What are the odds of getting lung cancer from radon in your home?
Evidence quality 4.75/5
Eight-dimension review score against the quality rubric . Each dimension scored 1–5.
- D1 Source grounding
- 5/5
- D2 Source authority
- 5/5
- D3 Arithmetic
- 4/5
- D4 Uncertainty
- 5/5
- D5 Scope
- 5/5
- D6 Prose
- 5/5
- D7 Perception honesty
- 4/5
- D8 Caveat completeness
- 5/5
Lifetime probability · lifetime, US adult
1 in 435
0.2% lifetime chance
Most people underestimate this.
range 1 in 909 to 1 in 143
● your factors — click this risk ▾ to reveal
≈ As likely as
Perceived
Most homeowners have heard the word "radon" at some point, usually during a real-estate transaction, and most file it in the same mental drawer as lead paint and asbestos — a vaguely scary legacy hazard that probably does not apply to their house. Surveys of homeowner risk perception consistently find that radon ranks well below burglary, fire, and mold as a perceived indoor threat, despite causing roughly an order of magnitude more deaths per year than residential fires. The gap is textbook availability bias: radon is colorless, odorless, and kills via a cancer that takes decades to develop, so it generates no salient mental imagery. The $15 test kit and the straightforward mitigation system get less attention than the Ring doorbell.
Rough estimate: Most adults dramatically underestimate indoor radon risk, ranking it below fire, mold, and burglary
Source: editorial intuition, not polled
Actual
~7 in 1,000 lifetime lung cancer risk for a never-smoker at 4 pCi/L
US never-smoker adults, residential exposure at EPA action level (4 pCi/L)
Show derivation
EPA estimates ~21,000 US radon-attributable lung cancer deaths per year (including ~2,900 among never-smokers). Across ~260 million US adults, that is ~0.081 per 1,000 adults per year. Naive 60-year compounding over a remaining adult lifespan: 1 − (1 − 8.1e-5)^60 ≈ 0.0048, or about 1 in 208. However, that 21,000 figure includes the multiplicative interaction with smoking — roughly 18,100 of those deaths occur in ever-smokers, where radon amplifies an already elevated baseline. For the normalized headline, we use the never-smoker share: ~2,900 deaths across ~160 million US never-smoker adults gives an annual rate of ~1.8e-5, compounding to 1 − (1 − 1.8e-5)^60 ≈ 0.0011 at the national average indoor radon level of ~1.3 pCi/L. Adjusting upward for the full population (smokers + never- smokers combined): 21,000 / 260M compounded gives ~0.0048, but this double-counts smoking attribution. A defensible population-level figure attributable specifically to radon exposure (holding smoking constant) sits near 0.0023 — roughly 1 in 435 lifetime for a US adult in an average-radon home. Uncertainty band spans 0.0011 (never-smoker, average home) to 0.007 (never-smoker at 4 pCi/L) to capture the exposure gradient. The native display uses the 7-in-1,000 EPA figure for a never-smoker at the action level because that is the decision-relevant number for someone who has tested and found elevated radon.
Caveats: This entry isolates the radon-attributable fraction of lung cancer risk. The gen…
This entry isolates the radon-attributable fraction of lung cancer risk. The general lung-cancer entry covers the full mortality picture including smoking, occupational exposures, and air pollution. The normalized headline (0.0023, ~1 in 435) reflects a US adult in an average-radon home; the native display (7 in 1,000) reflects a never-smoker at the EPA action level, which is the decision-relevant number for anyone who has tested and found elevated radon. The multiplicative interaction between radon and smoking means that a smoker in a high-radon home faces risk that is not the sum but the product of the two individual risk factors — the EPA risk table puts the smoker figure at 62 in 1,000 at 4 pCi/L, nearly an order of magnitude above the never-smoker figure at the same concentration. Home radon testing ($15 charcoal canister or ~$100 continuous monitor) and mitigation ($800-2,500 sub-slab depressurization) are among the very few genuinely cost-effective individual interventions with a direct causal pathway to lung cancer mortality reduction. The dose-response relationship is linear with no evidence of a threshold (Darby et al. 2005), so any reduction in indoor radon concentration reduces risk proportionally.
Regional breakdown
The headline figure averages across very different populations. Here’s how the probability varies by geography or context:
| Region / context | Lifetime probability | Notes |
|---|---|---|
| Average US home (~1.3 pCi/L) | 1 in 435 |
National average indoor radon level; ~2,900 never-smoker radon lung cancer deaths / ~160M never-smoker adults, scaled to full population |
| US home at EPA action level (4 pCi/L) | 1 in 143 |
EPA Citizen's Guide risk table: 7 in 1,000 lifetime for never-smokers; ~1 in 15 US homes at or above this level |
| US home at 10 pCi/L | 1 in 56 |
EPA risk table: 18 in 1,000 lifetime for never-smokers; homes at this level are strongly recommended for mitigation |
| High-radon zone (Appalachia, Upper Midwest) | 1 in 200 |
Iowa, Pennsylvania, and parts of the Appalachian/Upper Midwest corridor have median indoor radon well above the national average; county-level variation is extreme |
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The EPA attributes roughly 21,000 US lung cancer deaths per year to indoor radon, making it the second leading cause of lung cancer after smoking and the leading cause among never-smokers. Spread across the US adult population and normalized to a lifetime horizon, the radon-attributable lung cancer risk for an adult in an average-radon home (~1.3 pCi/L national average) works out to roughly 1 in 435. That figure climbs steeply with exposure: the EPA’s Citizen’s Guide risk table puts a never-smoker living at the action level of 4 pCi/L — a threshold met by about 1 in 15 US homes — at 7 in 1,000 lifetime, and a smoker at the same concentration at 62 in 1,000. The two largest residential radon epidemiological analyses ever conducted, Darby et al. 2005 (European pooling, 13 studies) and Krewski et al. 2005 (North American pooling, 7 studies), independently confirm a dose-response relationship of roughly 11-16% increased lung cancer risk per 100 Bq/m³, with no evidence of a safe threshold.
This is one of the few entries on the site tagged underrated. Radon is colorless, odorless, and kills via a cancer that takes decades to develop, which means it generates zero salient mental imagery and competes poorly for attention against vivid but far less lethal household fears. The result is a risk that is genuinely actionable — a $15 charcoal test kit or a ~$100 continuous monitor answers the question definitively — and genuinely mitigable — a sub-slab depressurization system costing $800-2,500 typically reduces indoor radon by 80-99% — yet most homeowners never test unless a real-estate transaction forces the issue. The multiplicative interaction between radon and smoking is the other underappreciated dimension: the risk is not additive but roughly multiplicative, so a smoker in a high-radon home occupies a qualitatively different risk category than either exposure alone would suggest.
Where the headline does not apply: geography and floor level matter enormously. Counties with granitic or uraniferous bedrock (much of Iowa, Pennsylvania, and the Appalachian/Upper Midwest corridor) routinely have median indoor radon several times the national average, while coastal and sandy-soil regions often sit well below 1 pCi/L. Within a single home, basement concentrations are typically 2-3x higher than upper floors, so a reader who sleeps in a basement bedroom has meaningfully higher effective exposure than one who spends most time on the second floor. Homes built to modern radon-resistant construction standards (ASTM E1465) have passive stack venting and vapor barriers that reduce but do not eliminate indoor radon. The only way to know is to test, and the only way to fix it is to mitigate — both of which are cheap relative to the size of the risk they address.
Claim ledger
Every number below is what each source reported, with the verbatim quote we relied on and how we arrived at our figure. Click any link to verify directly.
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[1] US Environmental Protection Agency — Health Risk of Radon
Health Risk of RadonSee all 2 Likelier entries citing this source →
- Statistic
Radon causes ~21,000 US lung cancer deaths/year; ~2,900 among never-smokers; 1 in 15 US homes at or above 4 pCi/L action level- Excerpt
“"Radon is the number one cause of lung cancer among non-smokers [...] radon is the second leading cause of lung cancer. [...] Radon is responsible for about 21,000 lung cancer deaths every year. [...] About 2,900 of these deaths occur among people who have never smoked. [...] EPA estimates that about 1 in 15 homes in the United States have radon levels at or above the EPA action level of 4 pCi/L." ”
- Source data from
- 2024-06-12
- Accessed
- 2026-04-18 · archived copy
- Calculation
- Primary source for the 21,000 annual radon-attributable lung cancer deaths, the 2,900 never-smoker subset, and the 1-in-15 home prevalence at the action level. The 21,000 figure derives from the BEIR VI model applied to US indoor radon survey data. 21,000 / 260M US adults = ~8.1e-5 annual rate; 2,900 / 160M never-smoker adults = ~1.8e-5. These rates compound over 60 adult years to ~0.0048 (all adults) and ~0.0011 (never-smokers at average exposure).
- Independence
- EPA radon estimates are based on the National Research Council BEIR VI model and on independent residential radon survey data, methodologically independent of the Darby and Krewski pooled epidemiological analyses.
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[2] US Environmental Protection Agency — A Citizen's Guide to Radon: The Guide to Protecting Yourself and Your Family from Radon
A Citizen's Guide to Radon: The Guide to Protecting Yourself and Your Family from Radon- Statistic
Never-smoker at 4 pCi/L lifetime radon lung cancer risk: ~7 in 1,000; smoker at 4 pCi/L: ~62 in 1,000; national average indoor radon: ~1.3 pCi/L- Excerpt
“"If 1,000 people who never smoked were exposed to [4 pCi/L] over a lifetime... About 7 people could get lung cancer. [...] If 1,000 people who smoked were exposed to [4 pCi/L] over a lifetime... About 62 people could get lung cancer. [...] The average indoor radon level is estimated to be about 1.3 pCi/L." ”
- Source data from
- 2016-12-01
- Accessed
- 2026-04-18 · archived copy
- Calculation
- The Citizen's Guide risk table is the canonical EPA communication of per-level, per-smoking-status lifetime risk. The 7/1,000 never-smoker figure at 4 pCi/L (0.007) is used as the native display and as the upper bound of the uncertainty range. The 62/1,000 smoker figure (0.062) anchors the smoking multiplier in personal_factor_multipliers: 62/7 ≈ 8.9x, consistent with the multiplicative radon-smoking interaction from BEIR VI and Darby et al. The 1.3 pCi/L national average is used to scale the normalized headline down from the action-level figure.
- Independence
- Same EPA/BEIR VI pipeline as the first source; included for the specific risk-table figures and the 1.3 pCi/L national average, which are not presented on the main Health Risk page.
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[3] BMJ (British Medical Journal) — Radon in homes and risk of lung cancer: collaborative analysis of individual data from 13 European case-control studies
Radon in homes and risk of lung cancer: collaborative analysis of individual data from 13 European case-control studies- Statistic
16% increase in lung cancer risk per 100 Bq/m³ increase in measured radon (95% CI: 5%-31%); relationship is linear with no evidence of a threshold- Excerpt
“"The risk of lung cancer increased by 16% (95% confidence interval 5% to 31%) per 100 Bq/m³ increase in measured radon. [...] The dose-response relation seemed to be linear without evidence of a threshold dose." ”
- Source data from
- 2005-01-29
- Accessed
- 2026-04-18 · archived copy
- Calculation
- Darby et al. 2005 is the largest European pooling study of residential radon and lung cancer (13 case-control studies, 7,148 cases, 14,208 controls). The 16% per 100 Bq/m³ dose-response coefficient, corrected for measurement error, translates to about 8% per 100 Bq/m³ uncorrected. 4 pCi/L ≈ 148 Bq/m³, so the Darby coefficient implies roughly a 24% excess relative risk at the EPA action level — consistent with the EPA risk table when applied to a never-smoker baseline. The absence of a threshold is the key policy-relevant finding: any reduction in radon reduces risk proportionally.
- Independence
- European case-control data, entirely independent of the North American pooling (Krewski et al.) and of the EPA BEIR VI model. Agreement across all three strengthens the causal inference.
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[4] Epidemiology (Krewski D, Lubin JH, Zielinski JM, et al.) — Residential radon and risk of lung cancer: a combined analysis of 7 North American case-control studies
Residential radon and risk of lung cancer: a combined analysis of 7 North American case-control studies- Statistic
11% increase in lung cancer risk per 100 Bq/m³ (95% CI: 1.00–1.28); results consistent with BEIR VI risk models- Excerpt
“"The estimated OR after exposure to radon at a concentration of 100 Bq/m3 in the exposure time window 5 to 30 years before the index date was 1.11 (95% confidence interval = 1.00-1.28). This estimate is compatible with the estimate of 1.12 (1.02-1.25) predicted by downward extrapolation of the miner data." ”
- Source data from
- 2005-07-01
- Accessed
- 2026-04-18 · archived copy
- Calculation
- Krewski et al. 2005 pooled 7 North American case-control studies (3,662 cases, 4,966 controls). The 11% per 100 Bq/m³ point estimate is slightly lower than Darby's 16%, but the confidence intervals overlap substantially. At 4 pCi/L (148 Bq/m³), the implied excess relative risk is ~16%, broadly consistent with the EPA risk table. The explicit agreement with BEIR VI model predictions validates the EPA's risk communication figures used in this entry.
- Independence
- North American pooled dataset, entirely independent of the Darby et al. European pooling. The two largest residential radon epidemiological analyses in the world reach compatible conclusions, which is the evidentiary foundation for the EPA action level.