Why Test for Radon
Radon is an odorless, colorless gas that is harmful to humans. Yet many homes and buildings have high levels of radon in them without the owners knowing it. The U.S. Environmental Detection Agency and U.S. surgeon general recommend that all floors below the third be tested for radon. Most homes will be fine, and a simple test will prove it.
Choice of Radon Test
Radon is measured in Picocuries per liter of air, or pCi/L. If you get a reading of 4 pCi/L or higher, you may have a radon problem. There are two types of tests done to determine this level. Short-term testing takes 2 to 90 days depending on the type of device used. Long-term testing takes longer than 90 days.
Most tests are short term. However, these tests can't give you a good year-round average measurement of the radon in your home. But they can give you an indication that there might be a problem. Windows and exterior doors should be kept closed as much as possible during the test. With tests lasting only two to three days, you should keep your windows and doors closed for 12 hours before the test as well and don't conduct these tests during storms or high winds. Put the test kit in a room that is used regularly (except for the kitchen or bathroom), 20 inches above the floor and where it won't be disturbed. Leave the kit out for the specified time and then seal the kit and send it to the lab. You should get the results a couple weeks later.
Long-term testing is done for longer than 90 days. Alpha track testing and electrets detectors are the most common types of tests done this way (though some types can be short term). This type of testing will give you a better reading of what your home's average radon level is as opposed to short-term testing.
The most common way to test for radon is with an activated charcoal test kit. The charcoal collects radon atoms from the air that can be counted in a laboratory later. This is an inexpensive test and one that is easy to do yourself. About 95 percent of all radon testing is done this way.
Alpha Track Device
Alpha track devices work in a similar way to charcoal test kits. Alpha track devices are special pieces of plastic that are marked when hit by alpha particles in radon. This can be counted in a laboratory later. This is also an easy test to do yourself and relatively inexpensive.
An electret has a plastic disc that contains an electric charge. It is normally only used by professional radon inspectors because of the cost of the analysis equipment and the expertise needed to operate electrets.
Continuous Radon Monitors
A continuous radon monitor is also used by professionals. It measures radon over two days to complete the test for real estate transactions. There is a wide variety of equipment that can measure radon in this way.