Excerpt from:

The Consumer’s Guide to Radon Reduction

            Radon is a naturally occurring radioactive gas produced by the breakdown of uranium in soil, rock and water.  Air pressure inside your home is usually lower than pressure in the soil around your home’s foundation.  Because of this difference in pressure, your house acts like a vacuum, drawing Radon in through foundation cracks and other openings.  Radon can also be present in well water, but in the United States, radon gas in soil is the principal source of elevated radon levels in homes.

            The Surgeon General has warned that Radon is the second leading cause of lung cancer in the U.S.  Along with the EPA, he recommends testing for Radon and reducing Radon in homes that have levels of 4 picocuries per liter or higher. 

            The EPA recommends that you have a qualified radon mitigation contractor test and fix your home because lowering radon levels requires specific technical knowledge and skills.  Without proper equipment and training, you could increase your radon level or create other potential hazards.

             Since Radon gas is both colorless and odorless, testing is the only way to determine if there is a high concentration within a building or dwelling.  Testing with EPA approved continuous monitoring devices provide the quickest results, usually in as little as 48 hours.  Other approved options include charcoal canister and alpha track detector tests which can be done over varied periods from one week to one year, and provide accurate, dependable test results.  Many hardware manufacturers offer tests which can be purchased by consumers then deployed in the home, following the instructions provided.   Results will take longer depending on exposure intervals, shipping and lab turnaround times.   State and local health departments also can provide inexpensive testing kits and often absorb lab fees; check with these agencies for details.   Your local certified Radon professional can arrange for testing with any of the approved methods and will be familiar with their advantages and disadvantages.