Why Summer Is the Best Time to Test for Radon (and Fix It)

Most homeowners assume radon is a winter problem. After all, it sounds like the kind of invisible danger that lurks in cold, sealed-up basements during the dark months of the year. So when summer arrives and you crack the windows to let in the breeze, it's tempting to put radon testing on the back burner.

Here's the truth: radon doesn't take a summer vacation — and if you have central air conditioning, summer may actually be the *best* time of year to test and fix it.

Radon Doesn't Drop in Summer

Radon is a naturally occurring radioactive gas that seeps up from uranium in the soil beneath your home. It enters through cracks in your foundation, gaps around pipes, and other openings — year-round, regardless of the season or the temperature outside.

In fact, the EPA and the National Radon Program Services both recommend testing any time of year. The gas is always present. What changes is how well it gets trapped inside your home.

Why Closed Windows Mean More Accurate Results

Here's the counterintuitive part: a *more closed-up* home produces a more accurate radon test. That's because radon accumulates when air circulation is limited. Open windows dilute the gas and can make a dangerous home look safe on paper.

In winter, most homeowners keep their homes sealed to conserve heat — which is one reason winter testing is often recommended. But summer air conditioning changes the equation: when you're running the AC, your windows and doors stay closed for hours at a stretch. Your home becomes nearly as sealed as it is in January.

That means a summer radon test, conducted while your AC is running and your home is closed up, can be just as accurate as a winter test — and far more convenient for scheduling mitigation work.

Summer Is Ideal for Mitigation Installation

If your test comes back elevated (the EPA action level is 4 pCi/L), summer is arguably the best season to get the fix done. Here's why:

• Mitigators have more scheduling flexibility. Demand spikes in late fall and winter when homeowners panic after testing during the heating season. Summer bookings are often easier to land.
• Crews work comfortably. Installing a sub-slab depressurization system involves drilling through your foundation and routing PVC piping to the exterior. It's easier work in dry, warm weather.
• You see results before winter. Getting your system installed in July means you go into the heating season — when radon risk tends to peak — already protected.

Certification Matters: Look for NRPP or NRSB

Not every radon contractor is the same. Before hiring anyone to test or mitigate your home, confirm they hold active certification from one of two nationally recognized credentialing bodies:

• NRPP (National Radon Proficiency Program) — administered by the AARST Consortium on National Radon Standards
• NRSB (National Radon Safety Board)

These certifications require contractors to complete training, pass exams, and stay current with continuing education. An uncertified contractor may install a system that doesn't reduce radon to safe levels — or that doesn't work at all. Always ask for their certification number and verify it before signing a contract.

Find a Certified Mitigator Near You

RadonBase is a free directory of NRPP- and NRSB-certified radon mitigators across the country. Search by state to find vetted professionals in your area, compare credentials, and get quotes.

Don't wait until the windows close for winter. This summer, test your home and — if needed — get the problem fixed before the cold season arrives.

Find a certified radon mitigator near you →