Health Matters with Dra. Denise: Radon

Health Matters with Dra. Denise:  Radon

I just found out ate’s ninang, Tita Shirley—one of my mom’s closest friends–just died. Shocked, I asked inay what from. Lung cancer. The first thing that ran through my head is, “But she’s not a smoker! And no one in her family (I don’t think…) is!” And then I ran other possibilities in my head, and so today I want to write about radon.

November was Lung Cancer Awareness Month as well as Radon Action Month in Canada. Sadly, approximately 21,100 Canadians will die this year from lung cancer, and more than 3200 of those deaths are because of exposure to radon indoors. That’s 16% of lung cancer deaths attributable to radon (2009 Health Canada study). This represents >3200 deaths each year. In fact, radon is the second leading cause of lung cancer in Canada, after smoking.

Radon is a colourless, odourless, radioactive gas that is produced naturally by the breakdown of uranium in the ground. It can get anywhere it finds an opening where a building is in contact with the ground; any cracks, openings or gaps in foundation walls or floors provide route(s) of entry into a home or building.

Since the air pressure inside a house is normally lower than the pressure underneath or around the foundation, this pressure difference acts like a vacuum, drawing radon in through foundation cracks and other openings. Once inside the home, radon can build up to dangerous levels. All homes have some level of radon (unless they are on stilts or in a tree); the question is how much and the only way to know is to test. The Government of Canada Radon Guideline level is 200 Bq/m3. If the radon level in your home is high, it can be fixed!

The carcinogenicity of radon is supported by a consensus of opinion among national and international health organizations. Extensive epidemiological evidence from underground uranium miners and more recent residential radon studies in Europe and North America show that there is a measurable risk of developing lung cancer from radon exposure at levels commonly found in residential homes.

When inhaled, radon decay products can become deeply lodged in the lungs, where they emit ionizing radiation which can penetrate the cells of mucous membranes, bronchi, and other pulmonary tissues. The ionizing radiation energy affecting the bronchial epithelial cells is believed to initiate the process of carcinogenesis. Although radon-related lung cancers are mainly seen in the upper airways, radon increases the incidence of all histological types of lung cancer, including small cell carcinoma, adenocarcinoma, and squamous cell carcinoma.

Radon exposure represents almost 50% of a person’s lifetime radiation exposure. This risk for lung cancer exists for both smokers and non-smokers, although malignancy from radon exposure is especially likely to occur in cigarette smokers and those exposed to second-hand smoke. The combined effects of radon exposure and smoking create a RISK greater than the two actions separately. The lifetime risks listed in this table (above) represent the risk of developing lung cancer due to radon exposure and, for smokers, the combined risk of tobacco use and radon exposure.

Non-smokers exposed to radon at the new guideline of 200 Bq/m³ have a 2% chance of developing lung cancer. For a smoker, this risk increases to 17% at 200 Bq/m³. Compare this 2% risk for non-smokers to non-smokers exposed to ambient levels alone (1%). For a smoker, this risk increases to 12%. This exposure-related cancer rate is larger than many other types of cancer, including Hodgkin’s lymphoma, oral, stomach, brain cancer, and myeloma.

Testing for Radon

The ONLY way to know if you have a problem is to test your home for radon. There are two options:
1. Hire a certified radon measurement professional
2. Purchase a do-it-yourself test kit

To find a radon test kit or certified measurement professional go to:

Radon testing, like most environmental and Indoor Air Quality testing, is best done once homeowners have moved into a new home. Home Inspectors could provide radon information materials as a value-add for consideration once homeowners have moved into the home; or they could consider offering radon testing as an add-on service to the home inspection service as it does not fit into a half day inspection.

Homes should be tested using a long-term test device for a minimum of 3 months. This is because indoor radon levels vary greatly, even over a 24 hour period. Several factors including building design, building condition, occupancy pattern etc. influence radon levels in a house. Two houses built side-by-side can have different indoor radon levels. So, measurements gathered over a longer period of time will provide a better estimate of the annual average exposure.

At 800 Bq/m3 the risk for a non-smoker exposed to radon in indoor air is higher than for all common accidental deaths (car accident, drownings, falls fire etc..) combined. We take precautions against accidental deaths by putting on our seatbelts, wearing lifejackets or ensuring that our smoke detectors are working. Looking at the relative risks, it is clear that we should also be testing our homes for radon.

*The dose-response relationship between cigarette consumption, biochemical markers and risk of lung cancer

MR Law, JK Morris, HC Watt and NJ Wald 1997 and Canadian Individual Risk of radon-induced lung cancer for different exposure profiles Dr. Jing Chen 2005 Once tested, if the radon level is found to be high, reduce it! Reducing the amount of radon in your home is easy and can be done at a reasonable cost. Hire a certified radon mitigation professional to help you find the best way to reduce the radon level in your home. Techniques to lower radon levels are effective and can save lives. Radon levels in most homes can be reduced by more than 80% for about the same cost as other common home repairs such as replacing the furnace or air conditioner.

To find a certified mitigation professional go to:

It is important to understand that while the health risk from radon exposure below the Canadian Guideline is small, there is no level that is considered risk-free. It is the choice of each homeowner to decide what level of radon exposure they are willing to accept.

Kung may tinanim, may aanihin; health starts at home—please make sure it’s safe! Alagaan ninyo ang katawan at kalusugan ninyo! Take care, and mind your health!

About Dr. Denise Koh
Dr. Denise Koh is Manitoba’s Chief Occupational Medical Officer and Medical Officer of Health in Environmental Health and Emergency Preparedness. She is a Public Health specialist with additional training and experience in Family Medicine and Occupational Medicine. Follow her writing at: