Radon Statistics & Facts
Radon is the second leading cause of lung cancer in the United States. These statistics, sourced from the EPA, WHO, and American Cancer Society, help homeowners understand the scope of radon risk.
21,000
Lung cancer deaths per year attributed to radon in the U.S.
Source: EPA
1 in 15
U.S. homes estimated to have radon above the EPA action level
Source: EPA
4.0 pCi/L
EPA recommended action level for radon mitigation
Source: EPA
148 Bq/m³
WHO recommended reference level for indoor radon
Source: WHO
EPA Radon Zones
The EPA divides the U.S. into three radon zones based on predicted average indoor screening levels. Zone 1 counties have the highest predicted radon levels.
Zone 1 — High
Predicted average indoor level > 4 pCi/L
States with significant Zone 1 areas: Iowa, North Dakota, Colorado, Minnesota, Pennsylvania, Ohio, Indiana, Nebraska, Montana.
Zone 2 — Moderate
Predicted average indoor level 2–4 pCi/L
Many states have a mix of Zone 1 and 2 counties. Testing is recommended in all Zone 2 areas.
Zone 3 — Low
Predicted average indoor level < 2 pCi/L
Lower predicted levels, but elevated radon can occur in any zone. The EPA recommends testing every home regardless of zone.
Health Impact
Radon and Lung Cancer
- Radon is the #1 cause of lung cancer among non-smokers and the #2 cause overall (after smoking).
- An estimated 21,000 lung cancer deaths per year in the U.S. are attributed to radon exposure (EPA).
- Smokers exposed to elevated radon face a significantly higher combined risk — up to 10x greater than non-smokers.
- There are no immediate symptoms of radon exposure. Lung cancer from radon typically develops after 5–25 years of exposure.
- The WHO classifies radon as a Group 1 carcinogen (confirmed human carcinogen).
Testing & Mitigation
Testing Facts
- Short-term radon tests take 2–7 days; long-term tests run 90+ days.
- DIY test kits cost $10–$40; professional testing runs $125–$275.
- The EPA recommends testing every home below the 3rd floor.
- Homes should be retested every 2 years or after major renovations.
Mitigation Facts
- Active soil depressurization (ASD) systems reduce radon by up to 99%.
- Average residential mitigation cost: $1,000–$3,000 depending on home size and foundation type.
- Installation typically takes 4–8 hours for standard homes.
- Mitigation systems use about $3–$8/month in electricity (equivalent to a lightbulb).
- Radon mitigation can increase home value and is often required for real estate transactions.
High-Risk States
Some states have a higher proportion of homes with elevated radon. These states have extensive Zone 1 coverage and higher average indoor levels.
Sources
- U.S. Environmental Protection Agency (EPA) — "A Citizen's Guide to Radon"
- EPA — "EPA Map of Radon Zones"
- World Health Organization (WHO) — "WHO Handbook on Indoor Radon"
- American Cancer Society — "Radon and Cancer"
- National Radon Proficiency Program (NRPP)
- National Radon Safety Board (NRSB)
Statistics reflect the most current publicly available data. See our methodology for how we source and verify information.
Reviewed by
FindRadonPros Editorial Team
Our editorial team consults with NRPP- and NRSB-certified radon professionals to ensure accuracy. Content is reviewed against EPA guidelines and updated regularly as standards evolve.
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