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
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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Nine Facts You Need to Know about Uranium Mining
Radon: Invisible health threat in the home