Radon Testing in York County, PA
Radon testing in York County, PA starts with picking a test length: a short-term test (2-90 days) gives a fast snapshot, while a long-term test (over 90 days) accounts for seasonal variation and gives a more reliable picture. DIY kits sold at hardware stores are a reasonable first step; a result at or above 4 pCi/L on either type is when radon mitigation in York County, PA planning starts.
Short-term vs. long-term
Radon levels fluctuate with weather, season, and how a house is used (windows open vs. closed, HVAC running or not). A short-term test is faster and cheaper but more sensitive to whatever conditions happened during that window. A long-term test smooths that out and is considered more representative of year-round average exposure. Real estate transactions almost always use a short-term test because of closing timelines; a homeowner with no deadline gets a more accurate picture from a long-term test.
DIY kits vs. professional testing
Charcoal-canister DIY kits, available at most hardware stores for $15-30, are a legitimate, EPA-recognized method for an initial short-term test. A professional test with continuous radon monitoring equipment costs more ($150-700, per our cost guide) but is standard for real estate transactions and gives real-time data rather than a single averaged number.
How to actually run a DIY test
- Place the kit in the lowest lived-in level of the home (a finished basement counts; an unfinished crawlspace used only for storage does not)
- Keep windows and exterior doors closed as much as normal during the test period
- Avoid running the kit during unusually high winds or right after a big weather change, which can skew a short-term result
- Mail the kit to the lab promptly once the test period ends; a delayed mail-in affects accuracy
What your number means
Below 2 pCi/L: generally low priority. Between 2 and 4 pCi/L: worth considering mitigation, especially for a long-term result. At or above 4 pCi/L: the EPA's standard action level, mitigation recommended. See our radon and health guide for why there's no fully "safe" number, just a practical threshold.
Where the device goes, and why placement changes the number
A radon measurement is a measurement of one location, not of a house. Move the device and you get a different answer, which is why the placement rules exist and why a result with no stated location is not really a result.
- The lowest lived-in level, or the lowest level that could reasonably become living space
- 20 inches to 6 feet above the floor
- At least 3 feet from exterior walls, windows and doors
- At least 4 inches from any other object
- Away from draughts, heat, direct sunlight and high humidity
- Not in a kitchen, bathroom or laundry room
- Somewhere it will not be knocked, moved or covered for the full test period
Basements read higher than upper floors, so an unfinished basement result and a first-floor result are answering different questions. If the basement is never occupied, the lowest lived-in level is the honest place to measure, though a basement reading is still useful if that space might be finished later.
Closed-house conditions, and what invalidates a test
A short-term test only means anything if the house is kept closed. That means windows and external doors shut, except for normal entry and exit, for 12 hours before the test begins and throughout it. Heating and air conditioning run normally, but whole-house fans, window fans and attic fans stay off.
Things that invalidate a result outright: a window left open, a device moved partway through, a device that spent the test on a windowsill or next to a dryer, a whole-house fan running, or a test period shorter than the device requires. In real estate testing these conditions are not always respected, and the breaches are not always accidental, which is the argument for a certified measurement professional running a transaction test rather than a kit left out by a seller.
Device types
| Device | Duration | Notes |
|---|---|---|
| Charcoal canister | 2 to 7 days | Cheapest. Mailed to a lab, so add turnaround time |
| Liquid scintillation vial | 2 to 7 days | Similar, lab analysed |
| Alpha-track detector | 90 to 365 days | The standard long-term device. Integrates across seasons |
| Electret ion chamber | Short or long | Reusable, used more by professionals than homeowners |
| Continuous radon monitor | 48 hours+ | Professional device. Logs hourly, so tampering and weather effects are visible in the data |
| Consumer digital monitor | Ongoing | Useful for watching trends over time. Not a substitute for a lab-analysed test in a transaction |
A continuous monitor's hourly log is the reason professionals use them for real estate work: if a window was opened on day two, the graph shows it.
When to retest
- Every two years after mitigation, generally in the basement and preferably during the heating season, per DEP
- Every few years even without a system, if the first result was below 4
- After any foundation, structural or HVAC work, because changing the building changes its pressures
- After finishing a basement, since a space that was not lived in now is
- Before listing a house, so you hold a current number rather than reacting to the buyer's
- After a radon fan replacement
Next: short-term vs long-term and what to do with the number you get.