Where Does Radon Come From?  Radon gas comes from the radioactive disintegration of uranium decay products. Uranium is found underground in igneous rock and in the soil. As it decays, the gas radon is formed and moves upward through the soil until it becomes trapped beneath structures such as basement or cement slabs.  Because soil may come from the weathering of igneous rock such as granite, and igneous rock usually contains uranium, most soils contain uranium.  Well water may also be a source of radon. Since radon is soluble in water, it is more likely to be a problem in ground water rather than surface water where it escapes into the air.  Therefore problems may arise in private wells or public water supply systems that use ground water. If you have a private well, test the radon level in your water with our radon-in-water test kit. If radon is present in your water, showering, cooking, and using dishwashers and washing machines can release radon gas into the air. Generally each 10,000 pCi/L in water contributes 1 pCi/L to indoor air.  Back 

Can radon be increased in your home through showering, cooking, and using dishwashers and washing machines?  Yes it can, but it would only make up a very small percentage of the radon in the air.  For every 10,000 pCi/L in water only 1 pCi/L would be released into the air.  (Read the paragraph above.)   Back

Can Building Materials Contain Radon?  Yes they can.  The term granite radon refers to the fact that radon may come from granite.  Radon in granite building materials could lead to additional amounts of radon in a house.  Granite tile floors, granite countertops, granite tile walls,  may contain uranium.  When uranium and some of its byproducts decay, radon gas is formed.  Other types of igneous rocks or igneous rock forming minerals used as or in building materials may also release radon.   Back  

How does Radon get in the house?  Radon is one of the decay products formed during one of the steps through the radioactive decay series of uranium.  Soil and rock (such as granite) at different depths and in different areas of the country may be abundant in uranium.  Granite floor tiles and granite counter tops may contain radon.  Since radon is only 2.68 angstroms in diameter, it easily passes through most paints and building materials such as wood paneling, most insulation, sheetrock, concrete block, mortar, buffalo board and tarpaper (felt). Radon is highly radioactive (emits alpha, beta, and gamma particles and forms other elements (daughter products). Inside buildings radon can reach dangerous levels.  Since radon is a gas it naturally rises to the surface and easily permeates through any entry points in the house from the ground.  Any house in an area with a radon problem may contain radon.  Houses with basements, without basements, with crawl spaces, or sitting on slabs, may have radon problems.  Radon gas also gets into the house through household use of water.  Back 

1. Cracks in solid floors
2. Construction joints
3. Cracks in walls
4. Gaps in suspended floors
5. Gaps around service pipes
6. Cavities inside walls
7. The water supply (5% of the radon in the house may be due to bathing, showering, cooking, washing clothes, etc.)

Radon can come into the house as a result of the wind blowing outside and creating a negative pressure within the house with respect to the pressure in the ground.  Fans, gas or fuel burning furnaces, wood stoves, fireplaces, low atmospheric pressure, etc. may cause a negative pressure within the house.  Since the pressure in the soil is greater then that within the house, it tends to force soil gases into the house through any of those areas mentioned above.  It may also come in through sump holes.  Back to Radon Info Page or Back to FAQ'S