Radon and Lung Cancer Risk: What the Numbers Mean for Huntsville Homes

Quick answer: Radon is the leading cause of lung cancer among people who have never smoked and the second leading cause overall; the EPA estimates about 21,000 U.S. lung cancer deaths a year. At 4 pCi/L, the EPA estimates about 7 in 1,000 never-smokers and 62 in 1,000 smokers would get lung cancer from a lifetime of exposure. The EPA says fix at 4 pCi/L or higher and consider fixing between 2 and 4.

Most people in Huntsville first hear about radon from a home inspector, a lender checklist or a neighbor who had a system put in. The next question is usually "how worried should I be?" This page lays out what the health agencies actually say, using the EPA's own risk chart and the World Health Organization's fact sheet, so you can put your test result in context. It is general information, not medical advice. We're a free referral service, not a contractor or a doctor; we connect you with independent, certified radon professionals.

How radon harms the lungs

Radon is a radioactive gas that comes from the natural breakdown of uranium in soil and rock. It has no color, smell or taste. Outdoors it disperses, but it can build up inside a house that sits on radon-producing ground. When you breathe it, radon and its short-lived decay products deliver radiation to the cells lining the airways, and over years that damage can lead to lung cancer. There are no early symptoms, which is why testing is the only way to know your level.

The big-picture numbers

The EPA estimates radon causes about 21,000 lung cancer deaths a year in the United States (with an uncertainty range of roughly 8,000 to 45,000), including about 2,900 among people who have never smoked.
Radon is the number one cause of lung cancer among non-smokers and the second leading cause overall, after smoking.
The WHO estimates radon causes 3% to 14% of all lung cancers, depending on a country's average radon level and smoking rate, and that lung cancer risk rises about 16% for every 100 Bq/m³ (about 2.7 pCi/L) of long-term exposure.
The U.S. Surgeon General issued a health advisory on radon in January 2005, urging Americans to test their homes.

What the EPA lifetime-risk chart says

The EPA publishes estimates of how many people out of 1,000 would get lung cancer if exposed to a given radon level over a lifetime. The difference between smokers and never-smokers is striking.

20 pCi/L: about 36 in 1,000 never-smokers; about 260 in 1,000 smokers.
10 pCi/L: about 18 never-smokers; about 150 smokers.
8 pCi/L: about 15 never-smokers; about 120 smokers.
4 pCi/L (EPA action level): about 7 never-smokers; about 62 smokers.
2 pCi/L: about 4 never-smokers; about 32 smokers.
1.3 pCi/L (average indoor level): about 2 never-smokers; about 20 smokers.
0.4 pCi/L (average outdoor level): fewer than 1 never-smoker; about 3 smokers.

Two things stand out. First, there is no level with zero risk; the chart simply gets smaller as the number drops. Second, smoking multiplies the danger. The WHO puts it this way: smokers are estimated to be about 25 times more at risk from radon than non-smokers. If anyone in the house smokes, lowering radon and quitting smoking both matter.

Why Huntsville and Madison County households should pay attention

Madison County is in EPA Radon Zone 1, the highest-potential category, and the Alabama Department of Public Health lists it among the 15 Alabama counties with the highest potential for elevated radon. The American Lung Association's 2022 report on CDC tracking data lists 5,178 Madison County tests with a mean of 4.0 pCi/L and about one in four results at or above 4 pCi/L. Those are homes that chose to test, many during sales, so they are not a random sample. But a county average sitting right at the action level is a good reason not to assume your house is fine.

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What to do with your result

No test yet: test the lowest lived-in level of the home. ADPH has offered free test kits to Alabama households while supplies last. See radon testing in Huntsville for kit and professional options.
Below 2 pCi/L: the EPA notes levels below 2 are difficult to reduce further. Retest every couple of years or after major renovations.
2 to 3.9 pCi/L: the EPA says to consider fixing. A long-term test (90 days or more) gives a better picture of your year-round average before you decide.
4 pCi/L or higher: the EPA recommends fixing the home. A properly installed active system, usually sub-slab depressurization on a slab or basement and a sealed membrane in a crawl space, typically cuts levels by 50% to 99%, according to the EPA's Consumer's Guide.

Cost is often what decides timing. Angi's 2026 data puts most radon mitigation jobs between about $805 and $1,326, with an average near $1,043; our Huntsville cost guide covers what moves the price. If you're in a home sale, see real estate radon testing for the timing questions.

Past exposure and your health

A high result can be unsettling, especially after years in the same house. The EPA's message is that lowering radon lowers your risk from that point forward, even if you've lived with high levels for a long time. If you have concerns about past exposure or lung health, talk with your doctor and mention your radon result and smoking history. The practical goal is to reduce what everyone in the house breathes from here on.

Frequently asked questions

Is 4 pCi/L a safe level of radon?

No level is risk-free. 4 pCi/L is the EPA's action level, where it recommends fixing the home. The EPA estimates about 7 in 1,000 never-smokers and 62 in 1,000 smokers exposed at 4 pCi/L over a lifetime would get lung cancer, and it suggests considering a fix between 2 and 4 pCi/L.

Does radon cause symptoms like headaches or coughing?

Radon causes no immediate symptoms, so you can't tell your level by how you feel. The established health effect is lung cancer after long-term exposure, which is why the EPA and the Surgeon General recommend testing every home.

Why is radon more dangerous for smokers?

Smoking and radon damage the lungs together. In the EPA chart, the lifetime risk for smokers at a given level is many times higher than for never-smokers, and the WHO estimates smokers are about 25 times more at risk from radon than non-smokers.

How much does a mitigation system lower radon?

The EPA's Consumer's Guide says sub-slab and drain-tile suction systems typically reduce radon by 50% to 99%. Always retest after installation to confirm the result.

Is radon a real issue in Madison County?

Yes. Madison County is EPA Zone 1, ADPH lists it among Alabama's highest-potential counties, and the ALA's 2022 summary of CDC data shows a mean of 4.0 pCi/L across 5,178 tests, with about a quarter at or above 4.