Updated: Dec 4, 2019
Winter in Canada …
a time for skiing, skating, sliding, tubing, snowshoeing, snowmobiling, polar bear dips and chalets. It’s also a time when levels of indoor radon concentration can significantly increase (watch for our upcoming Radon 101 post!). Radon which would normally escape from the ground into the atmosphere, is trapped by snow cover and frozen ground. Building doors and windows are usually kept closed – reducing natural ventilation. The requirement for indoor heating in occupied buildings both warms the soil under the structure’s foundation and creates a temperature differential between the surrounding soil and the indoor air. This results in the Stack Effect – drawing radon from the soil into the building.
The following graph illustrates typical seasonal patterns for all countries which experience seasonal temperature changes; 360 day continuous radon monitor (CRM), 91 day and 7+ day tests track directly with building operational response to outdoor weather conditions – in general, seasonal weather patterns repeat every year (for each local climate) and hotter indoor air results in significant air pressure differences with outdoor air to drive radon entry.
Radon activity concentration & temperature difference