the same map: it should not be used to decide whether an individual home gets tested, and all homes should be tested regardless of zone. The Plympton numbers in the table above show why. A county-wide prediction cannot tell you what is under one address.
Massachusetts does not license radon contractors. The state's own guidance points homeowners at professionals certified by NRPP or NRSB, and those two certifications are the only credential worth asking about. Ask for the number, not the logo.
An active system puts a fan in the vent stack, and wiring that fan is electrical work, so the Plympton wiring inspector is normally the one permit stop on a mitigation job. We pull it. Systems that vent above the roofline and discharge away from windows meet the EPA protocol the inspector is checking against.
State testing data says yes for a meaningful share of houses. Of 131 Plympton tests on record from 2015 through 2024, 11.5% came back at or above the EPA's 4.0 pCi/L action level, and another 31.3% landed between 2.0 and 4.0. The town median is 1.7 pCi/L.
Most single-family systems in this county run $1,200 to $2,500 installed, with a post-mitigation retest included. The price turns on foundation type and how many suction points the slab needs, which is why we quote in writing after seeing the house.
A short-term test needs a minimum of 48 hours under closed-house conditions. We use continuous monitors that log hourly, so a test placed Monday is reported Wednesday. Real estate deadlines get priority placement.
Nothing in Massachusetts law requires one, but radon testing is standard practice in home-sale inspections here, and buyers routinely ask for mitigation or a credit when a result comes back high. Testing inside the inspection window costs less than renegotiating after you own it.
Plympton is a small town, and the state record only counts tests that labs and professionals actually report. 131 tests over ten years works out to about thirteen a year. The percentages calculated from that sample move a lot with a few results, so treat them as background rather than as a prediction about your address.
One call covers testing, mitigation, well-water treatment and system repair anywhere in Plympton and the rest of Plymouth County. Written quote first, retest after.
Sources: Massachusetts Department of Public Health radon testing data 2015-2024; EPA Map of Radon Zones, Massachusetts.
Radon Mitigation for Plymouth and Plymouth County. Test it. Fix it. Prove it's fixed.
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