Air pressure inside homes (particularly basements) is slightly lower than in the ground creating a vacuum, which draws in radon from several feet away into the basement through openings and pores in concrete. Warm air inside homes moves upward just like inside a stack and this stack effect reduces air pressure in the basement. When the ground is soaked with rain, the bottled up radon gas in the ground moves to a warm opening such as a basement. This stack effect will cause radon inflow that will easily migrate in to the home.
The pores in concrete (such as in your basement) allow a passageway for radon gases, water vapor, and liquid water to enter the basement. Almost half of the water used in poured concrete is surplus and has to evaporate. Concrete cures and passes moisture to the surfaces creating a network of capillary-like pores.
Heavy radon gas accumulates in basements and on lower floors. According to the residential radon lung cancer study completed in Iowa, the 1st floor of a home receives 40% of its air from the basement level.
Effect of Radon Gases
Radon is carcinogenic and can cause cancer. It is estimated that 12% of all lung cancers are caused by exposure to Radon gas. It is also estimated that 15,000 to 20,000 of the 158,000 lung cancer deaths per year in the United States are caused by exposure to Radon. Many years may pass before the effects of radon are detected.
Prevent Radon Gases
Minimize the entry of radon gas into your home by sealing cracks in the foundation and along the basement walls, floors, or molding. Cover all crawl spaces with a heavy polyethylene barrier and seal it to the foundation wall. Close sump pits and floor drains.