One of the most common radon test types is the activated carbon test. Using this technique, a small canister of activated charcoal is placed in the lowest livable area of a home or commercial building (the basement, if you have one) for several days. After exposure, the canister is sealed and sent to a laboratory for analysis. Charcoal canister tests help you determine the radon concentration present at the time of the test. Other test devices include electronic continuous radon monitors (CRM’s), which can be used to detect and document radon levels on an hourly basis. This type of test is especially valuable when you are involved in purchasing a home and want to prevent tampering with the test device. Certain monitors can also be used to locate primary radon entry points.