Radon and Lung Cancer

Have You Tested for This Hidden Cause of Lung Cancer?

Radon is a radioactive gas that arises naturally from the uranium found in rocks and soils all over the world. You can't see or smell it, but it is the second leading cause of lung cancer after smoking and the number one cause of lung cancer in non-smokers.

Researchers established the link between radon and lung cancer during the 1950s and 1960s, but in recent years, there has been an increase in the number of never-smokers with lung cancer linked to radon. Despite the risk, too few people have tested their homes for exposure.

This article discusses the link between radon and lung cancer, and what you can do to test your own home or workplace for the gas. It also offers resources for those who need more radon information.

Verywell / Mira Norian

What Radon Is

Radon is an odorless, colorless gas that is released from the normal decay of uranium in the soil. Radon can enter homes through cracks in the foundation, floors, and walls, through openings around sump pumps and drains, and through gaps around pipes.

Radon may also be present in the water supply. It affects both old and new homes. It also doesn't matter what your neighbor's radon level is, though if they have an elevated level, your risk is likely higher. This is because radon levels vary greatly even in the same geographical area.

Radon is responsible for roughly 21,000 cancer deaths per year in the United States, with children and people assigned female at birth likely at greater risk.

How Radon Causes Cancer

Radon gas causes cancer because it is a radioactive gas. It breaks down into other radioactive substances, such as lead-214 or polonium-218, which are called its progeny. Together, they account for about 55% of the natural exposure to radiation that humans ever experience.

These exposures can damage human lung cells when breathed in over time. This is known to lead to the cell changes that cause lung cancer, although radon may also be linked to stomach, kidney, and other types of cancers. Studies of uranium miners around the world have shown a higher incidence of leukemia as well.


All homes should be tested for radon, though some U.S. regions are more likely to have elevated levels. The Environmental Protection Agency (EPA) has a radon zone map of risks for each state so that you can see if the overall risk is higher where you live. Some states also have their own radon risk resources.

There are several different ways to test for radon, with varying levels of price and accuracy. They range from basic and inexpensive charcoal tests, which can be set up for a period of days and then sent to a lab for results, to advanced digital models that continuously monitor radon.

These digital models can be pricey but work much like your smoke or carbon monoxide detector does.

Do-it-yourself kits are available at most hardware stores and can also be ordered online. If you are purchasing a home, your home inspection agency may offer radon testing as part of the service. If you are building a new home, check into radon-resistant construction. 

One growing area of radon research looks at building codes and construction materials to better understand the public health risks of radon exposure. That's especially the case as energy efficiency and building standards become more strict for sustainability reasons.

What Do the Results Mean?

Radon standards can vary by nation. In the U.S., a radon level over 4pCi/L (pico curies per liter) is considered abnormally high and should be repaired. Repair should also be considered for levels between 2pCi/L and 4pCi/L. In Canada, any level over 2pCi/L is too high.

To understand the significance of these levels, the EPA has done a risk assessment for radon in homes. A radon level of 4pCi/L is considered five times more likely to result in lung cancer diagnosis when compared with the risk of dying in a car crash.

However, raising awareness about the lung cancer risk and radon testing remains a challenge. North Dakota has some of the highest radon levels in the U.S., but even healthcare providers fail to test. A survey of 350 North Dakota physicians found 70% of respondents knew of radon's radioactivity but:

  • Sixty-seven percent of the responding physicians did not inform patients about radon.
  • Eighty percent never discuss the raised risk of radon exposure for smokers.
  • Only 35% of the respondents test their own homes for radon.

Radon Mitigation

If radon results are elevated, repairs usually cost between $800 and $2500. Certified contractors can be found through the EPA’s state radon contact site.

Other resources available to help you solve a residential radon problem include:

  • National Radon Hotline: 1-800-767-7236
  • National Radon Helpline: 1-800-557-2366
  • National Radon Fix-It Line: 1-800-644-6999


Radon is the leading cause of lung cancer among people who have never smoked, and the overall top cause of lung cancer behind smoking. The odorless, invisible gas found in U.S. buildings also raises the risk of lung cancer in people who do smoke.

Radioactive radon gas and its related elements, such as lead, seep into buildings from the surrounding soil. Radon also can be detected in water supplies.

To fix the problem, you'll first need to test for radon. If the results are higher than 4pCi/L, then radon mitigation is in order. You may wish to consider mitigation if the results are between 2pCi/L and 4pCi/L.

A Word From Verywell

It's important to know about your radon risk at home as well as at school and at work. Don't hesitate to ask for radon exposure data from your employer, school district, or other organization where you think you may be exposed.

Frequently Asked Questions

  • Does Radon Cause Other Health Conditions Beyond Cancer?

    It may, but so far the research is inconclusive. One study of 189 people diagnosed with chronic obstructive pulmonary disease (COPD) in Spain found no relationship between their illness and radon exposure. On the other hand, a South Korean study of 28,557 cases did find a higher incidence of stroke in older people exposed to indoor radon.

  • Is Radon More of a Lung Cancer Risk for People Assigned Female at Birth?

    It's true that lung cancer is on the rise in people assigned female at birth, and among never-smokers. That doesn't necessarily mean radon is always the cause. Factors such as genetic and hormonal changes, or exposure to other toxins like secondhand smoke and indoor pollution from cooking, also may be at work.

13 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Centers for Disease Control and Prevention. What are the risk factors for lung cancer?

  2. Environmental Protection Agency. What Is Radon Gas?

  3. Jobbágy V, Altzitzoglou T, Malo P, Tanner V, Hult M. A brief overview on radon measurements in drinking waterJournal of Environmental Radioactivity. 2017;173:18-24. doi: 10.1016/j.jenvrad.2016.09.019

  4. Vogeltanz-Holm N, Schwartz GG. Radon and lung cancer: What does the public really know? Journal of Environmental Radioactivity. 2018;192:26-31. doi: 10.1016/j.jenvrad.2018.05.017

  5. Degu Belete G, Alemu Anteneh Y. General overview of radon studies in health hazard perspectives. Journal of Oncology. 2021;2021:1-7. doi: 10.1155/2021/6659795

  6. Kelly‐Reif K, Sandler DP, Shore D, et al. Radon and cancer mortality among underground uranium miners in the Příbram region of the Czech RepublicAm J Ind Med. 2020;63(10):859-867. doi: 10.1002%2Fajim.23167

  7. Environmental Protection Agency. EPA Map of Radon Zones.

  8. Khan SM, Pearson DD, Rönnqvist T, Nielsen ME, Taron JM, Goodarzi AA. Rising Canadian and falling Swedish radon gas exposure as a consequence of 20th to 21st century residential build practicesSci Rep. 2021;11(1):17551. doi: 10.1038/s41598-021-96928-x

  9. Environmental Protection Agency. Health Risk of Radon.

  10. Schmitz D, Klug MG, Schwartz GG. Radon knowledge and practices among family physicians in a high radon stateJ Am Board Fam Med. 2021;34(3):602-607. doi: 10.3122/jabfm.2021.03.200553

  11. Pando-Sandoval A, Ruano-Ravina A, Torres-Durán M, Dacal-Quintas R, Valdés-Cuadrado L, Hernández-Hernández JR, et al. Residential radon and characteristics of chronic obstructive pulmonary diseaseSci Rep. 2022;12(1):1381. doi: 10.1038/s41598-022-05421-6

  12. Kim SH, Park JM, Kim H. The prevalence of stroke according to indoor radon concentration in South Koreans: Nationwide cross section studyMedicine. 2020;99(4):e18859. doi: 10.1097/md.0000000000018859

  13. Ragavan M, Patel MI. The evolving landscape of sex-based differences in lung cancer: a distinct disease in womenEur Respir Rev. 2022;31(163):210100. doi: 10.1183/16000617.0100-2021

Additional Reading

By Lynne Eldridge, MD
 Lynne Eldrige, MD, is a lung cancer physician, patient advocate, and award-winning author of "Avoiding Cancer One Day at a Time."