There’s a scene in “The Princess Bride” where the villain Vizzini offers his enemy an invisible, odorless and tasteless poison. While it's meant for a laugh, he could have just as easily been talking about radon gas. 

       You can’t see, smell or taste radon, yet exposure to the gas is known to increase your risk of lung cancer. In fact, the Surgeon General has warned that radon is the second-leading cause of lung cancer in the United States today after smoking.

       Radon comes from the natural (radioactive) breakdown of uranium in soil, rock and water and enters into the air you breathe by penetrating your home through cracks in the foundation. It can be discovered in all parts of the country and can cause a dangerously high indoor radon level in any home. According to the Environmental Protection Agency, roughly one out of every 15 homes in the U.S. is estimated to have elevated radon levels.  

Therefore, it’s a wise  move to include a radon test as part of your inspection, and allow enough time (usually 3 days) to get the results and negotiate remediation with the seller, if necessary.   Your home inspector will usually do a “short-term” radon test to make sure the levels of radon are below the 4.0 pCi/L level target by the U.S. EPA.  The World Health Organization actually uses a lower target--under 3.0 pCi/L.

        Elevated radon levels can be remedied with a radon-reduction system, which can reduce the gas by up to 99% percent and can cost less than $1,000.   One system eliminates the radon by utilizing "soil suction"--a pipe is installed directly into the earth under the home, and carries the radon up and out of the house without the gas ever entering the home; if this method is not possible, a system which increases air exchange rates (ventilation) inside the home can be utilized, which reduces the pCi/L level by diluting the radon.

Buyers and sellers should be smart about radon. Every new home should be tested after occupancy, even if it was built radon-resistant or with a radon reducing system installed.  For more information about radon, consult the EPA's "Home Buyer's and Seller's Guide to Radon":   http://www.epa.gov/radon/pubs/hmbyguid.html