How Does Radon Mitigation Work?

You’ve done your research about radon testing. Now you know that carcinogenic radon is a hazard present in many Ottawa residences and that testing is important to determine the level of radon in your own home.

However, in your research, you keep seeing radon mitigation mentioned as a solution. How does mitigation work, and how does it prevent high radon levels? And what’s the connection between radon mitigation and radon testing? Do you need both?

When Do I Need Radon Mitigation?

Radon testing and radon mitigation are the basic steps in the process of eliminating unacceptable levels of this dangerous gas and protecting your family. Radon testing is essential to measure radon in a house; however, it is not designed to remove radon. You will need radon mitigation as a follow-up when testing reveals elevated levels, according to these Health Canada guidelines:

  • Under 200 Bq/m3: acceptable amount of radon, no remediation required (although some homeowners will opt for radon mitigation even at this level, as Health Canada states that there is “no safe level of radon”)
  • 200 to 600 Bq/m3: high, action required within 2 years
  • 600 Bq/m3 or above: extremely high, action required within the year

There are 2 types of radon testing: short and long term. Often the short term testing — which takes 7 days — is performed first to give a general indication of radon concentration in a dwelling. If the radon seems to fall within the unacceptable range, long term testing — for 3 to 5 months — may be necessary to track average levels over time.

Types Of Radon Mitigation

Active Soil Depressurization

ASD is the most popular type of radon mitigation. It may be installed in your home’s interior, exterior, or slab. A Health Canada study reports an impressive 90.7 percent average reduction in radon levels using this method.


Interior Active Soil Depressurization is a radon mitigation system commonly installed in a basement or attached garage. As part of a sealed system, radon gas either moves up through your home toward a fan located in the attic or to an exit point in one of your sidewalls, paired with a basement fan. This second method is simpler and less expensive to retrofit. In either case, the radon fan proceeds to expel radon safely outdoors. All you’ll need to do is occasionally check a monitor to ensure everything is in good working order.


Exterior Active Soil Depressurization functions very similarly to Interior. 

The goal is still to draw radon gas out of your home and release it harmlessly into the air. The main difference is that the pipes are installed on the exterior of the house, and the fan is placed at ground level. Here the advantage is that the radon mitigation installer will not have to work around your home’s interior layout.


Slab Active Soil Depressurization is suitable for houses built atop a slab-on-grade foundation. Initially, a hole 10-15 cm in diameter is drilled into the slab. After concrete dust and dirt are cleared out of the hole, a PVC pipe is installed leading to your roofline. This pipe will be the conduit that directs radon gas from your foundation level and expels it above the roof.

Crawlspace Sub-Membrane Depressurization

Sub-Membrane Depressurization is the best system for a house built over a crawl space which has a floor of dirt or gravel. The floor is sealed with a heavy plastic membrane. Then pipes and a radon fan are installed to vent radon gas outside the home, just as with the preceding methods.

Radon mitigation system

Radon Testing and Mitigation Specialists

Are you concerned about radon in Ottawa? Check radon levels in your home with Out Of This World’s reliable professional radon testing services. You have the option to book 7-day radon testing  or 3-month radon testing. Our team includes C-NRPP trained and certified radon mitigation specialists. Ask about the right radon mitigation system to protect your family.

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