| Radon occurs naturally in all parts of the United States, and it has been estimated to cause 5,000 to 20,000 lung cancer deaths each year. Radon inhalation is second only to smoking as a cause of lung cancer. It has been estimated that nearly 1 out of every 15 homes in the United States has elevated radon levels.
Radon is a colorless and odorless radioactive gas that is produced when small amounts of uranium and radium in soil and rocks decay. Radon gas also decays into smaller radioactive particles that can be inhaled into the lungs where it can damage cells and cause lung cancer.
Radon is mainly released from solar-heating systems that use radon-emitting rocks, from uranium or phosphate mine tailings, and from soil, water and natural gas that have already been exposed to radon. The gas is naturally released in low concentrations, but it can become more concentrated inside a house, mainly as the result of a lack of ventilation and exhaust fans that help the flow of fresh air from outside.
The U.S. Environmental Protection Agency suggests that homes be tested for radon and that they have concentrations no higher than 4 picocuries per liter of air. Radon levels can be reduced by increasing air flow into the house, keeping vents open year round, and discouraging smoking indoors.
For people selling their homes, the EPA recommends that houses be tested for radon, and that radon levels be reduced, if necessary. For people buying homes, the EPA recommends obtaining radon test results in addition to information about radon reduction systems.
The EPA recommends that tests for radon in the home be conducted in the lowest level of the home that is suitable for occupancy. A "Test Checklist" is available from the EPA to aid homeowners in correctly conducting the test.
Tests for radon are classified according to two basic sampling methods used: passive and active. Passive testing devices are the easiest and least expensive to use, but are considered somewhat less accurate than active testing devices.
Passive devices, such as charcoal canisters, alpha track detectors, and charcoal liquid scintillation devices, are exposed to air in the home for a specified amount of time, then sent to a laboratory to be analyzed. Active devices, like continuous radon monitors and continuous working level monitors, continuously measure and record the amount of radon in the air, and require operation by trained testers.
Just as the type of sampling device
will affect test results, so will the length of time used for conducting the
test. The longer the period over which a sample is collected, the more
accurate that test results will be. |
