Marshfield has the cleanest typical result in this service area and one of its larger outliers. Of 1,375 tests, 62.5% landed below 2.0 pCi/L, the median sits at 1.5, and yet 207 houses still came back at or above 4.0 and one reached 48.2.
A good town average is not a good reason to skip the test, and in Marshfield the reason is usually sitting one floor down.
Massachusetts DPH publishes every radon test result reported in the state by town. Here is what 1,375 Marshfield tests from 2015 through 2024 look like.
| Measure | Marshfield, MA | What it means |
|---|---|---|
| Tests on record, 2015-2024 | 1,375 | The sample this table is built on |
| Median result | 1.5 pCi/L | Half of Marshfield homes tested came in below this |
| Geometric mean | 1.6 pCi/L | The typical result, with outliers damped |
| Tests at or above 4.0 pCi/L | 207 (15.1%) | EPA says fix the house at this level |
| Tests between 2.0 and 4.0 | 22.5% | EPA says consider fixing |
| Tests below 2.0 | 62.5% | No action recommended |
| Highest single result on record | 48.2 pCi/L | One house, not the town, but it was somebody's house |
| Tests per 1,000 occupied homes | 136.2 | How thoroughly the town has actually been checked |
Source: Massachusetts Department of Public Health radon testing data, town-level export, 2015-2024.
South Shore capes and split-levels in Marshfield tend to use the lower level as real living space: the family room, the home office, the bedroom a teenager moved into. Radon concentration is highest at the lowest level, so the room people actually occupy is the room the measurement has to come from.
EPA protocol puts the monitor in the lowest lived-in level, not the lowest level that exists. A test run on the first floor of a Marshfield split-level will read lower than the basement bedroom below it, and the number that matters is the one where somebody sleeps.
That is also why Marshfield's 1.5 median is less reassuring than it looks. A town whose houses test clean on average can still have 207 households living above the action level, and the finished basement is where they turn up.
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 Marshfield 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 Marshfield 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 1,375 Marshfield tests on record from 2015 through 2024, 15.1% came back at or above the EPA's 4.0 pCi/L action level, and another 22.5% landed between 2.0 and 4.0. The town median is 1.5 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.
The lowest level anyone actually lives in. If the basement holds a family room, an office or a bedroom, that is the test location under EPA protocol, not the floor above it. Testing a level nobody uses produces a number that does not describe anybody's exposure.
One call covers testing, mitigation, well-water treatment and system repair anywhere in Marshfield 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.
(508) 503-6186