Get to know the second leading cause of lung cancer – Radon

Dr. Farhan M. Asrar receiving the 2017 CMA Young Leaders (Early Career) Award in August 2017.



YOU may have see ads about it, perhaps noticed flyers at your doctor’s office and you may have heard Mike Holmes and Mike Holmes Jr. speak about it. But do you really know Radon and the possible harms it can pose? Radon is an odourless and colourless gas which is radioactive and it is formed naturally from the breakdown of uranium in the soil.

Studies have shown there is a risk of lung cancer due to exposure to radon even at levels that are found in homes. In fact, radon is the second leading cause of lung cancer and 16% of lung cancers deaths in Canada are attributable to radon. This can be around 3,200 deaths each year.

Photo courtesy Health Canada

If you are a smoker then the risk is even worse. High level of Radon exposure alone can lead to lung cancer in 1 in 20 people but if someone smokes and is also exposed to high levels of Radon then the risk increases to around 30 % or 1 in 3 people!

Radon can enter homes through any opening which contacts the soil such as cracks or gaps in the foundation, floor drains, etc. All homes have some level of radon and current Canadian guideline for radon indoors is 200 Bq/m 3. However, around 7.9% of homes in British Columbia had radon levels above these guideline levels. Once radon enters, it can build up to levels that can pose a health concern.

The risk of lung cancer due to radon depends on three factors which include the level of radon that one is exposed to, the duration of the exposure, and if you smoke. So this is yet another reason why one should consider to quit smoking


What can you do about it?


Photo courtesy Health Canada

Firstly, get to know more about it, educate yourself and other about it. Health Canada offers a lot of helpful resources and information on Radon and what you can do if your levels are high. The only way you can know the level of radon in your home is to test for it. Radon test kits are widely available from hardware stores and online (they can range from around $30 to $60). Get the test kit and keep the detector in your home.

Health Canada recommends keeping it and testing it for a minimum of three months and preferable during winter. If radon levels found are above the guideline then H ealth Canada recommends taking steps to lower the level as soon as possible. They recommend hiring a Canadian National Radon Proficiency Program (C-NRPP) certified professional to work on approaches to reduce your levels. Radon reduction methods can reduce radon levels by 90%.

If you would like to know more about Radon, see Health Canada and its partner resources.

Additionally, Take Action on Radon and Canadian Association of Radon Scientists and Technologists have organized a National Radon Reduction Sweepstakes where you could have a chance to win a rebate of up to $1,000 towards radon reduction method costs. More details are available at


Dr. Farhan M. Asrar is Assistant Professor with the Department of Family and Community Medicine (DFCM), University of Toronto and cross-appointed with the Dalla Lana School of Public Health. He is also Physician Research Lead for the Credit Valley and Summerville Family Medicine Teaching Units, Mississauga (under Trillium Health Partners & University of Toronto). He is the 2017 recipient of the Canadian Medical Association’s Young Leaders Award (Early Career) which he received in August 2017.