First, stay calm. A high radon reading is important, but it is not an immediate emergency and it does not mean that your home cannot be made safer. Radon risk builds through long-term exposure, and proven mitigation systems can reduce even very high levels.
The next step is to make sure the reading is meaningful. Check the device, where it was placed, and how long it has been testing. If the result appears reliable and is approaching or above Health Canada’s guideline of 200 Bq/m³, speak with a C-NRPP-certified professional about your options.
1. Check what device produced the reading
Not every radon monitor sold online has demonstrated that it measures accurately. Before relying on the result, identify the manufacturer and model.
Health Canada strongly recommends using a device that has passed C-NRPP performance testing. C-NRPP maintains lists of approved consumer electronic radon monitors, professional electronic radon monitors, and passive test devices.
If the monitor is an unfamiliar or unlisted product, the reading may need to be confirmed with an approved device before making a final decision.
See Health Canada’s guide to approved radon measurement devices.
2. Make sure the device is in the right location
A monitor beside a sump pit, exposed foundation crack, furnace, window, or air vent may not represent the air people normally breathe.
Health Canada recommends testing on the lowest lived-in level of the home, in a room where someone spends an average of at least four hours per day. Appropriate rooms may include a bedroom, office, family room, playroom, or living room.
The device should be:
- At least 30 cm above the floor
- At least 30 cm away from walls
- At least 1 metre away from windows, exterior doors, and air vents
- Away from direct sunlight, high humidity, and strong air currents
- Away from sumps, exposed cracks, crawlspaces, and other direct radon entry points
- Somewhere it will not be moved or disturbed
Mechanical rooms, bathrooms, kitchens, laundry rooms, and storage rooms are generally not appropriate locations for a decision-making test.
3. Look at how long you have been testing
A few hours or one day on a digital monitor is only an early snapshot. Radon can change considerably from hour to hour, day to day, and season to season.
If a homeowner contacts ATMOS after only a day of testing, we will usually suggest leaving an approved monitor in the correct location and continuing to collect data. A week or two can provide a better preliminary indication than a single day. If the average remains several hundred Bq/m³ over that period, it is reasonable to begin speaking with a mitigation professional while continuing to monitor.
However, a one- or two-week digital reading is still not the same as an estimate of annual exposure. Health Canada recommends testing for 3 to 12 months, with a minimum of 91 days during the heating season, when making a mitigation decision based on the Canadian guideline.
The longer and more representative the test, the more confidently it can be interpreted.
4. Understand what the number means
Canada’s radon guideline is based on the long-term average in a normally occupied area of the home:
- Below 200 Bq/m³: Below the Canadian action level, although no radon exposure is considered completely risk-free.
- Approaching 200 Bq/m³: Consider the test duration, season, device accuracy, and measurement uncertainty. Continuing to monitor or discussing the result with a professional may be appropriate.
- Above 200 Bq/m³: Health Canada recommends taking corrective action. Its current guidance recommends mitigating within one year and acting sooner as the level increases.
- Several hundred or more: Treat the result seriously, confirm that the measurement is reliable, and begin discussing mitigation rather than ignoring it.
The amount of time spent in the tested space matters. A basement bedroom, home office, family room, or children’s play area can represent many hours of exposure every week.
Higher numbers justify faster attention, but fear does not lower radon. A calm, informed plan does.
5. What should you do while you continue testing or wait for mitigation?
If you are still conducting a long-term test intended to estimate normal exposure:
- Leave the device in the correct location.
- Do not move or reset it.
- Continue living normally.
- Do not deliberately change window, ventilation, furnace, or air-conditioning habits simply to lower the displayed reading.
Health Canada recommends that residents maintain their normal lifestyle during a long-term test so the result reflects normal living conditions.
If high radon has already been established and mitigation is scheduled, opening windows may temporarily lower the level when weather permits. It is not a permanent solution, and it will affect any test being conducted at the time. Radon generally begins accumulating again after the windows are closed.
6. What does not permanently fix high radon?
Running the furnace or air conditioner does not remove the source of radon. In most homes, it primarily circulates air and can move radon from the basement to other levels.
Bathroom fans and other exhaust fans are also not dependable radon solutions. Exhausting indoor air can change the pressure inside the home, and any temporary reduction ends when the fan is turned off.
Opening windows can dilute radon temporarily, but it is impractical during a Calgary winter and does not stop soil gas from entering the home.
Sealing visible cracks and sump openings is an important part of professional mitigation, but sealing alone is rarely a dependable solution for a home with significantly elevated radon. An active system addresses the pressure beneath the foundation and intercepts the gas before it enters the living space.
7. What happens when you contact ATMOS?
We begin by asking questions about the measurement and the home, including:
- The radon level and how long you have been testing
- The manufacturer and model of the device
- Where the device was placed
- The age and location of the home
- Whether the home is detached, attached, or a duplex
- Whether the basement is finished or unfinished
- Whether there is a radon rough-in, sump pump, covered sump, visible cracking, crawlspace, or HRV
If the home has not been properly tested, we can help arrange testing and explain how the device should be placed and left undisturbed.
If the home has an elevated result, we arrange an in-person mitigation estimate. During the visit, we inspect the basement, identify accessible radon entry points, discuss the proposed suction point and pipe route, explain the modifications to the home, and provide a clear scope and price.
If the homeowner proceeds, most standard installations take approximately five to eight hours. Once the work is complete, we pressure-test the system and verify that it is operating properly. When the homeowner has a digital monitor, we normally check in within about 24 hours and again over the following days to see how the readings are responding.
ATMOS guarantees that systems we install will reduce the home’s radon level below 75 Bq/m³.
High radon is fixable
Even a very high radon level does not mean that a home is beyond repair. Almost every Alberta home can be mitigated, although the system design may differ depending on the foundation, slab, sump, crawlspace, and layout.
Every completed ATMOS mitigation system to date has reduced the home’s radon level by at least 80 percent. Many of our customers see post-mitigation readings in the range of approximately 15 to 40 Bq/m³, although every home and season are different.
The technology is well established. A properly designed active soil depressurization system runs continuously, requires little routine attention, and can provide reliable reduction for many years. Homeowners should periodically check the system’s manometer and continue testing; Health Canada recommends retesting a home with an active mitigation system every five years.
You do not need to panic, and you do not need to solve the problem alone. The important thing is to use reliable information, understand the result, and take the appropriate next step.