A common environmental cause of lung cancer (and it’s not cigarettes)

Am I the only one who’s surprised when a non-smoker is diagnosed with lung cancer? The campaign against cigarette smoking in the US has largely been successful and has prevented thousands of cancer deaths. But cigarette smoke is not the only carcinogen in our environments that can cause cancer of the lung. Exposure to radon may be associated with up to 25,000 respiratory cancer deaths in the US per year, making it the second leading cause of lung cancer. In non-smokers, it is the leading cause.

What is radon?

Radon is produced naturally within the earth’s crust during the breakdown of radioactive elements. It is a colorless, odorless, radioactive gas that makes its way upward towards the earth’s surface and can collect in the low-lying areas of buildings with foundation cracks or poor ventilation. Radon is then inhaled with normal air, and the radioactive alpha particles collect in the lungs where they rapidly decay while delivering a dose of radiation. There are no immediate symptoms from exposure to radon, and the level and duration of exposure required to cause cancer are unknown. Some studies have reported an increase in the risk of leukemia in children living in areas with high levels of radon. With on-going exposure, such as spending time in the basement of an affected home, the risk of lung cancer – which would appear many years later – rises.

Radon is found all over the United States and can appear in pockets even in areas where levels are generally low. Many homes may be affected, depending on local geography and building materials used in construction. In 2005 more residences had radon levels above the EPA reference level than at any other time in history, nearly one home in 15. Click here for a map of radon zones in the US. It is important to remember that radon has been detected in homes in all three zones, so this map should not be used to decide whether your home or school should be tested.

The US Environmental Protection Agency has recommended a level of less then 4 pCi/L (picoCuries of radon per liter of air) in homes, and that all living spaces below the third floor be tested for radon regardless of geographic location. Below is a table taken from the EPA website that shows the relative risk of cancer from exposure to various levels of radon.

Radon Risk If You’ve Never Smoked

Radon Level

If 1,000 people who never smoked were exposed to this level over a lifetime*…

The risk of cancer from radon exposure compares to**…


20 pCi/L

About 36 people could get lung cancer

35 times the risk of drowning

Fix your home

10 pCi/L

About 18 people could get lung cancer

20 times the risk of dying in a home fire

Fix your home

8 pCi/L

About 15 people could get lung cancer

4 times the risk of dying in a fall

Fix your home

4 pCi/L

About 7 people could get lung cancer

The risk of dying in a car crash

Fix your home

2 pCi/L

About 4 persons could get lung cancer

The risk of dying from poison

Consider fixing between 2 and 4 pCi/L

1.3 pCi/L

About 2 people could get lung cancer

(Average indoor radon level)

(Reducing radon levels below
2 pCi/L is difficult.)

0.4 pCi/L

(Average outdoor radon level)

Note: If you are a former smoker, your risk may be higher.
* Lifetime risk of lung cancer deaths from EPA Assessment of Risks from Radon in Homes (EPA 402-R-03-003).
** Comparison data calculated using the Centers for Disease Control and Prevention’s 1999-2001 National Center for Injury Prevention and Control Reports.

 What can you do?

Even though radon reduction programs for schools and homes have not received sufficient attention in recent years, parents and homeowners should be aware of the EPA’s recommendation to have all schools and homes tested, regardless of geographic location. Radon detectors may be purchased from most hardware stores and should be used in all areas below the third floor. The National Radon Program Service at Kansas State University offers discounted test kits available for purchase online at http://sosradon.org/test-kits. If elevated levels are found in your home, mitigation should be carried out. This is not a complex process and usually involves simply venting air from below the house to the outside.

Where can I get more information?

 A Citizen’s Guide to Radon on the EPA website at http://www.epa.gov/radon/pubs/citguide.html


Angell WJ. 2008. The US radon problem, policy, program and industry: achievements, challenges and strategies. Radiat Prot Dosimetry;130(1):8-13.[abstract]

Mason:Murray and Nadel’s Textbook of Respiratory Medicine, 5th ed. Chapter 46, Epidemiology of Lung Cancer. W.B. Saunders 2010.

Acknowledgements to Dr. Dan Bakston, Occupational and Environmental Medicine resident at the University of Illinois at Chicago, for his work on this post.


3 thoughts on “A common environmental cause of lung cancer (and it’s not cigarettes)

  1. Thank you for this informative post Dr. Buchanan. The chart you included was particularly helpful. I’m going to test my house in the very near future!

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