Radon in United States
Official radon data, regulations and resources
National reference level
148 Bq/m³
Competent authority
What should you do?
Regardless of the official classification, the only way to know the radon level in a specific building is to measure it. A long-term test (at least 3 months) is recommended. You can either test yourself with passive detectors or hire a certified professional.
Regulations & obligations
Dwellings
Action level 4 pCi/L (≈150 Bq/m³) for homes - EPA recommendation (not legally binding federal law). States may have additional requirements.
Workplaces
OSHA Permissible Exposure Limit (PEL): 100 pCi/L (≈3700 Bq/m³) 8-hour time-weighted average for occupational exposure. Significantly higher than residential level.
Professional services
NRPP
NRPP-Certified Professionals
NEHA-administered NRPP certifications (RMP, RMFT, RMS) accredited by ANAB under ANSI/ISO/IEC 17024
Accredited by: NRPP (NEHA)
NRSB
NRSB-Certified Professionals
Independent NRSB certifications (RMT, RMS, RRS, ARL) following ANSI-AARST standards
Accredited by: NRSB
State-Licensed Radon Professionals
State-licensed radon measurement or mitigation professionals (required in ~20 states)
How radon is measured in United States
Each country has its own official measurement protocol. Here is how radon testing works according to the national guidelines.
Measurement method
Short-term (charcoal/electret) or long-term (alpha-track) detectors
Minimum duration
Short-term: 2–90 days; long-term: over 90 days (recommended)
Recommended season
Year-round, closed-building conditions for short-term tests
Detector placement
Lowest liveable level, 20 inches above floor, away from exterior walls, mid-room placement
Laboratory requirements
NRPP or NRSB-listed measurement professional or laboratory
Reference standard: ANSI/AARST MAH, MAMF · EPA Citizen’s Guide; IRAA 1988
How to test for radon yourself
Regardless of where you live, testing for radon is easy and affordable. A long-term measurement with passive detectors is the most reliable way to know your indoor radon level.
Learn how to testMajor Cities
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