What-Is-Radon-Featured-Image-Mike-Holmes Advice Make It Right
What-Is-Radon-Featured-Image-Mike-Holmes Advice Make It Right

What Is Radon Gas In A House?

By Mike Holmes

Mike’s Advice / Home Safety & Maintenance

Wednesday, July 27th, 2022 @ 6:19am

What Is Radon Gas?

Uranium is everywhere in the ground and in all kinds of soil, and when it starts to break down it creates a radioactive gas that is odourless, colourless, and tasteless. This gas is radon. It is the leading cause of lung cancer for non-smokers.

When this gas is released into the atmosphere, it gets diluted. But if it finds its way into your home it can accumulate, which is when it can become dangerous. This is why we make sure all of our projects have been tested for radon.

Is Radon Gas Dangerous?

Being exposed to high doses of radon over a long period of time is a major health risk. According to Health Canada, radon is linked to about 16 percent of all lung cancer deaths in Canada. That makes it the second leading cause of lung cancer; first for non-smokers.

Being a smoker significantly increases a person’s risk of developing lung cancer if they are also exposed to elevated levels of radon. For example, people who are only exposed to radon have a 1 in 20 chance of developing lung cancer whereas those who are also smokers have a 1 in 3 chance.


It’s estimated that 3,200 people die every year in Canada due to radon. In the US it’s about 20,000!


How Does Radon Come Into The House?

  1. Soil
  2. Windows
  3. Cracks in walls & floors
  4. Loose pipe fittings & support posts
  5. Floor drains & sump pumps
  6. Wall & floor joints
  7. Groundwater

Radon can seep into a home through pipes, windows, sumps, unfinished floors, cracks in foundation walls, and floors-even through foundation walls. Remember, concrete is porous and radon is a gas. That means it can penetrate through the tiny holes in a home’s foundation walls.


Measuring Radon in Canada

Radon is measured in becquerels, which is a unit used to measure radioactive concentration. The Canadian guideline for radon dictates that a home should not contain more than 200 Bq/m3 or 200 units of becquerels per cubic meter. Before 2007, the national guideline for radon was 800 Bq/m3.

Between 2009 and 2010, Health Canada did a cross-country survey that revealed about 7 percent of Canadians are living in homes with radon levels above the guideline.

The survey also revealed that different parts of the country have different levels of radon. For example, Manitoba, New Brunswick, Saskatchewan, and the Yukon had the highest percentages of radon, whereas Nunavut and Prince Edward Island had the lowest.

Testing for Radon


Regardless of location, the only way to know if a home contains dangerous levels of radon is to test for it. One house can have radon levels next to zero while the house next door can have levels that are off the charts.

Radon levels also fluctuate depending on the weather, humidity, the home’s construction, and the time of year. For example, winter is the best time to test for radon because windows and doors tend to be kept shut during most of the season, which allows any toxins in the home to build up. This provides a good reading on indoor air quality and a home’s exposure to radon.

Mike Holmes and Radon Tester - How to mitigate radon

The only way to know if you have radon is to test for it.

Did You Know?

Some granite countertops have been known to emit radon. That’s because granite is mined from the ground where uranium and radon are also found.

Homeowners can purchase radon test kits themselves from Radon Environmental Management, but make sure you follow the instructions. For example, radon detectors must be placed a certain distance away from interior walls, exterior walls, below the ceiling, and above the ground. Do it the wrong way and the test results can be compromised.

Homeowners are encouraged to hire a professional to test for radon, such as a home inspector certified by the Canadian National Radon Proficiency Program (C-NRPP), in order to ensure accurate test results. You can also hire a home inspector who can test your home for radon.

Short & Long-Term Testing for Radon

There are short-term and long-term tests available. A short-term test can last anywhere between 2 – 7 days, whereas long-term testing can last as long as 365 days.

Due to the fluctuations in radon levels, long-term testing provides a more accurate indication of a home’s average year-round radon levels. For this reason Health Canada recommends long-term testing.

Test your home for Radon

Radon Victoria

The Victoria™ Radon Alarm

These are some great options for testing:

  • Victoria TM Alarm detects elevated levels.
  • Radtrak2® is suitable for 90 days-365 day testing
  • Rapidos® provides short-term measurement detection with long-term benefits
  • Airwell for testing your water

RELATED: What Is The Best Radon Test Kit?

Getting Rid of Radon Gas


Reducing radon levels in a home can cost anywhere between $500 and $3,000. If your test results show an elevated level, look into these mitigation options:

  • Radostat attaches to your ERV/HRV.
  • Radon Guard & Block for new construction. One of my Holmes Approved partners installed this system. Read about the project in BC here.
  • Airwell tackles quality issues with your water. You can read about my experience with Airwell on Holmes+Holmes here.

Mike Holmes and Radon Mitigation System - Radon Fan

Did You Know?

Ontario Tarion now covers radon remediation for the full 7 years of coverage. The push is for more new-home warranty programs to do the same.


If your home requires radon mitigation, make sure you hire a contractor who is certified by the Canadian National Radon Proficiency Program (C-NRPP) and who has plenty of experience reducing radon levels in residential construction.

We spend most of our time indoors, so it is very important that we think about our indoor air quality. I recommend that every homeowner test their air quality, whether they are buying, renovating, or simply living in a home. Read why your home’s indoor air quality is so important.



Radon Fans and Better Indoor Air Quality

How to: Mitigate Radon in Your Home in 100 Days (Or Less)

7 FAQs about Radon and Radon Mitigation System 

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