On this page
- The short answer by test type
- Why 48 hours is the minimum
- The full timeline of a professional test
- The full timeline of a home kit
- How long does a long-term test take?
- How long does testing take in a home sale?
- How long after mitigation should you test?
- Key takeaways
- Frequently Asked Questions
- Need a fast, certified result?
A short-term radon test runs at least 48 hours, under closed-house conditions that start 12 hours before the test. Many home kits run 2 to 7 days. A long-term test runs more than 90 days. Lab kits add a few days to a couple of weeks for shipping and analysis before you see a result.
The short answer by test type
| Test type | Test period | Time to get results |
|---|---|---|
| Professional continuous monitor | 48 hours minimum | Usually soon after pickup |
| Short-term charcoal kit | 2 to 7 days (per kit directions) | Add mailing plus lab time |
| Short-term electret | 2 to 7 days typical | Read on site or by the provider |
| Long-term alpha track | More than 90 days | Add mailing plus lab time |
| Consumer digital monitor | Ongoing | First readings within about a day; steadier after several days |
The EPA defines short-term tests as lasting 2 to 90 days and long-term tests as lasting more than 90 days. The choice between them affects both your timeline and how well the result reflects your yearly average. Our guide to short-term vs. long-term radon tests covers that choice in depth.
Why 48 hours is the minimum
Radon levels move up and down through the day. They often rise overnight and shift with wind, rain and air pressure. A test shorter than two days could catch one high or low swing and miss the bigger picture.
That is why the EPA and national testing standards set 48 hours as the minimum for a short-term test. For tests of less than four days, the EPA says the house must be under closed-house conditions for 12 hours before the test and during it.
The full timeline of a professional test
Here is how a typical professional test plays out, start to finish:
- 12 hours before setup. Close all windows and outside doors. Normal coming and going is fine.
- Setup (about 15 to 30 minutes). A certified tester places the continuous monitor in the lowest lived-in level and records the start time.
- The test period (48 hours or more). The monitor logs radon every hour. You live in the house as normal, keeping windows and doors shut.
- Pickup. The tester retrieves the monitor and checks the data for gaps or tampering.
- Report. You get a written report with the average and hourly readings.
From the first closed window to a report in hand, most professional tests take about three days.
The full timeline of a home kit
A home kit takes longer from start to finish, because the lab step adds time.
- Buy or order the kit. Store kits are ready now. Mail-order kits, including free state kits, can take a couple of weeks to arrive.
- Close the house for 12 hours.
- Run the test. Follow the kit's directions, usually 2 to 7 days for charcoal.
- Seal and mail it right away. Most labs set a limit on how long a kit can sit before analysis. Late kits may be rejected.
- Wait for the lab. Results usually come by email or mail within a few days to a couple of weeks.
How long does a long-term test take?
A long-term test runs more than 90 days. Many people leave it in place for 3 to 12 months. The longer it runs, the closer it gets to your real year-round average, because it covers both seasons when the house is sealed and seasons when windows are open.
A long-term test is a good choice if you are not in a hurry. It is not practical for a home sale.
How long does testing take in a home sale?
Purchase agreements in Pennsylvania usually give the buyer a short inspection window. A 48-hour professional test fits inside that window. A lab kit can work, but mailing delays can push results past a deadline. That is one reason most buyers use a certified tester with a continuous monitor.
How long after mitigation should you test?
The EPA says the post-mitigation test should run no sooner than 24 hours after the system starts and within 30 days. The test itself still runs 48 hours or more.
Key takeaways
- Short-term tests run at least 48 hours; long-term tests run more than 90 days.
- Closed-house conditions start 12 hours before short-term tests under four days.
- Professional tests usually give results within about three days of starting.
- Lab kits add shipping and lab time on top of the test period.
- For home sales, a 48-hour continuous monitor test fits most deadlines.
Frequently Asked Questions
Can a radon test be done in 24 hours?
Not to EPA and standard testing protocols. The minimum for a valid short-term test is 48 hours.
Can I leave a short-term kit out longer than the directions say?
Stick to the kit's stated range. Charcoal can lose accuracy if left out too long, and the lab may not accept it.
Do I have to stay home during the test?
No. You can live normally and come and go. Just keep windows and outside doors closed except for normal entry.
Need a fast, certified result?
If you are on a deadline, book radon testing in York, PA with a continuous monitor and a written report. Call (717) 356-3035 any time for a same-day callback.