September 12, 2017
By now I'm sure many of you reading this have heard customers, clients, or even friends and neighbours mention the dreaded R-word… I'm also sure many of you have not. It's remarkable how an issue so well-known and addressed in both the public sphere and in the building and housing industries in the US and Europe has taken so long to gain widespread attention here in Canada. Regardless, it's here now and it's only getting bigger. Radon is an important issue for homeowners and builders alike, and it presents some great potential opportunities for the HVAC contractor-in-the-know.
First, let's look at what exactly we're dealing with (without getting too technical). Radon is a naturally occurring soil gas; invisible and odourless. It is present in rocks, soils and water and is released into the air - sometimes outside, where it's concentration is negligible - or sometimes inside of our houses through our foundation walls or slabs, where it can reach dangerous levels. To be clear, it is the decay products or the alpha particles emitted as radon particles break down that is the real danger here, not the radon itself. Alpha particles that hit lung tissue generally kill the cells, which is fine as they are easily replaced, but they can sometimes damage the cell(s), potentially leading to lung cancer.
It is not an immediate danger like a fire or natural gas leak presents, but one more akin to the dangers of years of smoking. To give a picture of the health risk, living in a home with concentration level of 300 becquerels per cubic meter (Bq/mᶾ), a not at all unheard of level, is the rough equivalent to smoking a pack of cigarettes a day in terms of damage to lung tissue. As a side-note, lung-cancer risks associated with exposure to radon and to smoking are several times greater when the two are combined. As of now, roughly 16% of lung cancer deaths are attributed to radon exposure, though this is very likely an underestimate.
In Canada we measure radon concentration in becquerels per cubic meter (Bq/mᶾ), which you can divide by 37 to convert to the US unit of choice, picocuries per liter (pCi/L). The average home in Canada contains concentration levels of 41.9 (Bq/mᶾ) of radon, and the average outdoor concentration is around 10 Bq/m3 (that's right - not even outside air is completely safe).
According to a 2012 estimate, 6.9% of homes in Canada have radon levels of 200 Bq/mᶾ or more. 200 Bq/mᶾ the current actionable level (the point at which mitigation measures are recommended) set by Health Canada, lowered from 800 Bq/mᶾ in 2007. A more recent sample of homes in Guelph, Ontario revealed 18% of a random sample of 131 homes had concentrations above the actionable level. For comparison, the Environmental Protection Agency's actionable level is 148 Bq/mᶾ, and the World Health Organization's is 100 Bq/mᶾ - half that of Health Canada. A 2014 study concluded that approximately 233 lung cancer deaths per year could be prevented in Ontario if all houses with concentrations above 100 Bq/mᶾ were remediated.
There are areas that are much more prone to high radon levels than others, though concentrations can vary dramatically from house to house and even fluctuate day to day and season to season. There is truly no way to know the level of radon in a home without measuring (ideally with a long-term testing device) that specific home.
With proper certification, HVAC contractors have the opportunity to act as specialists, focusing on measurement or mitigation (or both), using some familiar products and methods and some new. Whether we're talking about new or existing, residential or commercial, it is clear that radon measurement will become an increasingly standard practice moving forward. In the US, which is years ahead of Canada on the radon scene, 33 states have already made radon measurement a requirement in each and every real estate transaction. Yes, that is a great deal of measuring.
The measurement process is fairly straight forward, though there are a number of different methods and products that can be employed. Basic measurement kits that show average concentration, such as the alpha track products from Radon Environmental Management Corporation (REMC), are relatively low in cost and simple to use; open the package and place the device in an appropriate spot on the lowest inhabited level of the house, then collect it a few months (or weeks, in the case of short-term devices) later and send it off to the lab and await the results. Digital detectors offer on-the-spot readings (usually after 48 hours of measurement), but only show averages in concentration rather than peaks.
Another type of measurement device uses air grab sampling, which allows the user to capture a sample of the air in a building and test it on the spot for fast and accurate measurements. This, however, only gives a representation of concentration levels at the moment of collection, which does not reflect the long-term average concentration levels. Long term testing gives the most accurate picture of radon levels in a building over time, and it is what is generally recommended before undertaking any mitigation. There are many who would argue, however, that an alarmingly high short term reading with similar results on a second short term test is grounds enough to proceed with mitigation, rather than needlessly spending 3 months longer in unsafe conditions while awaiting confirmation from a long-term test.
There are a few ways to mitigate a building with high radon levels, and which is appropriate really depends on the unique situation of each building. Most favoured among contractors, and recommended by the World Health Organization (WHO), is sub-slab depressurization (SSD). This is where air is drawn from under and around the slab via a pipe and inline fan and exhausted outside. Another option is to utilize the existing sump-pump hole and incorporate a sealed cover connected to the pipe and fan.
To do this in an existing home a hole must usually be cut in the slab. As time goes by it is likely builders will be required to install at least a rough-in pipe for future radon mitigation if needed. This is now mandatory by code in most of British Columbia, and is coming to other areas as well. For example it is one of the prescriptive options the City of Guelph requires of all new building permits applied for after August 31st, 2015 under its Radon Gas Mitigation Program. 3 other areas in Ontario must consider radon when building - the City of Elliot Lake, the Township of Faraday, and the Township of Hyman, all areas with a history of mining. Watch for these changes in your area.
Fresh air ventilation systems (HRVs and ERVs) can also be very effective in mitigating radon, as the process of exhausting stale, radon-filled air and diluting the air in the building with fresh air lowers overall concentration levels. This method is actually more common than sub-slab depressurization in much of Europe (which, like the US, is years ahead of us on the radon scene), though it is often seen as a sort of finishing-touch form of mitigation, secondarily to sub-slab depressurization, in North America. We may see this method gaining popularity in the future as it is less destructive to the building design, taking advantage of already existing air handling systems. When used in combination with a radostat detector it also has the benefit of reducing operating costs, as the air exchange system is only activated when rising radon levels are detected, unlike an SSD which operates continuously.
There is much more to radon, and certainly many more products and mitigation methods than I've touched on in this article. If you are interested, I would highly recommend visiting the radon section of Health Canada's website for more general information (www.hc-sc.gc.ca). The Center for Environmental Research and Technology, Inc (CERTI) now offers Canadian courses in measurement and mitigation to prepare for the corresponding Canadian Nation Radon Proficiency Program (C-NRPP) examinations (www.certi.us). For more information on radon measurement and mitigation products, as well as radon-related research, I recommend checking out BC-based REMC (radoncorp.com).