A pitchfork rests in the earth, against the side of an old building, which could have radon leaking through the foundation. Share on Pinterest
Léa Jones/Stocksy United

Radon is a naturally occurring gas that forms from the breakdown of radioactive metals into groundwater, soil, or rock. Radon occurs naturally in the air in very small amounts. It’s measured using a unit of measure for radioactivity called a picocurie.

Radon can build to dangerous levels when it enters homes and other buildings through cracks in their foundations — and prolonged exposure to high amounts of radon has been linked to the development of lung cancer.

According to the Environment Protection Agency (EPA), radon exposure is the second most common cause of lung cancer and the top cause of lung cancer among nonsmokers.

Read on to learn more about the link between radon and lung cancer and how you can reduce your exposure.

Radon is a colorless and odorless radioactive gas. It forms from the breakdown of the radioactive metals radium, thorium, or uranium into soil, water, or rock.

Radon can escape from the ground and enter the atmosphere. It’s normal to be exposed to small amounts of radon every day in the air you breathe. According to the EPA, the natural average level of radon in outdoor air is 0.4 picocuries per liter (pCi/L).

But elevated levels have been reported in every state.

The national average for radon in indoor air is 1.3 pCi/L — much higher than the natural outdoor average. The EPA recommends taking action if radon levels in your home are above 4 pCi/L. They estimate that 1 in 15 homes have elevated radon levels.

Radon makes up about 40 percent of the radiation humans are exposed to.

Radon decays into tiny radioactive particles that release alpha rays. These particles mix with dust and aerosols in the atmosphere and enter your respiratory tract when you breathe in.

Once in your lungs, radioactive particles can ionize, or remove electrons, from the DNA of epithelial cells that line your lungs. After years of exposure, this ionization can cause changes in your DNA that lead to the uncontrollable replication of cells and tumor formation.

In a 2020 review of studies, researchers found that radon exposure increased the risk of all types of lung cancer. It has the strongest association with small-cell lung cancer. Small-cell lung cancer only makes up about 10 to 15 percent of lung cancers, but it tends to be aggressive and has fewer positive outcomes.

The researchers found that as radon exposure increased by 100 becquerels per meter cubed (Bq/m3), equivalent to 2.7 pCi/L:

Radon exposure is responsible for about 21,000 lung cancer deaths each year. About 2,900 occur in people who’ve never smoked.

Radon exposure doesn’t cause any immediate symptoms. Lung cancer usually develops after 5 to 25 years of exposure.

Early symptoms of lung cancer can include:

The more radon you’re exposed to and the longer you’re exposed, the more likely you are to develop lung cancer.

Smokers are at a higher risk of developing lung cancer caused by radon exposure than people who’ve never smoked due to the additional risk factors of nicotine and other chemicals in tobacco products.

The table below details the risk of developing lung cancer (based on EPA data).

Lifetime radon level exposurePredicted lung cancers per 1,000 smokersPredicted lung cancers per 1,000 people who never smoked
20 pCi/L260 people36 people
10 pCi/L150 people18 people
8 pCi/L120 people15 people
4 pCi/L62 people7 people
2 pCi/L32 people4 people
1.3 pCi/L20 people2 people
0.4 pCi/L3 people

It’s worth noting that it’s difficult to reduce your exposure to radon below 2 pCi/L.

For most people, their home is the largest potential source of radon exposure. People living in homes built above tailings from mines and mills are at an increased risk of radon exposure.

The following risk factors may also contribute to radon exposure:

  • Upper floors in buildings. Upper floors are often more affected than the lower floors when well water is the main source of radon.
  • Colder temperatures. In cold climates, radon levels are often highest in the winter and lowest in the summer.
  • Presence of static electricity. Radon can attach to dust particles more easily during times of year when static electricity is more prevalent.

Underground miners and people working in indoor enclosed spaces like factories, schools, warehouses, or offices may be exposed to elevated levels of radon.

If you notice any concerning symptoms, don’t hesitate to contact a primary healthcare professional. They’ll review your medical and family histories and perform a physical examination.

They may refer you for imaging tests like chest X-rays or CT scans to look for abnormalities in your lungs.

To confirm a lung cancer diagnosis, a small sample of lung cells needs to be taken for lab analysis.

Lung cancer treatment varies based on how far it’s spread and the specific type of lung cancer you have.

If lung cancer is caught in the early stages, surgery may be the only treatment option needed. Late stage lung cancer often requires chemotherapy and radiation therapy.

The two main subcategories of lung cancer are non-small cell and small-cell lung cancer. The CDC states that people with non-small lung cancer are usually treated with some combination of:

People with small-cell lung cancer are generally treated with radiation and chemotherapy.

You can reduce your exposure by:

  • Purchasing a home testing kit. Home testing kits can be purchased online or at home improvement stores for about $20 to $30 and only take minutes to use.
  • Improving airflow in your home. Use fans, vents, and open windows to improve fresh air circulation in your home.
  • Seal cracks in your floor and walls. Sealing cracks can help prevent radon from entering your home from the ground. You can find a list of qualified professionals from the EPA website.
  • Build radon-resistant techniques into your home. Try placing a heavy-duty polyethylene sheet on top of gravel at the foundation of your house to prevent gases from entering.
  • Contact the National Radon Program Services (NRPS). You can find more information on radon by contacting the NRPS.
    • Call 1–800–SOS–RADON (1–800–767–7236) for an automated system for recordings and ordering materials.
    • Call1–800–55–RADON (1–800–557–2366) to speak to an information specialist.

Radon is a radioactive gas that forms from the breakdown of radioactive metals in the ground.

Exposure to high amounts of this gas can increase your risk of developing lung cancer. One of the best ways to measure the levels of radon in your home is to buy a home radon testing kit.

Sealing up cracks in the walls and foundation of your house can help prevent radon from leaking into your home.