How often is indoor radon a problem?

Nearly one out of every 15 homes has a radon level the EPA considers to be elevated—4 pCi/L or greater. The U.S. average radon-in-air level in single family homes is 1.3 pCi/L. The problem is significantly more severe in the Chicago-land area. Nearly 1 in every 4 homes in DuPage and Will counties screened in 2006 were found to have radon levels at 4 pCi/L or greater. Half the homes screened in DeKalb, Kendall, and Kane counties also showed dangerous levels of in-air radon.  Because most people spend as much as 90 percent of their time indoors, indoor exposure to radon is an important concern.

What is the “safe” level of radon in my home?

The EPA states that any radon exposure carries some risk; no level of radon exposure is safe. However, the EPA recommends homes be fixed if an occupant’s exposure will average 4 picocuries per liter (pCi/L) or higher.

How does radon get into a building?

Most indoor radon comes into the building from the soil or rock beneath it. Radon and other gases rise through the soil and get trapped under the building. Air pressure inside homes is usually lower than the pressure in the soil. Therefore, the lower pressure of the building draws gases through floors and walls and into the building. Most of the gas moves through cracks and other openings. Once inside, the radon can become trapped and concentrated.

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Openings which commonly allow easy flow of the gases in include the following:

  1. Cracks in solid floors
  2. Construction Joints
  3. Cracks in walls
  4. Gaps in suspended floors Cavities in walls
  5. Gaps around service pipes
  6. Cavities inside walls
  7. The water supply

Radon may also be dissolved in water, particularly well water. After coming from a faucet, about one ten thousandth of the radon in water is typically released into the air. The more radon there is in the water, the more it can contribute to the indoor radon level.

Trace amounts of uranium are sometimes incorporated into materials used in construction. These include, but are not limited to concrete, brick, granite, and drywall. Though these materials have the potential to produce radon, they are rarely the main cause of an elevated radon level in a building.

Outdoor air that is drawn into a building can also contribute to the indoor radon level. The average outdoor air level is about 0.4 pCi/L, but it can be higher in some areas.

While radon problems may be more common in some geographic areas, any home may have an elevated radon level. New and old homes, well-sealed and drafty homes, and homes with or without basements can have a problem. Homes below the third floor of a multi-family building are particularly at risk.

Click the link to see Illinois Radon Levels by County or use the provided table below.

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