Knox County, MO: Radon Risk Data
EPA predicts average indoor levels between 2–4 pCi/L · Source: EPA, CDC
Tipper's take on Knox County
Knox County is in EPA Zone 2, a moderate risk classification. The EPA predicts average indoor radon levels between 2 and 4 pCi/L here, which puts most homes below the agency's action level. Some will be above it. CDC testing data puts the county average at 1.6 pCi/L, though the CDC flags this as a small sample size. Treat it as directional, not definitive.
Zone 2 is the one people underestimate. It's easy to hear "moderate" and move on. But within Zone 2, some homes test at 1 pCi/L and others test at 7 pCi/L. The county average doesn't tell you which side your home falls on. Testing does.
A $15 test kit settles the question. If you're below 4 pCi/L, you can genuinely stop thinking about it. If you're above, mitigation systems in Missouri typically cost $800–$2,000 and bring levels down reliably.
Sources: EPA Radon Zone Map, CDC Environmental Public Health Tracking Network
Test Your Home
The only way to know your home's radon level is to test it. Tipper recommends starting with a short-term test kit. It includes the lab fee, takes 48 hours, and costs about $15.
Radon Professionals Serving Missouri
No contractors in our directory are listed specifically for Knox County. These certified pros serve Missouri and may cover your area. Call to confirm.
How Knox County Compares
vs. Missouri Statewide
Knox County's average of 1.6 pCi/L is 2.3 pCi/L below the statewide average.
Frequently Asked Questions: Knox County
If Knox County is Zone 2, do I still need to test?
Yes, and this is the one people miss. Zone 2 means the county-level prediction is between 2 and 4 pCi/L, but individual homes span a much wider range. Some Zone 2 homes test at 1 pCi/L, others at 7 pCi/L. You won't know until you test. A $15 kit answers the question for good.
What is the EPA's action level, and why 4 pCi/L?
The EPA recommends fixing your home if it tests at or above 4 pCi/L (picocuries per liter). There's no completely safe level. Radon exposure is a spectrum. But 4 pCi/L is where the EPA concludes mitigation is clearly cost-effective. The WHO sets a lower reference level of 2.7 pCi/L. If your home is between 2 and 4 pCi/L, mitigation is optional but worth considering, especially in bedrooms.
How often should I retest for radon?
If your home tested below 4 pCi/L and nothing major has changed structurally, retesting every two years is a good habit. Retest immediately after any significant basement renovation, after buying or selling a home, or after installing a mitigation system (to confirm it's working). Radon levels can shift as foundations settle and conditions change.
Is radon worse in basements than upper floors?
Generally, yes. Radon enters through foundation cracks, floor-wall joints, and gaps around pipes, all concentrated at ground level. Basement living spaces and bedrooms tend to have the highest concentrations. Upper floors typically have lower levels, though radon can still build up in poorly ventilated rooms. Test in the lowest livable level of your home first.
State Overview
Radon Data for Missouri