How Does It Get Into My Home?

In constructing a house with a basement, a hole is dug, footings are set, and coarse gravel is usually laid down as a base for the basement slab. Then, once the basement walls have been built, the gap between the basement walls and the ground outside is filled with material that often is more permeable than the original ground. This filled gap is called a disturbed zone.

Radon moves into the disturbed zone and the gravel bed underneath from the surrounding soil. The backfill material in the disturbed zone is commonly rocks and soil from the foundation site, which also generate and release radon. The amount of radon in the disturbed zone and gravel bed depends on the amount of uranium present in the rock at the site, the type and permeability of soil surrounding the disturbed zone and underneath the gravel bed, and the soil's moisture content.

The air pressure in the ground around most houses is often greater than the air pressure inside the house. Thus, air tends to move from the disturbed zone and gravel bed into the house through openings in the house's foundation. All house foundations have openings such as cracks, utility entries, seams between foundation materials, and uncovered soil in crawl spaces and basements.

Most houses draw less than one percent of their indoor air from the soil; the remainder comes from outdoor air, which is generally quite low in radon. Houses with low indoor air pressures, poorly sealed foundations, and several entry points for soil air, however, may draw as much as 20 percent of their indoor air from the soil. Even if the soil air has only moderate levels of radon, levels inside the house may be very high. 

Test Your Home Today

Take action, test your home for radon today.  The only way to tell if you have radon is to TEST.  Testing is inexpensive and easy.  The fastest way to test for radon would be to call in a professional who offers a radon testing service.  If you choose to conduct the radon test yourself, you can find a do-it-yourself test kit at your local hardware store or a home center.  You may also call 1-800-325-1245 for a list of laboratories that sell radon kits.  These kits are very easy to use and 95% correct IF USED RIGHT.  Take the five minutes it takes to study the instructions.   Take a short-term test first.  If your result is 4 pCi/L or higher, take a follow-up test to be sure.  Follow-up with either a long-term test or a second short-term test depending on your time allowance.  If you find a high result you should have your home fixed.  Choose a radon contractor to fix your home who is state certified and/or listed in EPA's Radon Contractor Proficiency (RCP) Program.

Radon Reduction Techniques

Radon reduction systems work.  Some radon reduction systems can reduce radon levels in your home by up to 99%.  

There are several methods that a contractor can use to lower radon levels in your home.  Some techniques prevent radon from entering your home while others reduce radon levels in your home.  Some techniques prevent radon from entering your home while others reduce radon levels after it has entered it.  EPA generally recommends methods which prevent the entry of radon.  Soil suction, for example, prevents radon from entering your home by drawing the radon from below the house and venting it through a pipe, or pipes, to the air above the house where it is quickly diluted.

Any information that you may have about the construction of your house could help your contractor choose the best system.  Your contractor will perform a visual inspection of your house and design a system that considers specific features of your house.  If this inspection fails to provide enough information, the contractor will need to perform diagnostic tests to help develop the best radon reduction system for your home.  For instance, your contractor can use a "smoke gun" to find the source and direction of air movement.  A contractor can learn air flow sources and directions by watching a small amount of smoke that he or she shot into holes, drains, sumps, or along cracks.  The sources of air flow show possible radon routes.  

Another type of diagnostic test is a "soil communication test."   This test uses a vacuum cleaner and a smoke gun to determine how easily air can move from one point to another under the foundation.  by inserting a vacuum cleaner hose in one small hole and using a smoke gun in a second small hole, a contractor can see if the smoke is pulled down into the second hole by the force of the vacuum cleaner's suction.  Watching the smoke during a soil communication test helps a contractor decide if certain radon reduction systems would work well in your house.

Whether diagnostic tests are needed is decided by details specific to your house, such as the foundation design, what kind of material is under your house, and by the contractor's experience with similar houses and similar radon test results.

The cost of making repairs to reduce radon depends on how your home was built and the extent of the radon problem.  Most homes can be fixed for about the same cost as other common home repairs.