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It's everywhere. We are exposed with each breath we take; it causes lung cancer and, each year for over 150 of us in Atlantic Canada, it will cause our demise.  Yet, few of us are aware of this naturally occurring killer.

The few who are, know it as radon gas.

A colourless, odourless, and tasteless radioactive gas, radon results from the breakdown of uranium in soil, rock and water. It further breaks down into, what are commonly called, radon "daughters" that emit high-energy alpha radiation and cause the most damage once inside our lungs. Normally not a hazard outdoors, because of natural dispersion by the atmosphere, radon becomes a significant hazard when trapped in enclosed spaces like our homes. It enters buildings from the ground through openings such as cracks in foundation walls, utility penetrations, sumps, floor drains and sometimes from the building materials themselves. Potable water, if supplied from groundwater sources, can also be a source of radon. It's released from the water when we shower or turn on our taps and can add up to 2 per cent to the indoor concentration.

Experts now consider radon to be the leading cause of lung cancer after tobacco smoke. In fact, the World Health Organization estimates that, globally, radon gas causes between 6 and 15 per cent of all lung cancers. That means radon gas caused between 110 and 276 of the 1,840 lung cancer deaths in Atlantic Canada in 2008. While smoking is considered the major cause of lung cancer, smokers face at least six times greater risk from radon exposure because of a synergistic, or combined, effect between tobacco smoke and radon. Once trapped inside the lung radon daughters attach themselves to dust and smoke particles and irradiate lung tissue cells. The resulting effect is believed to initiate the cancer process.

Canada, like most developed countries, has for many years, had a radon guideline for homes. Until recently, that guideline was based on scientific information gained from studying the effects of radon on uranium miners. In 2005 the outcomes of two major new radon studies showed a direct link between exposure to residential radon gas and lung cancer. As a consequence, in 2007, with co-operation from all Provinces and Territories, Health Canada lowered the indoor air radon guideline, for yearly exposure, from 800 Becquerels (800Bq/m3) per cubic metre of air, to 200 Becquerels (200Bq/m3) per cubic metre of air. A Becquerel (named for the Nobel prize-winning French Physicist, Henri Becquerel) is a measure of radioactivity and represents one atom disintegrating per second. According to Health Canada, this guideline change will save 350 Canadian lives annually, 25 of them here in this region. The change also extends the guideline's application to, "dwellings", a name used by Health Canada to define buildings that have high occupancy rates by the public. Included, in addition to residential homes, are schools, hospitals, long term care residences and correctional facilities.

Since the introduction of the new radon guideline, governments in Atlantic Canada, except Newfoundland and Labrador, are testing public buildings in known radon prone areas. These areas are selected based on geology and, where available, the results of previous testing. Test results from 2008 show all jurisdictions with buildings above the National guideline-some significantly. Last winter, in phase one of a long-term plan, New Brunswick tested 27 schools and found 44 per cent exceeded the restriction. A number of these schools are being re-tested. The Province also tested homes in the Harvey area; however, the results are not yet available. On Prince Edward Island eight percent of 87 buildings were over the limit. June 2008 results for Nova Scotia show 331buildings were tested, the most in the region, with 38 percent of them above the guideline.  Newfoundland and Labrador is still at the planning stage: (and their results will be interesting as the Province is known to have deposits of uranium, especially in Labrador).

Following the confirmation of test results, each jurisdiction moves to the next stage-remediation, based on a national protocol set by Health Canada. It recommends buildings with results higher than 600 Bq/m3 be made safe within one year and those with levels 200 to 600Bq/m3 within two years.

Despite the efforts of governments to address the radon issue in public buildings, few of us are testing where we receive the most exposure-in our homes. Yet, it's a simple process. All we need is a radon detector; a variety of which are available for less than $100 including the cost of analysis. Easy to follow instructions, that come with the units, provide direction as to their placement. Because radon levels vary based on factors like atmospheric conditions, geology, ventilation, lifestyle and others long-term tests provide the best results. Health Canada recommends testing for 91 days, or more, in the heating season; a period when radon levels can increase. Since radon is heavier than air, the detector should be placed in the lowest lived-in area of a dwelling; in a room that is occupied four or more hours a day. Bedrooms are usually a good choice. Once the test is complete, the detector is returned to the supplier and a report is received within three weeks. Health Canada's remediation protocol should then be followed if the result exceeded the guideline. A deviation from this procedure is common in real estate transactions where shorter-term tests, usually 48 hours, are common. These should be followed up with longer tests as soon as possible.

Exposure to radon, like exposure to other health risks, can be reduced in several ways, starting with the testing of our homes and fixing them if radon levels exceed the guideline. Remedial action can be relatively cheap and simple when levels are low; or quite extensive and expensive in extreme cases.

Other Initiatives like geology-based radon mapping, to geographically outline potential radon areas, are useful and are underway in some jurisdictions. Nova Scotia leads the way in Atlantic Canada with a draft map already developed. Protocols, already in building codes, to prevent radon entry into buildings should be followed, and monitored, during the construction phase. Passive removal systems installed in buildings during construction and made active, if necessary, following completion are most effective in lowering radon exposure.

Making radon testing mandatory in real estate transactions would help tremendously. And, if there is the political will, the greatest challenge of all-public indifference-should be overcome through the establishment of public awareness campaigns. 

(Additional information on radon can be obtained in: Radon, A Guide for Canadian Homeowners available by calling: 1-800-668-2642 and online at: or:

Note: P. J. Wall has more than 40 years experience as a Radiation Specialist, a radon consultant and the former chairman of Nova Scotia's Radon Advisory Committe .  He is a co-author of the Canadian Guidelines for the Management of Naturally Occurring Radioactive Materials, a member of the Canadian Radiation Protection Association and former editor of its publication: "The Bulletin".

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