The greatest risk of radon exposure is in buildings that are airtight, insufficiently ventilated, and have cracks in the foundation. Radon from the soil can leak into the house and due to the lack of ventilation, will stay in the house.
Radon test kits can be purchased fairly inexpensively and in some cases are free. Visit the EPA’s radon website or call the radon hotline at 1-800-SOSRADON (1-800-767-7236) for more information on where to get a radon test kit.
Most kits include a collector that a homeowner hangs in the lowest level of the house for 2-7 days. This collector is then sent to a laboratory for analysis. There are also long-term kits that measure the radon levels for one year before being sent for analysis.
An open-land test kit can test radon emissions from the land and is useful in finding concentrations of radon before construction begins so the contractors know to take steps to prevent the radon from entering the house.
Because radon levels fluctuate naturally due to the weather and other conditions, the initial test may or may not be accurate. If the first test shows high levels, it is advisable to repeat the test before undertaking expensive renovations.
The EPA recommends that preventive measures be taken if the radon level in a home is greater than 4 pCi/L (pico Curies per Liter). Because there is no known safe level of exposure to radon, homeowners with levels between 2 and 4 pCi/L should also consider taking steps to decrease the amount of radon in their homes.
Because the half-life of radon is only 3.8 days, once the source is removed or the home is protected, the danger from radon will be greatly reduced within a few weeks.
Because inadequate ventilation can lead to high radon concentrations, one way to mitigate radon levels is to improve the home’s ventilation by installing a positive-pressure ventilation system that pulls fresh air from outdoors into the heating and cooling system.
Another way is through sub-slab depressurization (also called active soil depressurization or soil suction). This removes the radon from the soil before it enters the house using a vent system that pulls radon from beneath the house and vents it to the outside, away from windows and any other intake areas. The radon is diluted in the outside air and quickly reaches safe levels.
You can also seal the basement or foundation to prevent radon from entering the house. However, the EPA recommends using sealing in connection with one of the other methods for best results.