Radon entry routes

Figures 31.3 through 31.5 illustrate typical radon entry routes found in basement, crawlspace, and slab-on-grade construction, respectively.

FIGURE 31.5 Typical radon entry routes in slab-on-grade construction. (Adapted from U.S. EPA, Radon-Resistant Construction Techniques for New Residential Construction—Technical Guidance, EPA/625/ 2-91/032, U.S. Environmental Protection Agency, Washington, DC, February 1991.)... 

Air conditioner condensate lines are sometimes installed so that they penetrate the slab to dispose of the water in the subslab area. Even when water is trapped, this can be a problem because the traps often dry up during the heating season. At this point they become radon entry routes. It is recommended that air conditioning condensate lines run to a drain that will not dry out or that a condensate pump is installed that collects the condensate and disposes of it through a water trap. Often a washing machine drain is located in a basement near enough to use it. 

Common route of radon entry to homes—seepage through the foundation. 

If possible, make the construction forgiving to later appearing cracks in the concrete. If a slab is covered with a permanently elastic material, like rubberized asphalt or bitumen, future cracks in the concrete will not automatically result in a route of entry for soil radon. 

These effects depend upon the nature of the radioactive material, its route of entry and concentration in a particular tissue, and due mainly to cr or p particles. Lung cancer has been observed in miners following inhalation of radon, and severe anaemia and bone tumour following ingestion of radium in luminising dial painters. 

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