What does Bq/m³ mean?
Becquerels per cubic metre. One becquerel is one radioactive breakdown per second, so 200 Bq/m³ means 200 radon atoms breaking down every second in each cubic metre of air. Outdoor air averages about 15.
Specialty · Radon Testing · Radon Map
My Radon Map of Southern New Brunswick
Six years of my own radon tests, placed on one map. It shows where I've been and what my monitor recorded. It isn't a rating of any area, and a reading near you says nothing about your home. The only way to know your home's level is to test it.
Tests62
Communities18
Years2020 to 2026
What Radon Is and How It Gets In
Radon is a radioactive gas that comes from uranium breaking down naturally in soil and rock. You can't see it, smell it or taste it. Outdoors it thins out in the open air. Indoors it can build up, because a house draws in air from the ground beneath it.
- Crack in the floor
- Gap around a pipe
- Sump pit
- Floor drain
- Wall crack
Radon, from uranium slowly breaking down in the soil and rock. The dashed arrow is warm air rising, which draws it in.
Illustration only. A home’s radon level is confirmed by testing.
What a homeowner can do
Start by measuring your home’s radon level. The options below run from simple upkeep to a dedicated radon system; flip a switch to see how each one works. The right approach depends on your home and its test result.
- 1
Floor drain Simple upkeep
A drain trap that holds water lets the floor drain work and limits soil gas coming up through it.
- 2
Cracks and gaps Sealing work
Seal the cracks, joints and gaps around pipes you can reach. Sealing alone is not a complete fix.
- 3
Sump pit Sump cover
An airtight lid seals the opening between the sump pit and the basement while the pump and drainage keep working.
- 4
Ventilation Ventilation work
A balanced heat recovery ventilator (HRV) swaps indoor air for fresh outdoor air. Existing ventilation can be checked and rebalanced.
- 5
Mitigation system Most effective
A dedicated fan draws soil gas from under the floor and vents it outside. A C-NRPP certified mitigation professional chooses the approach.
- 6
Radon monitor Measure the result
Testing before and after a change shows whether it worked. A monitor measures radon; it does not remove it.
Building new? Confirm with your builder that the radon rough-in the building code requires is in place. Test after you move in, and again after any major renovation.
Where I've Tested
Tap a town or a county to see what I found there, or play the journey to watch the map fill in year by year. Places with fewer than 5 tests are pooled so no result is tied to them.
Bigger circle, more tests there Fewer than 5 tests A circle marks a place I tested, not a reading of the ground
Every Reading, One Dot Each
Each dot is one test, placed by its result in becquerels per cubic metre (Bq/m³). 9 of my 62 tests recorded 200 Bq/m³ or higher during the test. Homes close together can read very differently, so a nearby number can't tell you about your own home.
Screening, 4 days to under 7 Short-term, 7 days to under 91 Long-term, 91 days or more
What One Home's Monitor Recorded, Hour by Hour
My monitor logs radon, temperature and air pressure every hour. Two real tests show how much a reading moves on its own, which is why a short test is an indication and a long-term test is the one to decide on.
When the air pressure drops
Radon (Bq/m³, 7-hour rolling average)Air pressure (hPa)
In the first day the air pressure dropped and the radon reading climbed. Over the next day the pressure rose about 20 hPa and the reading fell back. Lower pressure outside can let a house draw a little more soil gas in. This is what one home did; it says nothing about another.
Higher overnight, lower by evening
Average for each hour of the day, compared with this home's overall average
Over 33 days this home read highest in the early morning and lowest in the evening, on average. A test that only caught part of that rhythm could land high or low, which is why longer tests give a steadier answer.
How I Measure
Every test on this map was set up the same careful way.
- The monitor - An Airthings Corentium Pro continuous monitor, calibrated, recording every hour.
- Where it goes - The lowest lived-in level, in the breathing zone (0.8 to 2 m up), away from walls, vents, kitchens, bathrooms and sumps.
- The house - For short and screening tests, closed-house conditions: windows and outside doors shut, big fans off, fireplace off unless it's the main heat. For a long-term test, the household lives normally.
- Movement - The monitor logs motion, and I check that log for any sign it was moved.
- Credentials - Certified with C-NRPP (Canadian National Radon Proficiency Program): measurement ID 201606CRT, laboratory ID CAL201639. Member of CARST.
What This Map Is Not
- Not a risk rating - It does not rate any town or county.
- Not a prediction - Two houses on the same street can read very differently.
- Not a yearly average - Most of these are short tests, which are an indication only. A long-term test is the one Health Canada bases a decision on.
- Not every home - It's the 62 tests I've done, shared without names or addresses.
Questions People Ask
What is Health Canada's guideline?
200 Bq/m³, based on a long-term test. Health Canada asks for at least 91 days of that test to fall in the heating season. When a long-term result is 200 or higher, Health Canada advises reducing it within 1 year, and sooner if the level is higher.
Screening, short-term or long-term: what's the difference?
A screening test runs 4 days to under 7 and is usually done during a home purchase. A short-term test runs 7 days to under 91. A short test describes the days it ran. To compare a home with the guideline, Health Canada uses a long-term test with at least 91 days in the heating season. My 2020 to 2022 short tests followed the rules then: a 2-day minimum, and no separate screening class.
Why does winter testing read higher?
From October 1 to April 30 the house is shut tight and warm air rising inside pulls soil gas in at the foundation. A summer test, with windows opening and less pull, tends to read lower.