The simple answer is you test for it. Testing for radon typically consists of a device or testing kit being left inside the home for a period of time. In most cases the devices or kits need a minimum of 48 hours. From there if an electronic device was used the results are ready on the spot. If a kit was used, it's shipped off overnight to the nearest certified lab for analysis.
Radon is a invisible radioactive gas that seeps through the soil and has the potential of causing lung cancer. The EPA estimates that Radon is responsible for 21,000 deaths annually making it the second leading cause of lung cancer deaths in America. Its presence is known throughout the United States and it simply has higher levels in certain areas. Tennessee happens to be one of those areas with high levels and we encourage you to have your home tested.
When testing for Radon we use the Sun Nuclear 1027 machines. They are professionally calibrated every year and provide a very accurate hour by hour account of your radon gas levels.
Radon gas is easily mitigated. It;s so common here in Tennessee that there are many resources to help make your home safe for you and your family. If you have a crawlspace the process typically includes encapsulating the crawlspace with a few pvc pipes below that are then hooked to a special fan that simply sucks the gas out from under the encapsulation and out over the home. Slabs are slightly different but the idea is the same. In most cases they drill a hole into the slab and run the piping out just like they would with a crawlspace. Costs for radon mitigation can vary but for average situations could range from $1,000 to $2,500.