A compiled reference of 20 verified statistics on radon in US homes, from how many homes carry elevated levels and why radon is a leading cause of lung cancer, to what testing and a mitigation system actually cost. Every figure is drawn from a named public source (the US Environmental Protection Agency, the World Health Organization, and HomeAdvisor) and independently checked against the original before publishing.
Key statistics
5 highlights from this report
Key statistics
Key takeaways
Radon is a common, invisible, and deadly home hazard with a cheap fix: it is present in roughly one in fifteen homes, it kills more Americans a year than drunk driving, and a system that removes almost all of it costs about the same as a mid-range appliance.
Nearly 1 in 15 US homes has elevated radon (4 pCi/L or higher).
Radon causes about 21,000 US lung cancer deaths a year, #1 among non-smokers.
A radon mitigation system averages about $1,028 ($786 to $1,274).
The WHO attributes 3% to 14% of all lung cancers to radon.
Radon reduction systems can cut a home's radon level by up to 99%.
How we built this report
Every figure below was compiled in September 2026 from named public sources and checked against the original document before publishing.
- Compiled from primary sources
US EPA radon guidance (A Citizen's Guide to Radon, the Health Risk of Radon pages, and the Surgeon General's advisory), the World Health Organization's radon fact sheet, and national cost data.
- Only explicitly stated figures
We include only numbers a named source states directly, and attribute each inline at the point it appears.
- Units kept as published
US sources use pCi/L and the WHO uses Bq/m3; we report each figure in the unit its source used rather than converting and introducing rounding error.
- Independent review
Written by one co-founder and reviewed by the other before publishing.
Scope note: prevalence and health figures are EPA and WHO estimates; radon varies widely by geology, home, and season, so only a test of your specific home tells you its level. Cost figures are guide-level national ranges and vary by home size and method. Confirm any single figure against the specific source before relying on it.
Radon, by the numbers
All 20 figures, grouped into four themes: how common radon is, the health risk, what mitigation costs, and testing and system economics. Each is drawn from a named public source and independently verified.
How common elevated radon is
Radon is not a rare or regional problem. According to the US Environmental Protection Agency (epa.gov), nearly 1 out of every 15 homes in the US is estimated to have elevated radon, the gas is found in all 50 states, and any home, new or old, with or without a basement, can have it. The average indoor level is 1.3 pCi/L against 0.4 pCi/L outdoors, and the EPA sets its action level at 4 pCi/L while stressing that levels below 4 still carry risk. The World Health Organization (who.int) recommends a reference level of 100 Bq/m3, and no more than 300 Bq/m3.
Statistic 1
Nearly 1 out of every 15 US homes is estimated to have elevated radon levels (at or above 4 pCi/L).
US EPA, A Citizen's Guide to Radon
Statistic 2
Radon is found in all 50 states, comes from the natural decay of uranium in soil, and can occur in any home.
US EPA
Statistic 3
The average indoor radon level is about 1.3 pCi/L, versus 0.4 pCi/L outdoors.
US EPA
Statistic 4
The EPA action level is 4 pCi/L, but there is no known safe level; levels below 4 still pose a risk.
US EPA
Statistic 5
The WHO recommends a radon reference level of 100 Bq/m3 where feasible, not to exceed 300 Bq/m3.
World Health Organization
What this means: Because radon is invisible, odorless, and possible in any home in any state, the only way to know a home's level is a test, which is why radon testing is a standard part of a home inspection and a common contingency in a real-estate transaction.
The health risk
The reason radon testing exists is a serious, well-documented cancer risk. According to the US EPA (epa.gov), radon causes about 21,000 lung cancer deaths a year in the US, making it the second leading cause of lung cancer overall and, per EPA and Surgeon General estimates, the number one cause among non-smokers. That death toll exceeds drunk driving, home falls, drownings, and home fires, as the comparison below shows. The World Health Organization (who.int) attributes 3% to 14% of all lung cancers in a country to radon, and finds lung cancer risk rises about 16% per 100 Bq/m3 of long-term radon exposure.
Statistic 6
Radon causes about 21,000 lung cancer deaths a year in the US.
US EPA
Statistic 7
Radon is the second leading cause of lung cancer overall and the number one cause among non-smokers.
US EPA and the US Surgeon General
Statistic 8
Radon's US death toll (21,000) exceeds drunk driving (17,400), falls in the home (8,000), drownings (3,900), and home fires (2,800).
US EPA (citing CDC and National Safety Council)
Statistic 9
The WHO attributes 3% to 14% of all lung cancers in a country to radon, depending on average levels and smoking rates.
World Health Organization
Statistic 10
Lung cancer risk rises about 16% per 100 Bq/m3 increase in long-term radon exposure.
World Health Organization
Statistic 11
A lifelong smoker exposed to 4 pCi/L faces about 62 lung-cancer deaths per 1,000, versus 7.3 per 1,000 for people who never smoked.
US EPA
What this means: Radon and smoking multiply each other's risk, so the hazard is worst in exactly the homes where a smoker is present, but the 7.3-per-1,000 figure for never-smokers is why the EPA recommends every home be tested regardless.
What mitigation costs
The fix is comparatively cheap for the risk it removes. According to HomeAdvisor (homeadvisor.com), a radon mitigation system averages $1,028, with most homeowners spending $786 to $1,274; small homes can run as little as $395 and large or complex jobs up to about $2,453. Cost tracks the method: the workhorse active sub-slab suction system runs $1,000 to $3,000, a passive depressurization system $500 to $2,500, and radon-in-water mitigation $1,200 to $5,000. And per the EPA (epa.gov), those systems can lower a home's radon by up to 99%.
Statistic 12
A radon mitigation system averages $1,028, with most homeowners spending $786 to $1,274.
HomeAdvisor (2026)
Statistic 13
Small homes can be mitigated for as little as $395; large or complex jobs run up to about $2,453.
HomeAdvisor (2026)
Statistic 14
By method: active sub-slab suction $1,000 to $3,000, passive depressurization $500 to $2,500, radon-in-water mitigation $1,200 to $5,000.
HomeAdvisor (2026)
Statistic 15
Radon reduction systems can lower a home's radon level by up to 99%.
US EPA
Statistic 16
Encapsulating a crawl space, sometimes part of a radon fix, costs $1,500 to $15,000.
HomeAdvisor (2026)
What this means: At roughly $1,000 for a system that removes almost all of a Class-A carcinogen, radon mitigation is one of the highest-value repairs in home ownership, and far cheaper than the structural repairs elsewhere in this research library.
Testing and system economics
Testing comes first and costs little. According to HomeAdvisor (homeadvisor.com), a professional radon test runs $150 to $800 and permits add $25 to $150, though low-cost DIY test kits are widely available. The EPA (epa.gov) and the Surgeon General recommend testing all homes below the third floor, and retesting after any mitigation. Once a system is in, the ongoing cost is modest: a radon fan uses 300 to 3,000 kWh a year (about $30 to $300 on the energy bill), active systems last 10 to 30 years, and fans are typically replaced every 5 to 10 years.
Statistic 17
A professional radon test costs $150 to $800; permits add $25 to $150.
HomeAdvisor (2026)
Statistic 18
The EPA and Surgeon General recommend testing all homes below the third floor, and retesting after mitigation.
US EPA and the US Surgeon General
Statistic 19
A radon fan uses 300 to 3,000 kWh a year, adding about $30 to $300 to the annual energy bill.
HomeAdvisor (2026)
Statistic 20
Active radon systems last 10 to 30 years; fans are typically replaced every 5 to 10 years.
HomeAdvisor (2026)
What this means: A one-time test in the low hundreds of dollars is the gate to the whole decision. Because radon can be introduced or worsened by foundation cracks and settlement, a radon test pairs naturally with a foundation condition check at purchase.
Cite this study
Academic or press use: copy a ready-made reference. RapidEye is the publisher.
Quick FAQ
How common is elevated radon in US homes?
Nearly 1 in 15 US homes is estimated to have radon levels at or above the EPA action level of 4 pCi/L, according to the US EPA (epa.gov). Radon is found in all 50 states and can occur in any home, new or old.
How much does radon mitigation cost?
A radon mitigation system averages about $1,028, with most homeowners spending $786 to $1,274, according to HomeAdvisor (homeadvisor.com). Small homes can run as little as $395 and large or complex jobs up to about $2,453, plus $150 to $800 for testing.
How dangerous is radon?
Radon causes about 21,000 lung cancer deaths a year in the US, the second leading cause of lung cancer overall and the number one cause among non-smokers, according to the US EPA (epa.gov). The World Health Organization (who.int) attributes 3% to 14% of all lung cancers to radon.
What radon level requires action?
The EPA (epa.gov) recommends fixing a home when the radon level is 4 pCi/L or higher, though levels below 4 still pose a risk. The World Health Organization (who.int) recommends a reference level of 100 Bq/m3, not to exceed 300 Bq/m3.
Data sources
Every figure traces to one of these named public sources, each checked against the original before publishing. We name each source and show its root domain, but do not link out: it keeps this reference the terminal citation. Internal links stay live.
US Environmental Protection AgencyA Citizen's Guide to Radon and radon health-risk pagesepa.gov
World Health OrganizationRadon and health fact sheetwho.int
HomeAdvisorRadon mitigation cost datahomeadvisor.com