What to Do After a High Radon Test Result

Your radon test came back high. Now what?

First: don't panic. A reading above 4.0 pCi/L means you should act, but it doesn't mean your family is in immediate danger. Radon risk is about long-term exposure -- years, not days. You've got time to make a good decision instead of a rushed one.

Understand What the Number Means

Radon's measured in picocuries per liter (pCi/L). The EPA's action level is 4.0 pCi/L -- that's the threshold where they say you should fix the problem. But here's what most people miss: the EPA also says levels between 2.0 and 4.0 still pose real risk, and homeowners should "consider" mitigation in that range too.

For context, the average indoor radon level in the US is about 1.3 pCi/L. Average outdoor level is 0.4 pCi/L. So if your test shows 6.0 or 8.0 or 15.0, yeah, that's significantly elevated. But it's also fixable.

One thing worth knowing: radon is the second leading cause of lung cancer in the United States, behind smoking. The EPA estimates about 21,000 lung cancer deaths per year are radon-related. That's not a scare tactic -- it's why the action level exists.

Should You Retest?

Depends on the situation.

If your first test was a short-term test (2 to 7 days), a confirmation test isn't a bad idea. Short-term results can swing based on weather, whether your HVAC was running, even whether windows were open. Two options:

Run another short-term test in the same spot under closed-house conditions. If both come back above 4.0, you've got your answer. Or run a long-term test (90 days to 12 months) for a more accurate annual average -- but only if you're not in a hurry.

Selling or buying a house? Skip the retest. Most real estate transactions move forward with mitigation based on a single elevated short-term result. Nobody wants to wait 90 days for a long-term test when there's a closing deadline.

Find the Right Contractor

Look for two things: NRPP certification or NRSB certification. These are the nationally recognized credentials for radon professionals. Some states have their own licensing requirements on top of that -- Pennsylvania and New Jersey both do, for example.

Fair warning: not all contractors are equally thorough. Ask these questions before hiring anyone:

• Are you currently certified? (Verify on the NRPP or NRSB directory)
• Is a post-mitigation test included?
• What system type do you recommend and why?
• What warranty comes with it?
• How soon can you install?

We wrote a full breakdown of 8 questions to ask before hiring. Worth reading before you call anyone.

What to Expect on Timeline

Installation takes a day. Seriously -- most residential systems go in within 4 to 8 hours. Scheduling's the bottleneck. During real estate season (spring through fall), contractors can be booked 1 to 3 weeks out. If you're under contract on a home, mention that upfront.

After the system's running, the contractor should do a post-mitigation test -- at least 48 hours, started 24 hours after system activation. Results should show levels below 4.0 and ideally below 2.0.

Long-Term: Keep an Eye on It

Your system includes a visual indicator -- usually a U-tube manometer on the pipe. If the fluid levels are even, the fan's working. If they're flat, the fan probably died and needs replacing.

The EPA recommends retesting every two years, or after any major renovation that changes the building envelope (finishing a basement, replacing windows, adding a room). Continuous radon monitors are also an option if you want ongoing data.

Straight up -- a high radon test isn't the end of the world. It's a fixable problem with a proven solution. The worst thing you can do is nothing.