What are the risks of having radon in my house ?

It is well known that lung cancer is a deadly cancer, mostly associated with smoking. However, smoking is not the only cause of the lung cancer. Exposure to radon is the second cause of lung cancer. In Québec, around 10% of lung cancer deaths are associated with radon exposure. Radon is associated with over 600 lung cancer deaths each year.

It’s a naturally occurring radioactive gas that comes from the decay of uranium in the earth’s crust. It is present everywhere on the surface but the emission is not uniform. The radon can pass through the house, particularly through cracks and other entry points in the basement. Radon is colorless, odorless and tasteless. It’s impossible to detect with our senses. The unit of measurement for radon is the becquerel per cubic meter of air (Bq/m3).

Radon is not very present in outdoor air (1 to 10 Bq/m3) because it is greatly diluted. However, it can infiltrate public and residential buildings. In the indoor air of homes, radon can be present in larger quantities. Typically, radon levels range from 30 to 100 Bq/m3. However, in some cases, concentrations can reach very high levels (over 1000 Bq/m3), even exceeding the Health Canada guideline of 200 Bq/m3. The average radon concentration in basements has been estimated to be around 35 Bq/m3 (annual geometric mean).  Since radon is heavier than air, it tends to accumulate in the lowest and least ventilated rooms in the home (e.g., in the basement).  Depending on the location, radon is found in different concentrations in the ground. Some rock formations may contain more uranium and thus emit more radon.

In general, radon can enter in a house through differents ways:

• cracks

• sumps

• crawl spaces 

• openings around exhaust ducts

• chimney effect

Presence of radon inside a house is due to severals circumstances:

• high concentration of radon in the soil (importance of the source)

• poor ventilation of the premises (ventilation rate)

• the high airtightness of the house

• negative pressure in the building envelope

What are the risks associated with radon ?

It is mainly the risk of lung cancer that drives the vigilance towards the radon in homes. Radon is classified as a “proven human carcinogen” by the International Agency for Research on Cancer (IARC).

As a gas, radon penetrates in the lung with the air and attacks the bronchial tubes.

The first protection measure for the health against lung cancer is not smoking. Indeed, people that are exposed at the same time to smoke and radon have a higher risk of developing lung cancer. It’s a synergic effect. Among the lung cancer deaths due to a radon exposure, 60% of them happened in smokers, 30% on old smokers and 10% in non-smokers.

We all can measure the concentration of radon in our house and act to reduce the level of radon.

Health Canada recognizes the National Radon Competency Program in Canada. A list of Canadian certified radon measurement professionals can be found on their website. To know the concentration of radon present in your home, it is necessary to perform a test using a device designed for this purpose. You cannot rely on the result of the neighbor’s house or the average of the neighbourhood, because there is often a significant difference from one house to another.

Since radon concentrations can vary from hour to hour and season to season, it is advisable to test over several months to obtain a more accurate measurement. The measured values are generally higher in winter than in summer.

Without going into the details of the various techniques, there are several works that can sufficiently mitigate radon.

– Sealing cracks in slabs

– Installation of watertight covers on sumps

– Installation of depressurization systems

– Installing a ventilation system

Take care of yourself and others in your home and test to see if you have radon in your home!