Radon Gas – What is it?
Radon is an invisible and odorless radioactive gas is produced by the natural disintegration of radioactive heavy metals uranium and thorium, which are dispersed throughout the Earth’s crust.
Uranium and its daughter products radium and radon, are found in nearly all rocks and soils.
Most contain only 1 to 3 parts per million (ppm) of uranium, but some, like granites, dark shales, light-colored volcanic rocks, and sedimentary rocks with phosphate, may contain as much as 100 ppm. Thorium, which is even more common, also produces radium.
Radon gas naturally moves into the permeable disturbed soil and the gravel bed surrounding foundations and then, into the buildings through openings and pores in concrete. Radon from soil is by far the main source of indoor radon.
Building materials like rocks, bricks, and concrete also give off radon. They produce Radon-222 and Thoron (Radon-220), but only 0.1 – 0.3 pCi/L each in a typical basement.
Radon is soluble in water and also gets indoors by “water migration”. Water is drawn indoors by the capillary action of the pores in concrete or pushed by hydrostatic pressure (seepage).
The higher temperature and lower pressure indoors release the gas. The typical basement or slab lets in 35 or 50 ltrs of water and vapor each day. Radon from outside air also settles in basements, because it is nine times heavier than air.
In the US the target of the Radon Abatement Act is the natural level outdoors (average 0.4 pCi/L). Radon is the most potent carcinogen in our homes and buildings you cannot see radon gas and you cannot smell it or taste it. Radon is a [...]