Radon Awareness


I was explaining to my neighbour that November is Radon Awareness Month. "We should do our part in aiding this good cause and maybe help to save some lives."

"What is Radon?" he asked.

That's the question I most often get when people first hear the word "Radon".

When you have finished reading this article you will understand what Radon is, where it is, when and why you need to take action, and who can give you professional guidance when it comes to the Radon risk that may exist in your home.

The Canadian National Radon Proficiency Program (C-NRPP) defines Radon as follows: "Radon is a tasteless, odourless and invisible radioactive gas that results from decaying uranium and is a leading cause of lung cancer."

So, Radon is dangerous and the leading cause of lung cancer in Canada, after tobacco use.Health Canada estimates that Radon kills 3,200 Canadians every year. And it is everywhere. It is a radioactive soil gas created when naturally occurring radioactive ground and soil materials deteriorate. Radon continuously seeps from the earth, usually harmlessly into the atmosphere.In lower ambient concentrations, as it occurs outdoors, it is harmless to animals and humans. However, in higher concentrations it can damage the DNA in cells in the lungs, giving rise to lung cancer. You should take it very seriously as it kills thousands of people around the world annually.

Modern homes, like those built in the last 200 years, are enclosures that may readily trap soil gases in the basement, in particular, and in the home in general. The newer the home, the more tightly it is sealed to reduce energy costs related to heating and cooling. All these homes may accumulate higher levels of Radon concentration, to the point where, over time, it becomes dangerous for the homes' occupants.

Where & When It Occurs

Different homes in the same neighbourhood may have very different Radon levels. The variables that determine this include the efficacy of ventilation systems, the surrounding soil types, the foundation backfill mineral contents, and the presence of foundation and basement floor cracks and openings. For example, foundations that are surrounded by clay-based soils may (but not necessarily) have less Radon accumulation because soil gases pass more readily through rocky, sandy soil types than they do clay.Granite and some other rocks and related soil types typically have a higher level of radioactivity. A home may be built in an area with lower ambient Radon levels, but the foundation may have been backfilled with materials that have greater radioactivity. This is why all homes should be tested, regardless of proven Radon levels in other nearby homes. Again, Radon is everywhere.


There are a variety of approved devices for measuring Radon levels in the home. Professional Radon technologists should only be using those devices that have been approved by the C-NRPP. You can find a list of those devices here. Professionals trained to the C-NRPP standards must take a rigorous course and pass an exam to gain full membership to the Canadian Association of Radon Scientists & Technicians (CARST). They also must meet annual education requirements on an ongoing basis to maintain their standing. When booking a Radon measurement, be sure to confirm that the technician is a member of CARST.

There are very specific protocols to be used to ensure that accurate measurements are obtained.Long term measurements must have a minimum duration of 91 days. Ideally, the long-term measurement takes place during the heating season, when Radon concentrations are typically at their highest. Long -term measurement kits are widely available in hardware stores at a very reasonable cost: C_NRPP approved/certified test kit providers can be found on the Take Action on Radon website Test and Reduce Radon in Your Home - Take Action on Radon. The kit comes with explicit instructions for placement of the device and packaging for sending the kit to a lab for analysis after the requisite amount of time has passed.

The present standard for a valid short-term measurement includes a minimum test period of 4 days (96 hours) and requires very specialized equipment. Ideally the home remains in a closed state for the duration of a short-term measurement.Regular household activities and HVAC system use are permissible during this protocol, but windows should remain closed and exhaust fan use should be minimal. This is done to ensure a more consistent air pressure inside the home. A negative air pressure in the home may cause more radon to be pulled into the home through cracks and openings in the foundation walls and basement floor. Keeping the windows closed aids in maintaining a more consistent air pressure during the measurement. There are other important details that also apply to the testing environment; a CARST certified technician will explain those in detail at the time the measurement device is placed in the home (most often in the basement).

Short-term measurements, along with a professional home inspection, are done frequently as part of the due diligence period when a home is changing hands – to inform the buyer if the home has safe levels of Radon.A high Radon measurement during a short-term test should be followed up with a long-term test to determine if and what kind of mitigation measures are needed.If you live in a home that has never been tested, you should opt for the long-term measurement.

What Is a Safe Level?

Radon levels in Canada use a unit of measure known as a Becquerel per cubic meter of air, expressed as Bq/m3. The average outdoor level of Radon is 5-15 Bq/m3. The actionable level of Radon in a home in Canada is 200 Bq/m3 or greater. If a short-term measurement produces that result, the odds are highly in favour of a similar result when the more reliable long-term measurement is completed. If the Radon concentration is below 200 Bq/m3, no action is required, but depending how close it is to that level, you may want to follow up with an annual test.With detected levels of 200-600 Bq/m3, it is recommended that remedial action be undertaken within 2 years. Levels above 600 Bq/m3 require remedial action within 1 year.After a proper long-term measurement has been completed, you can purchase a relatively inexpensive Radon monitor to provide an active measurement on an ongoing basis. Some devices are better than others. Be certain to do some research before making such a purchase.


There are a variety of possible mitigation methods. These are best determined by a CARST certified mitigation technician and will be designed according to the level of detected radon and the building's conditions. Most of these active mitigation efforts will include the installation of a fan device that depressurizes the underside of the basement floor slab by exhausting air under the slab directly to the outdoors. After a mitigation system is installed, a follow-up measurement should be made to confirm the system's efficacy.

New Homes

Given the potential health risks associated with high Radon concentrations in homes, newly constructed homes in some provinces must have now a rough-in soil pipe installed to accommodate a mitigation system should it be determined that one is required.The floor slabs in new homes are now built over an underlying membrane that is impermeable to air movement, so if cracks do occur in the concrete floor slab Radon is less likely to seep into the home.Heat Recovery Ventilators (HRV) are now installed in all new homes.This replaces stale and humid indoor air with fresh exterior air multiple times per day, thus reducing the likelihood of higher concentration of soil gases in the home.Regardless of the age of the home, at least one long term test should be conducted as soon as you take possession of any home.

Who Can Help

Health Canada, together with other interested parties, have established the potential Radon risks and guidelines for mitigating those risks. The Canadian Lung Association is extensively involved in the Radon discussion and even offers mitigation grants for lower income Canadians. CARST publishes a list, sorted geographically, of qualified technicians on their website.

Many members of the Canadian Association of Home & Property Inspectors have completed the requirements to become a CARST member and can provide short and long-term measurement services.If mitigation is required, CARST also publishes a list of technicians that are qualified to design and install appropriate measures.

The take-away, now that you have read this article, is that all homes need to have a Radon measurement completed. Please tell all your friends and family members to do the same, to keep them safe from the potentially serious harm to their lungs and lives.

The Heat Is On
Your Foundation – From the Ground Up
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