Radon Health Risks: Why the #2 Cause of Lung Cancer Is in Your Home
Radon kills more Americans than drunk driving, drowning, and house fires combined. Here's what the science says — and what you can do about it.
The Numbers: How Deadly Is Radon?
Radon is responsible for an estimated 21,000 lung cancer deaths per year in the United States, according to the EPA. That makes it the leading cause of lung cancer among non-smokers and the second leading cause overall, behind only cigarette smoking.
To put that in perspective, consider that lung cancer kills more people than breast cancer, colon cancer, and prostate cancer combined. And radon is a significant contributing factor in a substantial portion of those deaths.
21,000
Radon lung cancer deaths per year
1 in 15
U.S. homes above EPA action level
2,900
Deaths among never-smokers
#1
Cause of lung cancer in non-smokers
These aren't theoretical projections — they're based on extensive epidemiological studies of uranium miners, combined with residential radon studies from North America, Europe, and China. The scientific consensus on radon's carcinogenicity is as strong as it is for asbestos or secondhand smoke. The World Health Organization, the U.S. Surgeon General, the National Academy of Sciences, and the CDC all classify radon as a known human carcinogen.
How Radon Causes Lung Cancer
Radon itself is a noble gas — it doesn't chemically react with your body. The danger comes from its radioactive decay products, known as "radon daughters" or "radon progeny" (primarily polonium-218 and polonium-214). Here's what happens:
Inhalation
You breathe in air containing radon gas and its solid decay products. These microscopic radioactive particles attach to dust and aerosols in your home's air.
Deposition
The radioactive particles become lodged in the lining of your lungs, particularly in the bronchial epithelium — the thin layer of cells lining your airways.
Alpha radiation
As these particles continue to decay, they emit alpha particles — high-energy, high-mass radiation that travels only a short distance but causes intense localized damage.
DNA damage
Alpha particles striking lung cells damage or destroy DNA. While your body can repair some damage, over years of continuous exposure, some cells accumulate mutations that escape repair.
Cancer development
Accumulated DNA damage can cause cells to grow and divide uncontrollably, forming malignant tumors. This process typically takes 5 to 25 years of exposure.
An important nuance: radon-related lung cancer is almost exclusively linked to the lungs. Unlike some environmental carcinogens that affect multiple organ systems, radon's decay products primarily damage the tissue they directly contact — your airway lining. Radon dissolved in water that you drink does not pose a significant cancer risk to the stomach (the risk from water radon comes from the gas released into indoor air during showering and water use).
Radon Risk Compared to Other Hazards
We accept many risks in daily life, often without thinking about them. Radon's risk is real but invisible, which makes it easy to ignore. Here's how it compares to hazards we take more seriously:
| Cause of Death | Annual U.S. Deaths |
|---|---|
| Radon-induced lung cancer | ~21,000 |
| Drunk driving | ~13,000 |
| Falls in the home | ~8,000 |
| Drowning | ~4,000 |
| House fires | ~2,500 |
| Carbon monoxide poisoning | ~430 |
We install smoke detectors, carbon monoxide alarms, and pool fences. We wear seat belts and check for gas leaks. Yet most homes have never been tested for radon — a hazard that kills far more people than many of these combined. The disconnect is largely because radon is invisible and its effects are delayed by years or decades.
Who Is Most at Risk?
Everyone exposed to elevated radon is at increased risk for lung cancer, but certain groups face disproportionately higher danger:
Smokers and former smokers
The combination of smoking and radon exposure is devastating. A smoker exposed to 4 pCi/L of radon has roughly 6 times the lung cancer risk of a non-smoker at the same radon level. If you smoke (or ever smoked) and live in a home with elevated radon, testing and mitigation should be an urgent priority.
Children
Children breathe at a faster rate relative to their body size, potentially receiving a higher dose of radiation per unit of body weight. They also have more years ahead for cancer to develop. While radon-related lung cancer typically appears in adulthood, childhood exposure contributes to lifetime cumulative risk.
People who spend more time at home
Remote workers, stay-at-home parents, retirees, and anyone who spends most of their time indoors accumulates more exposure. If you're home 18+ hours a day instead of 12, your effective radon dose is 50% higher.
People with existing lung conditions
Those with COPD, emphysema, asthma, or other chronic lung diseases may be more vulnerable to the effects of radon exposure, though the research is less definitive for these groups than for smokers.
Radon and Smoking: A Deadly Combination
The interaction between radon and smoking is not simply additive — it's synergistic. This means the combined risk is greater than the sum of each risk individually. Smoking damages the lung's natural defense mechanisms and creates conditions that make radon's alpha radiation even more damaging.
| Radon Level | Never-Smoker Risk | Smoker Risk |
|---|---|---|
| 20 pCi/L | 3.6% lifetime risk | 26% lifetime risk |
| 10 pCi/L | 1.8% lifetime risk | 15% lifetime risk |
| 8 pCi/L | 1.5% lifetime risk | 12% lifetime risk |
| 4 pCi/L (EPA action level) | 0.7% lifetime risk | 6.2% lifetime risk |
| 2 pCi/L | 0.4% lifetime risk | 3.2% lifetime risk |
| 1.3 pCi/L (U.S. average) | 0.2% lifetime risk | 2% lifetime risk |
Source: EPA Assessment of Risks from Radon in Homes (EPA 402-R-03-003)
At the EPA action level of 4 pCi/L, a smoker's lifetime lung cancer risk from radon is approximately 6.2% — nearly 9 times higher than a never-smoker's 0.7% risk at the same level. That 6.2% risk is comparable to dying in a car crash over a lifetime. The message is stark: if you smoke, radon testing and mitigation are even more critical.
Understanding Your Risk Level
The following chart helps you understand what different radon levels mean in terms of comparable risks — the everyday hazards we already take seriously.
20 pCi/L
Non-smoker: ~36 per 1,000 people. Comparable to being a heavy smoker in terms of lung cancer risk alone.
10 pCi/L
Non-smoker: ~18 per 1,000 people. Risk comparable to dying in a car crash. Fix your home.
4 pCi/L (EPA action level)
Non-smoker: ~7 per 1,000 people. Risk comparable to dying from a fall. EPA strongly recommends mitigation.
2 pCi/L (WHO action level)
Non-smoker: ~4 per 1,000 people. Risk comparable to drowning. EPA recommends considering mitigation.
1.3 pCi/L (U.S. average indoor level)
Non-smoker: ~2 per 1,000 people. Average exposure for most Americans. Some risk remains.
Protecting Your Family from Radon
The good news about radon is that it's one of the most preventable causes of cancer. Unlike many environmental hazards, radon can be effectively measured and dramatically reduced with proven technology. Here's what you should do:
Test your home
Every home should be tested. DIY kits cost $10–$50 and take minutes to set up. Professional testing costs $125–$400 and provides detailed hourly data.
Fix if needed
If levels are 4 pCi/L or higher, hire a certified professional to install a mitigation system. Most cost $800–$2,500 and are installed in a day.
Re-test regularly
Test every 2 years, after renovations, and annually if you have a mitigation system. Radon levels can change over time.
Test in real estate
Always test for radon when buying a home. If levels are high, negotiate mitigation into the purchase agreement.
The U.S. Surgeon General and the EPA recommend that all homes below the third floor be tested for radon. Given that testing is inexpensive and mitigation is effective, there is simply no good reason not to know your radon level. The knowledge alone can save your life.
Key Takeaways
- • Radon causes 21,000 lung cancer deaths per year — more than drunk driving and house fires combined
- • It's the #1 cause of lung cancer among non-smokers
- • Smokers exposed to radon face dramatically higher risk (synergistic effect)
- • Children, remote workers, and seniors face higher exposure due to time spent at home
- • There is no known safe level — any reduction decreases risk
- • Testing is cheap, mitigation works, and the problem is entirely solvable
Protect Your Family — Get a Free Radon Quote
Don't wait. Connect with certified radon professionals for testing or mitigation in your area.
Don't Gamble with Your Family's Health
Radon testing takes minutes to start and can save lives. Get free quotes from certified professionals.
✓ Free quotes ✓ Certified professionals ✓ No obligation