Radon is a naturally occurring ra­dioactive gas produced from the fission of uranium in bed­rock. Radon decays to alpha-emitting metals that, once inhaled, can damage DNA in the lung’s epithelial surfaces. Radon is the leading cause of lung cancer in nonsmokers and increases the risk of lung cancer in smokers. Exposure to radon accounts for more than 3000 lung cancer deaths annually across Canada, with more than 200 deaths in BC alone.[1] 

Although radon is present in outdoor air, typically at low concentrations, exposure becomes a concern when it accumulates in indoor spaces. Because radon is a gas, it can infiltrate indoors, moving from rock and soil through permeable building foundations. 

Indoor radon concentrations depend on sub-soil types, foundation treatments, housing characteristics, and ventilation/heating conditions; con­centrations can vary dramatically between homes located in the same neighborhood. The highest radon concentrations tend to occur in the lowest level of a building, such as basements. 

In 2007 Health Canada lowered the guideline for annual radon concentrations from 800 to 200 Bq/m3, bringing it closer to those of the US Environmental Protection Agency (150 Bq/m3) and the World Health Or­ganization (100 Bq/m3).[2] 

Although many homes in BC may have radon concentrations below the Health Ca­nada guideline, particularly those lo­cated in the Lower Mainland and on Vancouver Island, “hotspots” can be found throughout the interior and northern parts of the province (Figure [11]). For example, Dana Schmidt, of the Donna Schmidt Memorial Lung Cancer Prevention Society, reports that over 44% of homes tested in Castlegar are above the 200 Bq/m3 guideline.[3] 

Health Canada recommends that everyone test for radon, preferably over a minimum 3-month period during winter (when concentrations are highest) with the radon monitor placed at the lowest lived-in level of the home. Testing is easy and inexpensive: both the Northern Health Authority[4] and BC Lung Association[5] provide kits at reduced cost ($30) while the Donna Schmidt Society offers kits for free.[3] 

Although multiple organizations have spread the radon message, many Bri­tish Columbians may remain unknowingly exposed to elevated radon concentrations in their homes. Physicians can champion this important public health issue by talking to their patients about the dangers of radon and by encouraging them to test their homes. Homes with children, because their lungs may be damaged earlier, and homes with smokers, because of the synergistic effects of cigarette smoke and radon, should especially be tested. 

Home testing is only part of the solution. If high levels are found, homes must be mitigated. Mitigation involves either limiting entry of radon into the home or expelling radon to the outdoors before it reaches lived-in spaces. The first approach uses passive measures, such as sealing cracks or laying a gravel base and a polyethylene barrier under the foundation. The second, more effective approach uses active measures, such as sub-slab depressurization which employs a fan to push radon-containing air outdoors from under the home. 

Barriers exist for individuals wanting to mitigate and these are not unique to BC. Mitigation of existing homes can cost owners anywhere from a few hundred to a few thousand dollars,[6] and there is currently a lack of certified mitigators to do the work. 

The im­plementation of premitigation building code measures can ensure that new homes are ready for active mitigation and, to a small degree, can help lower radon entry through passive measures. However, since no testing is required before occupancy, individuals may falsely assume that residential radon is not an important issue in areas where such building code measures exist. Testing should be conducted in all new homes, and if concentrations are above the Health Canada guideline, active mitigation should be instituted.

Reducing residential radon levels, and ultimately the number of radon-related lung cancer deaths, should be a public health priority. Physicians can play an important role in achieving this goal by raising awareness among their patients, particularly for children and smokers, and by encouraging them to test and reduce radon levels in their homes.
—Prabjit Barn, MSc
Environmental Health Scientist, Environmental Health Services
—Tom Kosatsky, MD
Medical Director, Environmental Health Services
BC Centre for Disease Control

References

1.    Chen J. Radon and lung cancer. [Presentation]. Vancouver 2012. Accessed 10 April 2012. www.bc.lung.ca/association_and_services/documents/1-JChen_000.pdf.  [12]
2.    Health Canada. Government of Canada radon guideline. Ottawa 2009. Accessed 14 March 2012. www.hc-sc.gc.ca/ewh-semt/radiation/radon/guidelines_lignes_directrice-en... [13].
3.    Schmidt D. Radon in the West Kootenays. [Presentation]. Vancouver 2012. Ac­cessed 10 April 2012. www.bc.lung.ca/association_and_services/documents/10-DSchmidt_001.pdf.  [14]
4.    Northern Health Authority. Radon. 2011. Accessed 14 March 2012. www.northernhealth.ca/YourHealth/EnvironmentalHealth/Radon.aspx [15].
5.    British Columbia Lung Association. Initiatives - radon. Vancouver, BC: BC Lung Association; 2011. Accessed 14 March 2012. www.bc.lung.ca/airquality/airquality_radon_qanda.html [16].
6.    National Collaborating Centre for Environmental Health. Effective interventions to reduce indoor radon levels Vancouver2008. Accessed 14 March 2012. www.ncceh.ca/sites/default/files/Radon_Interventions_Dec_2008.pdf [17].