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Is Your Property Harbouring a Silent Danger? Unmask the Risk of Radon

danger of radon

For many, owning a real estate property represents stability and security. Beneath the reassuring solidity of walls and foundations, however, a hidden danger can lurk. Radon, a culprit in a significant portion of lung cancer cases, is present in homes across the country, making it a national public health concern that demands awareness and action. 

what is radon and why it is dangerous

What is Radon? 

Colourless and odourless by nature, this radioactive gas lurks unseen within the walls of our homes and workplaces. Radon originates from the decay of uranium in soil and rock. When radon escapes into the open air, it becomes diluted and poses no threat. However, in enclosed environments such as homes and offices, it can build up to high levels, creating a health hazard for residents. 


The Danger of Radon 

As radon gas decays, it forms radioactive elements that can be inhaled into the lungs. Within the lungs, radon continues to break down and releases radioactive particles that emit brief bursts of energy. This energy is absorbed by the lung tissue, damaging the lung cells. Damaged cells may lead to cancer when they reproduce. 

The Environmental Protection Agency (EPA) and the World Health Organization (WHO) report that radon comes second only to smoking as the leading cause of lung cancer. Prolonged exposure to elevated radon levels in indoor air increases the risk of developing lung cancer. The risk varies based on the concentration of radon and the duration of exposure. 

More than 3,000 Canadians die each year from lung cancer caused by radon exposure. In the US, radon is responsible for approximately 21,000 lung cancer deaths each year. 

how to detect radon

Detection of Radon 

The aim is to minimize radon levels in enclosed spaces as much as possible. Detecting radon, given its invisible and odourless characteristics, requires specialized equipment. You can purchase a portable kit to measure radon yourself. 

Multiple techniques are available for gauging radon levels in edifices, spanning from short-term to long-term evaluations. Short-term assessments, running from a few days to 90 days, offer a swift overview, whereas long-term tests, surpassing 90 days, deliver a more precise mean radon level. Typically, these tests involve placing a radon detector in the lowest inhabited part of the structure and sending it to a laboratory for analysis. 

Measurement of Radon 

In outdoor settings, radon rapidly disperses to extremely low levels. The average outdoor radon level typically falls between 5 Bq/m3 and 15 Bq/m3. However, indoor environments and poorly ventilated areas, like mines, caves, and water treatment plants, may have elevated radon concentrations. In structures such as houses, schools, and offices, radon levels can vary greatly, ranging from 10 Bq/m3 to over 10,000 Bq/m3. 

The likelihood of developing lung cancer rises approximately 16% for every 100 Bq/m3 increase in long-term average radon concentration. This suggests a linear dose-response relationship, where the likelihood of lung cancer rises proportionately with greater radon exposure. 

Health Canada recommends a radon action guideline of 200 Bq/m3. However, different jurisdictions have established different thresholds. The World Health Organization (WHO) sets a national annual average residential radon concentration reference level at 100 Bq/m3, with a maximum limit of 300 Bq/m3 under specific country-specific conditions. In the United States, the limit stands at 148 Bq/m3. 

Radon levels exceeding 200 Bq/m3 require mitigation by a C-NRPP-certified professional. Consider radon reduction even for lower levels. 


how radon gets inside the buildings

How Radon Can Enter Inside the Building 

The pressure inside a building is usually lower than the pressure in the ground outside. This pressure difference creates a suction effect, pulling air and gases (including radon) from the soil into the enclosed space through any openings near the foundation. Even new and well-built homes can have these openings. 

The path of least resistance for radon can vary depending on your foundation. While cracks in basements are a common culprit, less common foundations like slabs, stone, or treated wood may have their own unique entry points. Unfortunately, some pathways for radon might be hidden and difficult to access, regardless of the foundation type. 


factors to affect the amount of radon

Factors to Affect the Amount of Radon 

Most enclosed spaces, if not all, have some level of radon gas. Even buildings/facilities right next to each other can have wildly different radon levels. 

The amount of radon in a closed space will depend on various factors: 

  • Soil characteristics: Radon levels in soil can swing wildly. It depends on how much uranium is present, and some soils, like sand, are like highways for radon gas compared to the stopper clay soils can be. 

  • Construction type: The design and type of your property can create a welcome mat (or not!) for radon. Properties with more contact with the soil and larger or more numerous openings are more susceptible to radon entry. 

  • Foundation condition: Lots of cracks and holes in the foundation make it easier for radon to get inside. 

  • Occupant lifestyle: Opening windows, using fans, and fireplaces can change the air pressure inside the property compared to the ground. This pressure difference can draw radon gas in and affect how much fresh air enters the space. 

  • Weather: The weather outside can affect how much radon gets inside the property. Factors like temperature, wind, air pressure, and rain can all play a part. 

mitigation of radon


Lowering radon levels requires a careful approach. If your property exceeds the guideline level, Health Canada recommends consulting C-NRPP-certified professionals who are trained to perform safe and effective radon mitigation. 

Some of the common radon exposure mitigation include: 

  • Sub-Slab Depressurization: This is the most common method performed by C-NRPP-certified professionals. Radon mitigation systems utilize a network of pipes installed through the foundation floor slab. A powerful fan continuously draws radon gas from beneath your property and vents it outdoors for safe dilution. This system also reverses the pressure difference between your property and the soil, significantly reducing the amount of radon entering the foundation. 

  • Sump-hole depressurization: Active sump-hole depressurization can be a cost-effective way to address radon. This system utilizes the existing sump pit. The sump is sealed and becomes the location for a radon suction pipe, which acts like a vacuum, pulling harmful radon gas away from your property. However, if your basement drain connects to the sump, a special water trap is needed to prevent indoor air from entering the sump. 

  • Drainage system depressurization: For properties with block wall foundations and existing drain tiles, drainage system depressurization is a technique worth exploring for radon mitigation. This method utilizes suction applied directly to these tiles to remove radon gas. The key is for the drain tiles to form a complete loop around the foundation for best results. Partial coverage with drain tiles might not be as effective. 

  • Sealing Cracks and Openings: While not a standalone solution, sealing cracks and openings where radon might enter your property can help lower levels. These weak spots include open sumps, floor drains, the joint where the floor meets the wall, exposed soil around the foundation, and any hollow spaces within concrete block walls. This method is best used alongside other techniques for a comprehensive radon mitigation plan. 

  • Heat Recovery Ventilation (HRV): Heat or Energy Recovery Ventilators (HRV), also known as Energy Recovery Ventilators (ERV), can be a solution, but they work best in specific situations. These systems increase ventilation by bringing in fresh air while pre-heating or cooling it with outgoing air. This can help reduce radon levels, but balanced airflow is essential to avoid creating a pressure difference that could draw in more radon. Ventilation is most effective in spaces that are already airtight and have low natural ventilation. 

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