Disclosure: some links on this site may become affiliate links. If you buy through one, we may earn a commission at no extra cost to you. Details.
Short-term vs long-term radon tests, and how to test correctly
Short-term tests stay in your home for 2 to 90 days and give a quick answer. Long-term tests stay more than 90 days and are more likely to show your year-round average (EPA Citizen's Guide).
General information only. This page summarizes public guidance from EPA and the Ohio Department of Health. It is not professional radon or medical advice. For questions about your home, contact ODH radon education staff (614-728-0272, [email protected]) or an Ohio-licensed radon professional (ODH).
The two kinds of test
| Short-term | Long-term | |
|---|---|---|
| Length | 2 to 90 days, depending on the device | More than 90 days |
| Common devices | Charcoal canisters, alpha track, electret ion chamber, continuous monitors, charcoal liquid scintillation | Alpha track, electret |
| Best for | A first screen, or a quick decision when paired with a second short-term test | The best picture of your year-round average |
Source: EPA Citizen's Guide to Radon.
EPA's testing steps
- Start with a short-term test. If the result is 4 pCi/L or higher, do a follow-up test to be sure.
- Follow up with either a long-term test (better year-round picture) or a second short-term test (faster). If the first result is more than twice the 4 pCi/L action level, EPA says to take a second short-term test immediately.
- Decide. Fix the home if a long-term result is 4 pCi/L or more, or consider fixing if the average of two short-term tests is 4 pCi/L or more.
Source: EPA Citizen's Guide to Radon. What the numbers mean: radon levels explained.
Setting up the test so the result counts
From EPA's instructions (EPA Citizen's Guide), plus whatever your kit's own directions say:
- Where: the lowest lived-in level (the basement if it's used often, otherwise the first floor), in a regularly used room such as a living room, den or bedroom. Not the kitchen or bathroom.
- Placement: at least 20 inches above the floor, where it won't be disturbed, away from drafts, high heat, high humidity and exterior walls.
- Closed house (short-term tests): keep windows and outside doors closed as much as possible. For a 2 to 3 day test, close them at least 12 hours before starting. Furnace and AC fans that recirculate air are fine; fans that bring in outside air are not.
- Weather: don't run a 2 to 3 day test during unusually severe storms or high winds.
- Finish: leave the kit out as long as the package says, then reseal it and mail it to the lab right away.
When to test again
- If you start using a lower level, such as a finished basement, retest on that level (EPA).
- Test again after major renovations, because they can change radon levels (EPA).
- ODH recommends retesting single-family homes every two years (ODH).
Getting a kit
- Ohio homeowners: ODH says free test kits are available; contact ODH radon education staff at 614-728-0272 or [email protected] (ODH).
- EPA points to discounted kits from the National Radon Program Services at Kansas State University, and notes kits are sold online and in home improvement stores (EPA).
- Home sale or purchase: in Ohio, a test done for someone else must be done by an ODH-licensed radon tester; testing your own home is exempt (Ohio Adm. Code 3701-69-02).
Where to look for options
Sources
Last updated: