Radon is a radioactive gas that comes from uranium naturally present in the Earth's crust. Radon is found in the soil, everywhere on the Earth's surface. The amount of radon in the soil can vary significantly from one location to another. Radon can also be found in groundwater.

Radon can infiltrate buildings, especially through foundations. It can sometimes accumulate and reach concentrations that can pose a health risk. Since it is a gas that has no smell, taste, or color, it is impossible to detect it with the senses.

Radon enters the lungs with the air we breathe. Major international health organizations and agencies have recognized radon as a carcinogen. It emits radioactive radiation that can, in the long term, cause lung cancer.

Radon is the second leading cause of lung cancer, after smoking. It is also the leading cause of cancer among non-smokers. In Quebec, 10 to 16% of lung cancer deaths are associated with radon. This represents more than 1000 deaths per year. Among these deaths:

• 60% occur in smokers;
• 30% in former smokers;
• 10% in non-smokers.

The risk of lung cancer linked to radon increases with:

• radon concentration: the more a person is exposed to a high concentration of radon, the greater their risk of cancer;
• duration of exposure to radon: the risk of cancer increases for a person exposed to radon for several decades;
• smoking: smokers exposed to radon are more likely to get lung cancer than non-smokers.

Radon does not cause :

• respiratory disorders, such as chronic bronchitis and emphysema;
• allergies;
• asthma;
• birth defects.

Source: Natural Resources Canada  

Radon mainly accumulates in the lowest and least ventilated rooms of a building, such as the basement. The concentration of radon in a home's indoor air can depend on several factors:

• the concentration of uranium and radon in the soil;
• the climate;
• ventilation of the premises;
• the airtightness and insulation of the house;
• negative pressure, i.e., when the air pressure is lower inside the building than outside. This pressure difference causes the dwelling to act like a vacuum cleaner. Radon can then infiltrate through cracks and other entry points that are in contact with the ground.

The only way to know if there is radon in a home is to measure it.

To determine the radon concentration in your home, you need to measure it with a dosimeter. It is recommended to take this measurement for a period of at least 3 months and to perform the radon measurement during winter. You can measure the radon concentration in your home yourself or use the services of a professional.

Do not rely on test results from a neighboring house or other dwellings in your area. Indeed, radon concentrations can vary greatly from one house to another, even if they are very close to each other.

To measure the radon concentration in your home yourself, you must obtain a dosimeter and use it according to the manufacturer's instructions. For an Alpha type dosimeter, you will need to spend approximately $45 for the purchase and $10 to $20 for its shipment to a certified laboratory. A total of about $65, and you will have to wait 5 to 6 weeks for the results. Gaz Radon Québec offers a quick results retrieval option thanks to a device with an ionization chamber and electret. The result will be known the day after the detector is delivered to our laboratory. Gaz Radon Québec offers this for the modest sum of $100, including handling fees. 

To obtain an Alpha type dosimeter, you can:

• order it on the Quebec Lung Association  website, which offers certified dosimeters approved by Health Canada;
• consult the CAA Quebec Habitation  website, which provides information on how to obtain a dosimeter;
• purchase a radon air analysis kit at some hardware stores.

To obtain a list of certified radon measurement professionals in Quebec, you can use the search tool of the Canadian National Radon Proficiency Program  (C-NRPP). This certification program is recognized by Health Canada and the Quebec Ministry of Health and Social Services.

Radon is measured in becquerels per cubic meter of air (Bq/m³).

There is a guideline in Canada that states the maximum radon concentration not to exceed in a home is 200 Bq/m³. Generally, radon concentrations are not very high in homes in Quebec. The average radon concentration in basements is around 35 Bq/m³. However, concentrations can sometimes reach very high levels, up to over 1,000 Bq/m³.

Individual protection measures

If you smoke, the first thing to do to protect yourself from radon-induced lung cancer is to quit smoking. This is the fastest and least expensive way to reduce the risk of lung cancer associated with radon. Indeed, a person exposed to both tobacco smoke and radon significantly increases this risk.

Corrective measures for your residence

Health Canada recommends taking corrective measures when the annual average radon concentration exceeds 200 Bq/m³ in occupied areas of a home. If this is the case in your home, you must take action, whether you are a smoker or not.

The recommended timeframe for making corrections depends on the average radon concentration in your home:

• if the concentration exceeds 600 Bq/m³, you should make corrections within less than one year;

• if the concentration is between 200 Bq/m³ and 600 Bq/m³, you should make corrections within less than 2 years.

You will get better results by applying more than one corrective measure. For example, you can:

• seal foundation cracks;
• seal openings in contact with the ground;
• ensure sumps are covered and vented to the outside;
• improve ventilation in your home, particularly in the basement.

If radon concentrations in the dwelling are very high, these measures may not be sufficient, as they do not completely prevent radon infiltration. In this case, you need to call a qualified contractor. They will install a system that removes radon present under the foundations before it enters the habitable areas of the building.

Health Canada recommends that people taking corrective measures try to reduce radon concentrations to the lowest possible level. This is why it is recommended to re-measure radon concentrations after applying corrective methods, to verify their effectiveness.

Several specialized companies can help you reduce radon concentration and infiltration in your home. It is very important to deal with a certified company. You can consult the list of these companies on the website of the Canadian National Radon Proficiency Program  (C-NRPP) from Health Canada. Gaz Radon Québec is a certified company. 

Measures for new constructions

When building a new home, you can ask your contractor to install the necessary infrastructure for low-cost radon mitigation measures in the home. Conduct a radon test as soon as possible. If mitigation measures are needed, the existing infrastructure greatly facilitates and simplifies the work and reduces the costs associated with such work. Here too, Gaz Radon Québec can help you implement appropriate mitigation measures for your building. 

Sources for this article;

https://www.quebec.ca/habitation-et-logement/milieu-de-vie-sain/radon-domiciliaire