Radon Levels in the Winter

Did you know Radon levels in the winter are more extreme? Cold Weather Effect: Cold temperatures force homes to run the furnace circulating more heated air causing what is known as a “Stack Effect”. Stack effect is the natural movement of air up and through the building. The result of this stack effect is drawing in more air (thus more radon gas) from small cracks and openings in the foundation into the basement and the rest of the home.

Radon Levels in the Winter

As the temperature drops and cold air settles outside of your home, it actually increases the natural draw your home puts on the soil as the warm air is pushed up increasing the potential deadly radon gas into the home. 

Radon Levels in the Winter

Fun Fact: Often we may feel that newer homes with energy efficient windows, etc. prevent radon from entering the home.  This is not the case – the stack effect and pressure differences created from the home draws in the radon gasses – sometimes even more than older homes due to the more porous backfill required in construction.  Radon gas is present in all homes regardless of age, quality, and dwelling size. 

Hundreds of tests have proven that radon concentrations increase in the winter months largely due to the facts stated above.  With the increased radon levels in homes, our families and pets are put in additional danger. This is due to the fact that kids spend less time outdoors, windows are shut, and more time is spent in the basement. 

Details about Radon in the Winter

  • Greater stack effect can draw more radon into the home. During the winter, the stack effect tends to be greater as warm air within the house rises and escapes to the colder air outside. As air escapes, the house has to replace the air to equalize pressure. Many houses get new air through drafty doors and windows. Houses also get new air from the soil they are built upon. The air from the soil can be pulled in through cracks in the concrete, plumbing pipe penetrations, sump pump pits, floor drains, crawlspaces and any other areas that have contact with the soil. This new air that enters can contain radon gas.


  • Greater concentrations of radon can enter the home during winter months. Radon enters the home from the soil below it. But, more radon escapes through the soil around the home and dilutes into the fresh outdoor air. During winter months, in cold climates, the ground in our yards can freeze and be covered with a layer of snow. This creates a blanket effect that can trap radon in the soil around the house. Since less radon in the soil is able to escape through the frozen ground in the yard, the house may be pulling in higher concentrations of radon.


  • Closed house conditions during the winter can keep radon gas levels from being diluted by fresh air. During warmer months some dilution can occur when you open the windows to bring fresh air in. However, your windows are usually shut to keep your house warm, which can affect the concentration of radon in your house. Note: Opening windows can have the opposite effect by increasing the home’s stack effect and therefore pulling more radon in.

Test Your Home for Radon Today

The good news is that a simple, inexpensive test can help you determine whether or not you should consider a radon reduction system.  If you already have a reduction system, the EPA recommends re-testing every two years (or after any alterations to your home) – the best time to test is now when the danger of radon levels are at their highest. Order your test today.