Lung Cancer Risks for Non-smokers

traffic jam on city streets with exhaust fumes coming from cars

As many as 20% of people who die from lung cancer in the United States every year have never smoked or used any other form of tobacco. This translates to about 30,000 Americans in 2018. In fact, if lung cancer in non-smokers had its own separate category, it would rank among the top 10 fatal cancers in the United States.

It’s still true that staying away from tobacco is the most important thing any of us can do to lower our risk of getting lung cancer. But there are also other risk factors. Researchers have made a lot of progress over the past decade in understanding what causes lung cancer in people who have never smoked:

  • Radon gas. The leading cause of lung cancer in non-smokers is exposure to radon gas, according to the US Environmental Protection Agency (EPA). It accounts for about 21,000 deaths from lung cancer each year.  About 2,900 of these deaths occur among people who never smoked. Radon occurs naturally outdoors in harmless amounts, but sometimes becomes concentrated in homes built on soil with natural uranium deposits. Studies have found that the risk of lung cancer is higher in those who have lived for many years in a radon-contaminated house. Because radon gas can’t be seen or smelled, the only way to know whether it’s a problem in your home is to test for it. A Citizen’s Guide to Radon explains how to test your home for radon easily and inexpensively, as well as what to do if your levels are too high.
  • Secondhand smoke. Each year, about 7,000 adults die of lung cancer as a result of breathing secondhand smoke. Laws that ban smoking in public places have helped to reduce this danger. The American Cancer Society Cancer Action NetworkSM (ACS CAN), the nonprofit, nonpartisan advocacy affiliate of the American Cancer Society, is working to expand and strengthen these laws to further protect both smokers and non-smokers from the dangers of secondhand smoke.
  • Cancer-causing agents at work. For some people, the workplace is a source of exposure to carcinogens like asbestos and diesel exhaust. Work-related exposure to such cancer-causing materials has decreased as the government and industry have taken steps to help protect workers. But if you work around these agents, you should be careful to limit your exposure whenever possible.
  • Air pollution. It’s long been known that both indoor and outdoor air pollution contribute to lung cancer. The World Health Organization (WHO) classifies outdoor air pollution as a cancer causing agent (carcinogen). However, the risk of lung cancer associated with air pollution is thought to be lower in the US than in many other countries because of policies that have helped to lower the levels of exposure.
  • Gene mutations. Researchers are learning more and more about what causes cells to become cancerous, and how lung cancer cells differ between people who have never smoked and smokers. Understanding how gene changes cause lung cancer cells to grow has helped researchers develop targeted therapies, drugs that specifically target these mutations.

Lifestyle changes to lower risk

Non-smokers have already eliminated their greatest risk factor for lung cancer. But non-smokers can make some lifestyle changes to help reduce their risk even more.

Testing your home for radon, avoiding secondhand smoke, and limiting exposures at work can help you avoid the leading causes of lung cancer in non-smokers.

healthy diet with lots of fruits and vegetables may also help reduce your risk of lung cancer. Some evidence suggests that a diet high in fruits and vegetables may help protect against lung cancer in both smokers and non-smokers. But any positive effect of fruits and vegetables on lung cancer risk would be much less than the increased risk from smoking.


The American Cancer Society medical and editorial content team

Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

American Cancer Society news stories are copyrighted material and are not intended to be used as press releases. For reprint requests, please see our Content Usage Policy.