What is Radon?

Radon is a radioactive gas that comes from the natural radioactive decay of radium, which is a natural decay product of uranium. Scientifically, “radon” is known to be radon-222, the most abundant isotope of the element radon. As a noble gas, radon is colorless, odorless and chemically inert and cannot be detected by human senses. Also, since radon is not chemically reactive with most materials, it will move freely as a gas. Radon has a radiological half-life of 3.8 days, and can move substantial distances from its point of origin.

As radon-222 decays, the first four radioactive isotopes formed are polonium-218, lead-214, bismuth-214 and polonium-214. They are commonly referred to as “radon daughters” or “radon progeny. These short-lived isotopes are not gases but are chemically active solids. They are present in any environment where radon is found and, like radon, cannot be detected by human senses.

Uranium is a natural part of the earth’s crust; therefore, radium and radon are also naturally present. Since uranium and radium concentrations vary throughout the earth’s crust, radon concentrations will also vary. The amount of radon gas that escapes into the atmosphere is dependent on the depth at which it is formed and the permeability of the surrounding earth. Radon formed in the top 10 meters of soil and rocks provide the largest component of radon entering the atmosphere.

The second most important contributor to radon is emanation from groundwater. Underground radon is readily carried in groundwater and when this groundwater surfaces, most of the radon is released to the atmosphere.

Other sources of radon are very small contributors and are largely due to human activities. For example, there are radium-rich industrial by-products spread upon the earth, and sometimes construction materials are produced from raw materials that contain uranium or radium.

Why Test for Radon?

According to the Surgeon General of the United States, radon is the second leading cause of lung cancer within the USA.

Radon is estimated to cause about 21,000 lung cancer deaths per year, according to EPA’s 2003 Assessment of Risks from Radon in Homes (EPA 402-R-03-003). The numbers of deaths from other causes are taken from the Centers for Disease Control and Prevention’s 1999-2001 National Center for Injury Prevention and Control Report and 2002 National Safety Council Reports.

Only smoking causes more lung cancer deaths, but if your home has high radon levels and you smoke, then your risk of lung cancer is especially high. The Environmental Protection Agency (EPA) and the American Lung Association agree that long term exposure to elevated levels of radon pose a significant health risk to you and your family. Therefore, since radon is a colorless, odorless, and tasteless gas, the only way to determine if radon is in your home is by testing.

How Does Radon Enter The Home or Building?

Major Radon Entry Routes
  1. A Cracks in concrete slabs.
  2. Spaces behind brick veneer walls that rest on uncapped hollow-block foundations.
  3. Pores and cracks in concrete blocks.
  4. Floor-wall joints.
  5. Exposed soil, as in a sump or crawl space.
  6. Weeping (drain) tile, if drained to an open sump.
  7. Mortar joints.
  8. Loose fitting pipe penetrations.
  9. Open tops of block walls.
  10. Building materials, such as brick, concrete, rock.
  11. Well water

Radon is a naturally occurring radioactive gas produced by the breakdown of uranium in soil, rock, and water. Air pressure inside your home is usually lower than the pressure in the soil around your home’s foundation. Because of this difference in pressure, your house acts like a vacuum, drawing radon in through foundation cracks and other openings. Your home then traps the radon inside, where it can build up. Any home may have a radon problem. This means new and old homes, well-sealed and drafty homes, and homes with or without basements.

Radon may also be present in well water and can be released into the air in your home when water is used for showering and other household uses. In most cases, radon entering the home through water is a small risk compared with radon entering your home from the soil. In a small number of homes, the building materials (e.g., granite and certain concrete products) can give off radon, although building materials rarely cause radon problems by themselves. In the United States, radon gas in soils is the principal source of elevated radon levels in homes.

Nearly 1 out of every 15 homes in the U.S. is estimated to have elevated radon levels. While radon problems may be more common in some areas, any home may have a problem. The only way to know about your home is to test.