There are three kinds of radon test, they cost very different amounts, and most homeowners are sold the wrong one. Here is how to pick.
Start with a DIY kit
If your question is simply “does my house have a radon problem,” the cheapest correct answer is a do-it-yourself kit. The Johnson County K-State Research & Extension office at 11811 S. Sunset Drive, Suite 1500 in Olathe sells them for roughly $8–15, and that price includes lab analysis. Call 913-715-7000 to confirm availability.
We tell people this before quoting anything, because paying a contractor for a first-pass screening test is usually wasted money. In a county averaging 5.3 pCi/L against an EPA action level of 4.0, you are testing to size a problem, not to discover whether one is plausible.
Short-term tests: 2 to 7 days
A short-term test sits in the lowest lived-in level of the house, with windows and exterior doors kept closed except for normal entry and exit. It gives you a snapshot.
Snapshots move. Radon rises in winter, when the stack effect pulls hardest on the soil beneath the slab and the house is sealed tight. The same home can read 3.1 in July and 6.8 in January. A single short-term result in summer is not proof of a safe house.
Long-term tests: 90 days or more
A long-term test measures across seasons and gets much closer to the annual average you actually breathe. If you are deciding whether to spend money on mitigation and you are not under a deadline, this is the more honest number.
The tradeoff is obvious: you wait a quarter of a year for it.
Continuous monitors: 48 hours, with a paper trail
A continuous radon monitor logs a reading every hour and prints a tamper-evident report. This is what real estate transactions run on, because it shows whether a window got opened on day two.
Continuous monitor testing is the one case where the professional option is clearly worth paying for. Everyone in the transaction needs a number nobody can argue with.
Which test do you actually need?
| Situation | Use |
|---|---|
| General curiosity | DIY short-term kit |
| Deciding on mitigation, no deadline | Long-term, 90+ days |
| Buying or selling a house | Professional continuous monitor |
| Confirming a new system works | Post-mitigation short-term |
| Disputing an earlier result | Professional continuous monitor |
Kansas requires certification for paid testing
Under the Kansas Radon Certification Law, effective 2011, any radon measurement performed for hire requires current KDHE certification, and it is a violation of state law otherwise. Certification runs in two-year terms; Kansas accepts NRPP and NRSB national credentials.
Statute K.S.A. 48-16a10 additionally requires certified contractors and labs to report their measurement data to the state quarterly — the reason Kansas has more than 46,000 measurements on record.
Ask for a certification number before you hire anyone. Verify it with the KDHE Radon Program at 785-296-1560 or kdhe.radon@ks.gov.
What we do
We run certified short-term, long-term and 48-hour continuous monitor testing across Johnson County, and we will tell you when a $10 kit from the Extension office would answer your question just as well.
Want a straight answer about your house? We will tell you whether an $8–15 test kit is enough before we quote anything.
Call (913) 555-0147Common questions
How long does a radon test take?
A short-term test runs 2 to 7 days with the house kept closed. A long-term test runs more than 90 days and gives a better picture of your yearly average. A continuous monitor used for real estate work typically runs 48 hours and produces an hour-by-hour record.
Should I buy a DIY kit or hire a professional?
Buy the kit if you just want to know. The Johnson County Extension office sells them for about $8 to $15 with lab analysis included. Hire a certified pro when someone else will rely on the number: a home sale, a post-mitigation verification, or a disputed earlier result.