One of the key findings of our work so far, is that newer Canadian houses have higher radon relative to older properties.
As you can see in the infographic below, the number of Canadian houses that exceed 200 Bq/m3 radon has doubled since the middle of the 20th century. Alarmingly, our research indicates that this trend is continuing to worsen.
Building features that our research has found to correspond to higher radon, include:
1. Building size and height
Our data demonstrate that:
- Larger footprints (i.e. larger square footage) have higher average radon.
- Taller ceilings have the highest average radon.
- Properties with fewer storeys (floors), have the highest average radon. This means that a one storey property (bungalow) is predicted to have higher radon levels than a three storey property. See point #4 below.
2. Building air dynamics:
Buildings can operate under negative air pressure at lower levels, drawing radon up through the foundations in an active way (essentially, sucking it up into the house). Once radon is inside, it can be concentrated if the building air dynamics are not balanced between the amount of fresh air being brought inside (whether by passive or mechanical means), and the amount of stale air leaving the home via the roof or other vents. We find that:
- Properties with newer windows had higher average radon compared to older windows.
- Roof insulation with high R values (a measure of an insulating materials ability to prevent heat loss) was associated with the highest average radon levels.
- Interestingly, properties with heat recovery ventilators (HRV) had the highest average radon, contrary to what would be expected and is now an active subject we are studying.
3. Building age:
The age of a property is also a predictor of radon levels. We find that:
- Newer properties are twice as likely to have the high average radon compared to older properties. This is associated with constructing our new properties more air tight, larger and taller.
4. Building residential type:
While no type of residential building is radon proof, there were some differences between property types.
- Out of all the residential types tested, the Canadian bungalow with its large footprint, high ceilings and fewest dilution points had the highest average radon. We would like to emphasize that this does not mean that other property types are low in radon. This just means that while all Canadian properties types were found to have higher radon compared to other regions, the Canadian bungalow was the highest.