Radon: Invisible health threat in the home By Jan MacAuley
UPdate Fall 2008

You take care of yourself. You eat nutritious foods, buy organic when available, exercise often and are careful not to expose your body to toxins. You appreciate the word ‘natural’ as synonymous with ‘good for you’. However, there is one naturally occurring substance that has the potential to damage your health in the place where you should feel the most protected from harm: your home.

Radon is a tasteless, odourless, colorless...and radioactive ...gas that results from the decay of uranium found naturally in certain types of bedrock, most commonly shale and granite. Radon gas is common in many parts of Nova Scotia. Although it forms deep underground, it travels through the soil to the earth’s surface, often exiting open ground and diffusing benignly into the atmosphere. However, It can also permeate the porous concrete foundations of homes and become concentrated in basements. As a gas, radon can also dissolve in groundwater and enter homes in rural areas via the well water supply.

Through the natural process of radioactive decay, radon transitions spontaneously through a series of elements known as radon decay products. As it does so, it emits three types of radiation: alpha, beta and gamma. It is the alpha particle that has the potential to do the most damage to human tissue.

Radon and its decay products are known human carcinogens. If they are present in the air we breathe, our lungs are constantly threatened with a dose of alpha radiation, as these substances may transition and release alpha particles at any moment. Such exposure can result in both physical and chemical damage to cellular DNA. Lung cancer is the potential consequence of repeated damage.

Radon exposure is the second leading cause of lung cancer in North America, preceded only by smoking and carrying a risk seven times higher than exposure to second hand smoke. Lung cancer, the deadliest of all cancers for both men and women, has a mortality rate of 84%, and it is estimated that 10-15% of those deaths can be attributed to radon. In Canada, radon induced lung cancer killed more Canadians in 2001 than homicides, accidental poisonings, and drowning-combined. How much you are at risk depends upon the concentration of radon present in your home, and the amount of time you spend there.

Indoor radon levels can fluctuate on a frequent, even daily, basis, depending on several factors. The strength of the source in the underlying bedrock is the most important determinate, but soil type, time of season, weather conditions as well as pressure changes created by the building itself also contribute significantly.

Granite and shale tend to contain higher levels of uranium than other types of rock, and so soils atop such rocks have more radon. How easily the radon can reach the surface depends upon the soil’s permeability. Moist clay soils are the most difficult to pass through, and dry sand is the easiest. Since gas condenses at lower temperatures, radon levels in soil are higher when it’s cold; a situation that is further compounded when there is a cap of snow on the ground. Because warm air within our homes causes an indoor low pressure system, this condensed radon can then be quite literally sucked into our basements, making it easy to see why indoor radon levels are often highest in winter.

Normally radon levels are highest closest to the source, so concentrations tend to be most pronounced in the lowest floor of a home. Thus, radon testing is always conducted on this level, in areas that are lived in the most, such as a bedroom or recreation room. However, poor air quality factors such as high humidity, dust and especially second hand cigarette smoke can compound the problem and help transport radon to higher floors, increasing potential exposure. Interestingly, some studies show that women are twice as likely as men to have radon induced lung cancer, a circumstance that could be the result of the increased domestic role they play in some family situations.

In February 2007, in response to domestic cancer studies as well as an international project initiated by the World Health Organization in 2005, Canada significantly lowered the level at which they recommend action be taken to reduce radon exposure in homes. Although no level of radon is considered ‘safe’, this new threshold is the first step toward recognizing and reducing the health risks posed to Canadians from residential radon exposure.

Nova Scotia is one of the areas of Canada where the potential of radon exposure is high in many parts of the province. High levels of radon have also been identified in the Northwest Territories and Manitoba. Although everyone should test for radon, homeowners in these provinces are especially encouraged to do so. Health Canada, in a joint initiative with Nova Scotia Environment and Labour, has begun certification programs for radon mitigation and measurement in this province. A directory of participating businesses recently certified to test in Nova Scotia can be found at:
www.gov.ns.ca/lwd/healthandsafety/consultants/ and www.healthfulhomes.ca.

If high levels of radon are found, measures can be taken to reduce these levels to reduce health risks

Not only is it important for homeowners, but home buyers should also test their prospective homes for radon, and home builders should consider incorporating features to protect against radon. While short-term radon testing in real estate transactions is a common practice in the United States, it is rarely done in Canada. Testing homes during a sale raises awareness and ensures that a radon problem is addressed before the new homeowners are exposed.

Jan MacAuley, a Real Estate Broker in the Halifax area, is committed to helping home buyers live in greener, healthier homes. Her company offers a unique service package that includes radon gas testing. www.healthfulhomes.ca

UPdate, Fall 2008, Environmental Health Association of Nova Scotia

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Radon: Invisible health threat in the home