Radon Gas Blog

Radon levels during the winter, a potentially dangerous situation.

Posted by Travis Jewell on Mon, Nov 28, 2011 @ 06:05 PM

Radon in Winter


Old man winter is knocking at the door and he might be bringing radon with him. In homes that are located in cold weather environments, radon levels can be a greatly increased during colder months. This often-overlooked issue with radon gas is potentially one of radon’s greatest threats.

If you are like me, you hunker down for the cold months. When not at work, you tend to spend more time in the house enjoying a book, catching your favorite sports event or watching a movie. The house is our safe haven from the harsh weather outside. But is it really that safe? Radon levels in many homes tend to be higher during the winter months. Here are a few of the reasons why:

1.    Greater stack effect can draw more radon into the home. During the winter, stack effect tends to be greater as the 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.
2.    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 it.
3.    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. During the winter the windows are usually shut to keep the house warm which can effect the concentration of radon in the house. Note: Opening windows can have the opposite effect by increasing the home’s stack effect and therefore pulling more radon in.

Why do I think this is one of radon’s greatest threats?

I have met many people who base their home’s radon level off of one single radon test result. Often times this test was performed a long time ago and the actual test report has gone missing. Many times, the radon test was performed by the home inspector during their real estate transaction and all they were told was that they “passed.” Many people may be living with radon levels that are significantly higher than what that single radon test had told them because of factors like seasonal variations. I believe that there are too many people who are living with the false sense of safety that they have low radon levels when in reality, they could be breathing high radon throughout half of the year.

If you have tested for radon in your home using a short-term radon test kit and the results came back under the EPA action level, consider performing another radon test during the opposite season that the original was performed. The best way to understand your true radon exposure is to perform a long-term radon test that samples the air throughout all the seasons.

Most importantly, don’t think that you are safe from radon based upon the results of a single radon test that may have been performed during a time of year when radon gas levels were naturally low. If you have high radon levels during any season consider radon mitigation to reduce the levels. Radon mitigation can reduce radon levels consistantly throughout the year to eliminate any seasonal variation.

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