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: professional 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 a national certification 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.

Build a 14-Day Action Plan So Nothing Gets Missed

A high result feels urgent, so having a simple timeline helps. Day 1 to 2: verify test conditions and record the exact location, dates, and result. Day 3 to 5: collect two to three bids from certified professionals. Day 6 to 10: choose scope, schedule install, and confirm who handles post-mitigation testing. Day 11 to 14: install and run verification.

This process keeps you moving without panic spending. It also protects you in real-estate negotiations because you can show objective steps instead of vague promises. If you are on a contract deadline, tell contractors your closing date first; availability is often the bottleneck, not installation time.

For local context, compare risk and contractor depth in Colorado, Illinois, or your own state page before booking.

How to Talk About Radon With Family, Buyers, or Sellers

Radon conversations go better when you stick to numbers and next steps. Explain that EPA action level is 4.0 pCi/L, average indoor level is about 1.3 pCi/L, and average outdoor level is around 0.4 pCi/L. Then explain the plan to reduce exposure. Clear data lowers anxiety.

If you are buying, ask for one of two structures: seller installs a system before closing with post-test proof, or seller provides a credit large enough to cover full mitigation and verification. Credits should reflect realistic scope, not a guess. In many markets, a practical planning range is roughly $1,200 to $2,500 for standard residential work.

If you are selling, providing a complete mitigation package can protect deal velocity. Buyers are more comfortable when they see scope details, fan information, and a clean post-install test result in writing.

What Numbers to Track After the System Is Installed

Do not stop at a single passing result. Track three things over time: post-install test value, seasonal follow-up value, and system operation indicator status. If you use a continuous monitor, watch trend direction rather than reacting to one-day spikes.

Aim for consistency below 4.0 pCi/L, and many households target closer to 2.0 pCi/L where feasible. WHO guidance references a lower action point around 100 Bq/m3 (about 2.7 pCi/L), which is one reason homeowners often choose stronger initial scope in higher-risk regions.

Use Understand Your Results to interpret follow-up readings, then schedule retesting every two years or after major renovations that change airflow or foundation conditions.

Decision Framework 1 for high radon test result what to do

Homeowners usually get the best outcome when they convert this topic into a step-by-step decision process instead of one big yes-or-no choice. Start with your measured result, confirm testing quality, and then compare options using written scope so every bid can be evaluated fairly.

Use local context to make your plan realistic. Review your state page at state market context, check a comparable city page like local provider depth, and run numbers in the mitigation cost tool. This three-point check helps you avoid overpaying or under-scoping the work.

Technical detail matters here: EPA action level is 4.0 pCi/L, average indoor concentration in U.S. homes is about 1.3 pCi/L, and outdoor background is around 0.4 pCi/L. WHO has also referenced a lower target level near 100 Bq/m3 (about 2.7 pCi/L). Using those benchmarks keeps decisions concrete and consumer-focused.

After you choose a certified professional, set a follow-up testing date immediately. That simple scheduling step is one of the easiest ways to ensure this project actually reduces long-term exposure instead of becoming another unfinished home task.

FAQ

Is 5.0 pCi/L an emergency?

It calls for action, but it is not usually a same-day emergency. Radon risk is tied to sustained exposure over time, so act promptly and methodically.

Should I move out while waiting for mitigation?

Most households stay in place while arranging work. If readings are very high and a delay is unavoidable, discuss temporary exposure-reduction steps with a qualified professional.

Will mitigation fix upper floors too?

Yes. Radon enters at lower levels first, so controlling entry near the foundation generally lowers readings across the home.

Do I still need to retest if the post-test passes?

Yes. Retesting verifies long-term performance and catches fan or pressure issues before exposure builds again.

Final Planning Checklist for This Topic

If you want one simple approach, do this in order: confirm your latest test quality, compare local options with written scope, choose a certified professional based on outcome plan, and document follow-up testing dates now. This keeps decisions clear and reduces expensive backtracking.

Most homeowners get better results when they set a target outcome before comparing bids. For example, they decide they want a stable long-term result well below 4.0 pCi/L, then ask each contractor to explain how their plan gets there. That shifts the conversation from sales language to measurable performance.

Use your local directories and tools together: review state-level context at Pennsylvania or Colorado, check a comparable city like Anchorage, and run numbers in the mitigation cost tool. Keeping all three views aligned makes your final choice faster and more confident.