MRO Magazine

Is there hazardous radon in your workplace?


November 2, 2015
By Bill Roebuck

Burnaby, BC – You can’t see, smell or taste it, but radon is a radioactive gas that is released when uranium  — naturally present in rock and soil — decays. When the gas accumulates indoors, it can become hazardous to your health. November is Radon Action Month so it’s a good time to learn how you can test for radon and reduce your risk of exposure. (Editor’s note: This article was first published in the Canadian Centre for Occupational Health & Safety’s Health & Safety Report, Vol. 13, Issue 10, November 2015.)

Radon has been classified by the International Agency for Research on Cancer (IARC) as a known cause of cancer in humans. The risk of developing lung cancer from radon exposure depends on the level and length of exposure, and is increased if you are a smoker.

In Canada, radon is the leading cause of lung cancer for non-smokers. Health Canada estimates that about 16% of lung cancer deaths are related to radon exposure. According to the Canadian Cancer Society, this amounts to approximately 3,300 deaths each year. In smokers, radon exposure increases the risk of developing lung cancer from 1 in 20 to 1 in 3.

How and where radon exposure occurs


Radon seeps out of the ground into the surrounding air, water, and soil. In outdoor air, radon dissipates quickly. However, the gas becomes a hazard indoors where it can accumulate. The majority of radon enters buildings through ground or basement level rooms, wall slab joints, sump pits, crawl spaces, and cracks and openings in foundations. Indoor levels can increase over time because the gas enters a space faster than it can escape. Any home can have a radon problem, regardless of its age or building construction.

Radon concentrations vary across Canada and some regions experience higher indoor radon concentrations than others. However, all regions of the country have reported homes with elevated levels.

At work

The CAREX Canada team is currently developing an estimate of exposure to radon in Canadian workplaces. The jobs at highest risk of exposure to radon are those that work specifically with uranium, or those that occur underground or in the lower floor of buildings, such as miners, some subway workers, and utilities workers.

Specific occupational exposure limits have been set for federal employees covered by the Canada Labour Code and for uranium workers by the Canadian Nuclear Safety Commission. Other workplaces may be covered by the Naturally Occurring Radioactive Material (NORM) Guidelines, and the American Conference of Governmental Industrial Hygienists (ACGIH) has set occupational exposure limits for radon and radon daughters. Radon exposures should be kept under occupational exposure guidelines applicable to your jurisdiction.

Testing for radon

The only way to know if you’re being exposed to radon gas is to test for it. Because radon levels vary over time, Health Canada recommends using a long-term detector and testing for a minimum of three months, over the winter months if possible when homes tend to be sealed and ventilation is low.

If a worker has concerns about radon levels in a workplace, they can request a radon test.

Radon testing is available through certified service professionals who are listed on the Canadian Association of Radon Scientists and Technologists website and the Canadian National Radon Proficiency Program. You can also conduct the testing yourself by purchasing a do-it-yourself kit through your local Lung Association or hardware store, and following the Health Canada guidelines.

Reducing worker exposure to radon

In the workplace, employers should be aware of and recognize the potential for radon exposure. This may include radon exposure resulting from activities involving materials in which radon naturally occurs (i.e. mining uranium, burning coal or making fertilizer).

To reduce worker exposure, consider:

– Using raw materials that are low in naturally occurring radioactive materials.

– Designing and constructing, or modifying, buildings to prevent radon entry through soil gas — and facilitate its removal.

– Increasing air circulation by regularly opening windows or by installing mechanical ventilation.

– Implementing administrative controls such as reducing the time spent by workers in areas where excess radon may be present.

– Using NIOSH-approved respirators for radionuclides and radon daughters when engineering and administrative controls are insufficient.

The specific methods used to remove radon from existing buildings depend on several factors, including building construction and soil type. The most effective of these methods is called active sub-slab depressurization, where a remediator installs a pipe through the floor slab of the foundation. This pipe is attached to a fan that runs continuously to draw radon gas out from beneath the structure to the outdoors, where it is effectively diluted.

For new buildings, the National Building Code of Canada encourages builders to prevent radon entry by implementing what’s called a ‘roughed-in radon reduction system’ during construction. This procedure involves laying a polyethylene barrier under the slab, sealing the slab perimeter and all areas where pipes run through the slab, and installing airtight coverings for sump pit covers.

Other remediation approaches are summarized on Health Canada’s Radon Reduction Guide for Canadians page.

This article has been edited and shortened. It its original form, it was published in the Health & Safety Report and provided by CAREX Canada, a source of evidence on Canadians’ exposures to workplace and environmental carcinogens, to support the effort to raise awareness of radon exposure. For more information, visit or