Single Test Option, Continuous Radon Monitors (CRM): The most accurate, fastest and tamper proof radon detection device currently available. This is considered an active testing method. The CRM continuously reads the air in the test area for radon gas and records the level hourly. The machines also incorporate systems, such as motion sensors, that detect test interference. The recorded data is displayed numerical and graphically on a report for the entire test period. Undoubtedly the most precise, reliable and informative method for radon testing. View an actual CRM report.
Electret Ion Chamber is a passive device. Inside the monitor is an electronic field that detects alpha particles. This method is just as accurate as CRMs. However they do not posses any type of tamper detection to indicate test interference. Nor are they capable of giving hourly readings or other information that CRMs are able to provide. In spite of these short comings Electet Ion Chambers are a good second choice to CRM testing.
Simultaneous Test Option, Charcoal Canisters, Charcoal Liquid Scintillation Devices: This is considered a passive testing method and a quite simple means for detecting radon. These devices are not nearly as accurate as a continuous radon monitor or electret ion chamber, especially the open face (canister) type. They tend to be biased towards the last 12-24 hours of exposure. Radon gas is adsorbed by the charcoal in the device. After the exposure period is complete the detector is sent to a laboratory to determine the concentration. The results are averaged for the two devices and given as a numeric value. Many factors may influence the result, most notable moisture in the test area. Most likely one of the most widely used tests and arguably the least accurate. View an actual charcoal canister report.
How do you choose: What does this mean for the consumer wishing to test for radon? Besides the differences already pointed out, the other factor to consider is the cost. Generally continuous radon monitor testing will cost slightly more than other types of testing. You will have to make a decision based on your desire to have the most accurate test available and what your budget will allow. We recommend that you educate your self on radon and then shop for the best testing service.