How To Choose a Certified Radon Tester
Why Certification Matters
Radon testing sounds simple, but the accuracy of results depends heavily on proper device placement, calibration, test conditions, and lab analysis. A tester without proper training and equipment can return results that are inaccurate — leaving you with a false sense of security or triggering unnecessary mitigation costs.
Most states recommend or require that radon measurement professionals hold a recognized certification. Even in states without mandatory licensing, hiring a certified tester is the industry standard — and the only approach accepted for real estate transactions by most buyers, sellers, and lenders.
NRPP vs AARST-NRSD: The Two Main Certifying Bodies
NRPP
National Radon Proficiency Program — operated by the National Radon Safety Board (NRSB). One of the two nationally recognized radon certification programs accepted by the EPA and most state agencies.
Look for the credential: RMP (Radon Measurement Provider) or RMRS (Radon Measurement Residential Specialist).
AARST-NRSD
American Association of Radon Scientists and Technologists — National Radon Standards Development. AARST certifies radon measurement and mitigation professionals and develops industry standards adopted by the EPA.
AARST-certified professionals have completed training and passed standardized examinations covering radon measurement methodology and device use.
Both NRPP and AARST-NRSD certifications are nationally recognized. Either is acceptable for real estate and residential testing. You can verify a tester's certification directly on the NRSB or AARST websites using their certification number.
Typical Cost Ranges
Professional radon testing costs vary by region, test type, and what's included:
| Service | Typical Range |
|---|---|
| Short-term professional test (2–4 days) | $100–$200 |
| Continuous monitor test (48–72 hrs) | $150–$300 |
| Real estate transaction test | $150–$300 |
| Multiple areas / large home | Add $50–$100 per additional area |
Questions to Ask Before Hiring
- ✓Do you hold a current NRPP or AARST-NRSD certification?
- ✓Can you provide your certification number so I can verify it?
- ✓Do you carry errors and omissions (E&O) and general liability insurance?
- ✓What type of device do you use — continuous monitor or passive?
- ✓Are your monitors calibrated? When were they last calibrated?
- ✓How will you deliver results — written report or digital?
- ✓Do you provide a copy of the test report for my records?
- ✓If the test is for a real estate transaction, can you meet the deadline?
- ✓What is your total cost, including the lab fee if applicable?
Red Flags to Watch For
- ✗No certification or unwilling to provide their certification number
- ✗Uses devices that have not been calibrated
- ✗Offers to do testing and mitigation in the same transaction without independent verification
- ✗Refuses to provide a written report
- ✗Very low price with no explanation (may use unaccredited lab or uncalibrated device)
- ✗Cannot name their certifying organization
- ✗Offers to "guarantee" a specific result before testing
Real Estate Transactions: Extra Considerations
If you need a radon test as part of a home purchase or sale, there are additional factors to consider:
- The tester must be independent — neither buyer's nor seller's agent should have a financial interest in the result
- Most lenders and buyers require a continuous electronic monitor (not a passive kit) for real estate tests
- Results must typically be delivered within 24 hours of test completion
- The test must be conducted under closed-house conditions (windows and doors closed)
- Confirm that your tester can meet the inspection contingency deadline