How to test for radon in Massachusetts
What does your radon number mean?
| Your result | What it means |
|---|---|
| 4.0 or higher | At or above the EPA action level. The Massachusetts Department of Public Health says to fix a home at 4 pCi/L or higher. Massachusetts' health department says levels above 100 pCi/L may need additional safeguards. Call the Massachusetts Radon Hotline: (800) 723-6695. The EPA recommends a follow-up test before deciding on a fix. For a home sale, it describes a different approach: two short-term tests run at the same time. |
| 2.0 to 3.9 | Below the action level, but not zero risk. The EPA recommends considering a fix between 2 and 4 pCi/L. No radon level is risk-free. |
| Below 2.0 | Below the level where action is suggested. That's below the range where the EPA suggests considering a fix. For comparison, outdoor air is about 0.4 pCi/L, and no home reads zero. |
Radon is usually higher in winter. Massachusetts suggests testing between November 1 and March 31, so a winter retest is worth doing.
Massachusetts recommends retesting a home with a system every year or two to make sure it's working. A result at or above 4 pCi/L with a system in place means it needs attention.
This is general guidance from the Massachusetts Department of Public Health and the EPA, not a diagnosis of your home.
Pick the right time
The state health department says winter is the best time to test, because windows and doors are closed and the heat is on. Its suggested window is November 1 through March 31, when levels are usually higher. If a summer test came back low, test again in winter.
Two ways to test
- Do it yourself. Short-term kits are sold online and in hardware and home improvement stores. Most run two to three days; leave yours in place as long as the package says. The state no longer gives out free kits, but it points to discounted kits from Kansas State University's radon program.
- Hire a certified professional. The state health department advises using a professional certified by AARST/NRPP or the National Radon Safety Board (NRSB). That's the better choice when a buyer, seller or landlord needs to rely on the result.
Where to put the kit
From the state's testing guidance:
- The lowest level of the home where people spend time
- On a flat surface such as a table, at least 20 inches off the floor
- At least 4 inches from other objects
- At least 1 foot from exterior walls, or 3 feet from exterior walls with doors or windows
- Away from drafts, heat and humidity, such as a washer or dryer
- Not in a kitchen, laundry room, bathroom or closet
Keep the house closed
- Close windows and outside doors at least 12 hours before a two- or three-day test, and keep outside doors shut as much as you can during it.
- Run heating and cooling fans that recirculate indoor air.
- Don't run whole-house fans that pull in outside air, and don't use the fireplace.
- Don't test during storms, high winds over 30 mph, or unusually warm weather.
Renting?
Ask your landlord to test. If they won't, you can test yourself. Tenants usually can't make the repairs, so the building owner generally does.