Radon Tester vs. Mitigator: What's the Difference?

Two Jobs, Two Certifications

When you search for a "radon professional," you'll find two distinct types — and hiring the wrong one is a frustrating and expensive mistake.

Radon Tester

A certified radon tester is trained to measure radon levels in a home. They place charcoal canisters or electronic monitors, collect samples following EPA protocols, and provide a test report with results. That's their scope.

They are not certified to design or install mitigation systems — and in most states, they're not allowed to do so.

Radon Mitigator

A certified radon mitigator is trained to fix elevated radon levels. They assess your home's foundation, design a system, install the fan and piping, and verify the result drops below safe levels.

Most mitigators are not certified testers — they subcontract testing or refer you to a separate tester for the initial measurement.

Why Most Directories Get This Wrong

Angi, HomeAdvisor, Thumbtack, and even state health department directories often list "radon professionals" without distinguishing between testers and mitigators. You call who's at the top of the list, and you may end up talking to someone who can only tell you the problem — not fix it.

If you already have test results above 4 pCi/L, you don't need a tester. You need a mitigator.

RadonBase lists only certified mitigators — every professional in our directory can actually fix your radon problem.

One Contractor, Two Hats

Some contractors hold both certifications — they can test and mitigate. This sounds convenient but has a built-in conflict of interest: the same contractor who runs your test also profits from the mitigation job.

Most states with strict radon programs (Minnesota, Iowa, Illinois) discourage or prohibit the same contractor from both testing and mitigating the same home for this reason. An independent test gives you an unbiased baseline.

If you haven't tested yet: buy a $17 short-term charcoal kit from a certified lab (see our shop), get your result, then look for a mitigator if levels are high.

The Two National Certification Bodies

Both the NRPP and NRSB are recognized by the EPA, but they're separate organizations with separate exams.

NRPP (National Radon Proficiency Program)

• Largest certification body in the US
• Verify at: radonproficiency.org
• Issues separate certifications for testing and mitigation

NRSB (National Radon Safety Board)

• Smaller, primarily East Coast focus
• Verify at: nrsb.org
• Also issues separate testing and mitigation credentials

Both require passing an exam, field experience, and continuing education to maintain certification. A valid certification number and current status means the contractor has met these requirements.

How to Check Before You Hire

1. Ask for the contractor's certification number and which body (NRPP or NRSB)
2. Go to radonproficiency.org or nrsb.org and search for them
3. Confirm their certification is current (not expired)
4. Confirm it's for mitigation — not just testing

If a contractor won't provide a certification number, don't hire them. All RadonBase listings are pre-verified against both databases before being published.

Find a certified mitigator in your state →