Officials Surprised by High Radon Levels

June 20, 2016

The Chronicle Journal reported recently that officials were surprised to find 16 percent of homes tested in Thunder Bay had high radon levels, and exceeded Health Canada standards. Radon gas is a known carcinogen, causing lung cancer in those exposed to high levels.

Health Canada advises that any indoor air environment measuring over 200 Becquerels per cubic metre, Bq/c3, poses an unacceptable risk to those who breathe the contaminated air. The average number of homes across Canada testing above the 200 Bq/m3 level is just 6.9 percent, with Ontario homes averaging 4.6 percent.

Thunder Bay’s McIntyre ward presented numbers of particular concern, finding that 43 percent of homes there contained elevated levels of the dangerous gas. Neebing ward reported 30 percent in the elevated range, Red River ward reported 15 percent, Current River ward reported 13 percent, Northwood ward reported five percent, and McKellar ward reported two percent. Westfort ward reported finding no homes with elevated radon gas levels.

Lee Sieswerda, manager of environmental health at the Thunder Bay District Health Unit, expressed surprise at the broad range of percentages, adding that additional study is needed to understand why there is such variation in measurement levels.

Radon is a natural product resulting from the breakdown of uranium in soil, rocks, and water. As radon gas filters up through the soil, escaping to the surface of the earth, it seeps into homes and buildings through foundations, cracks, and openings. If allowed to accumulate in a closed environment, the gas levels become dangerous, posing a health risk to all who breathe the indoor air.

Sieswarda noted that homes built before 1945, before the Second World War, have low levels of radon. He cautioned some homeowners, however, explaining that, “It escalates to much higher levels in homes built between the 1990s and early 2000s.”  Very new homes, Sieswarda advised, have relatively low levels of radon due to built-in systems.

Chief building official with the City of Thunder Bay Desmond Stolz attributes the improvement of new homes to recently implemented Ontario building codes for new structures. Stolz explains, “Right now we are requiring all new houses to have an enhanced radon barrier below the floor slab, which would include a polyurethane sheet which is sealed. We are requiring all penetrations to be sealed that come through the floor and we are also asking for an exhaust pipe to be built below the floor that will all for depressurization of the area if necessary.”

Testing is important, with follow up mitigation costs usually ranging from $500 to $3,000. Fixes can be quite simple and inexpensive, patching holes or cracks. Some homes require the gas to be released from underneath the home and redirected outdoors with a fan. These units are an easy install, requiring less than two days for completion.

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