Radon is a radioactive gas. It comes from the natural decay of uranium that can be found in nearly all soils. It can move up through the ground to the outside air. It can also move into your home through cracks and other holes in your foundation due to a pressure differential in your home as compared with outside. This pressure differential is the primary reason that radon will enter your home.
Nearly one out of every fifteen homes in the United States is estimated to have elevated radon levels. Elevated levels of radon gas have been found in nearly every state.
Source: EPA "A Citizen's Guide to Radon" May, 1992
As depicted in the picture above, your home is a Vacuum Cleaner, sucking in outside air to replace the air that is leaving (see Your Home's Air Demands). If you stop this sucking in of outside air through the cracks in the basement, then you will lower the radon level to that of outside the home.
How do you stop the radon from being sucked into the basement?
OPEN A WINDOW!
I know this may sound silly but it is the only sure way to reduce radon in your home. You must eliminate any pressure difference inside the home compared to the outside. You do not need a subslab suction installed in your home. In most cases they are installed incorrectly and the installers do not follow all of the EPA's requirements (including performing a back-drafting test). If you have one or are thinking of installing one, ask for the EPA procedures and tell your contractor to follow all the requirements.
However, all you may need to do is open a window.
Now I know that opening a window is not the entire answer, there are other things that need to be done. If you have a gas-forced air furnace you must seal all the connections in the basement to stop the furnace fan from putting the basement under negative pressure. A very simple test you can do is: run the furnace fan for five minutes with the basement door closed, then open the door one inch and let go. Did the basement door get sucked closed? If yes, then before you invest in anything expensive, seal all of the leaks in the ductwork with an approved aluminum tape (no gray duct tape).
"Prevention of House De-pressurization" is the most economical way to reduce the radon level in your home.
EQUALIZ-AIR can help to reduce the negative pressure in your home (basement) and can reduce the radon levels in your home.