There are several methods that a contractor can use to lower the radon levels in your home.  Some techniques prevent radon from entering your home with others reduce the level after it has entered.  They type of radon reduction system that will work best for your home will depend on the foundation design of your home. (i.e. basement, slab-on-grade, crawlspace).

In houses with basement or slab-on-grade foundations, radon is usually reduced by one of four types of soil suction: subslab suction, drain tile suction, sump hole suction, or block wall suction.

The most common and usually the most reliable is the subslab suction technique.  Basically suction pipes are inserted through the floor slab into the soil underneath.  A radon vent fan connected to the suction pipe draws the radon gas from below the house and releases it into the outdoor air while creating a vacuum beneath the slab.  For a more detailed description of this an the other types of radon reduction techniques I recommend you download the EPA’s “Consumer’s Guide to Radon Reduction”

All radon reduction techniques typically include sealing cracks and other openings in the foundation.  Sealing cracks helps limit the flow of radon into the home thereby improving the effectiveness of the other systems in place.  Please note that the EPA does not recommend the use of sealing alone to reduce radon. Tests have shown this is not an effective way to reduce radon levels consistently.

You can help in the reduction of radon levels in your home by opening windows, doors and vents on the lower floors in your home.  This mixes the outdoor and indoor air together effectively reducing radon levels in the home.  This should be regarded only as a temporary radon reduction technique as radon levels will return to the previous levels when the doors and windows are closed not to mention the increased cost of re-conditioning the air.

Where to get more information about radon.

US Environmental Protection Agency
Colorado Department of Public Health and Environment
Center for Environmental Research and Technology Inc.
National Cancer Institute
American Journal of Epidemiology