Lung cancer is caused when cells in the lung mutate or change. Researchers have spent decades trying to understand what causes these cells to mutate. Most lung cancers are caused when someone repeatedly breathes in toxic substances. However, for some people, the cause of their lung cancer is never known.

Many causes of lung cancer have a synergistic effect. That means your risk of developing lung cancer greatly increases the more risk factors you have. For example, smoking and having high levels of radon in your home puts you at much greater risk for developing lung cancer than just one of those factors alone.

Below are the known environmental and health causes of lung cancer and what you can do to reduce your risk.

Cause: Smoking

The leading cause of lung cancer is smoking. There are approximately 600 ingredients in cigarettes. When burned, they create more than 7,000 chemicals. At least 69 of these chemicals are known to cause cancer, and many are poisonous, so it is no surprise that people who smoke have a higher risk of developing lung cancer. Secondhand smoke can also cause lung cancer so try and avoid it as much as you can.

Take action: Quit smoking and avoid secondhand smoke. Quitting smoking doesn’t completely remove your risk, but it greatly reduces it. Ask your doctor about lung cancer screening if you meet the high-risk criteria.

Read LUNG FORCE Hero Patricia’s experience with smoking, lung cancer and early detection.

Cause: Radon

Radon exposure is the second-leading cause of lung cancer. Radon is a colorless, odorless radioactive gas that exists naturally in soil and enters buildings through gaps and cracks. Radon can concentrate at dangerous levels in the home and can cause lung cancer. Every year 21,000 people die of lung cancer related to radon exposure.

Take action: Test your home for radon and remove it if the levels are high.

Read LUNG FORCE Hero Jan’s experience with radon and lung cancer.

Cause: Hazardous chemicals

Exposure to certain hazardous chemicals like asbestos, uranium, arsenic, cadmium, chromium, nickel and some petroleum products can cause lung cancer.  People also inhale these as toxic air pollutants from emissions from power plants or industry smokestacks, and sometimes from the workplaces.

Take action: If you are exposed to dust and fumes at work, ask your health and safety advisor how you are being protected. Always wear protective gear when working with hazardous chemicals. Help fight pollution. Work with others in your community to clean up the air you and your family breathe.

Read LUNG FORCE Hero Alan’s experience with hazardous chemicals and lung cancer.

Cause: Air pollution

Particle pollution, a mix of very tiny solid and liquid particles that are in the air we breathe, can cause lung cancer. Evidence shows that breathing particles—like those coming from diesel truck exhaust, power plants, and wood smoke—increases the risk of lung cancer.

Take action: Avoid exercising outdoors on bad air quality days. On really bad days, stay inside, especially during wildfire smoke. Help fight pollution. Work with others in your community to clean up the air you and your family breathe.

Read LUNG FORCE Hero Douglas’ story about how he fights for clean air.

Cause: Genetics

A family history of lung cancer may mean you are at a higher risk of getting the disease. To date, there is no “lung cancer gene” that has been discovered, but there are specific mutations that can be checked for that can be inherited, so knowing your family’s health history can help your doctor understand your full lung cancer risk.

Take action: If others in your family have or ever had lung cancer, it's important to share this with your doctor.

Read LUNG FORCE Hero Jaqueline’s experience with three family members diagnosed with lung cancer.

If you have questions about your risk of developing lung cancer, talk to your doctor or call the Lung HelpLine at 1-800-LUNGUSA (1800-568-4872).

For more information about lung cancer, visit

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