Radon Testing Methods
Since radon gas is colorless, odorless and tasteless, one can only measure radon levels using one of the following radon testing methods:
- Activated Charcoal Canisters
- Alpha Track Detection Kits
- Electret-Passive Environment Radon Monitor
- Safety Siren Radon Detectors
Activated Charcoal Canisters
Radon in indoor air is measured using a canister of activated charcoal that adsorbs the radon gas. The device consists of a scintillation vial containing activated charcoal, a diffusion barrier and a desiccant agent. A passive diffusion method for the determination of radon concentration is used to minimize the effects of environmental humidity and extends the useful exposure time to up to 7 days. The advantages of this method are its simplicity, low cost, low detection limit, the total automatization of the measurement and its total independence of humidity to measure in a wide range of radon concentrations. Activated Charcoal Canisters must be sent in to a lab for measurements where the radon levels are typically measured using a sodium iodide detector.
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Alpha Track Detection Kits
An alpha track detector operates on a very different principle than the charcoal-based short term radon test kit and provides a much better indication of your home's long term average radon level. Inside the unit is a piece of film that records the impacts (tracks) of alpha particles produced by the decay of radon and its decay by-product, polonium. When the detector is analyzed, the foil is chemically treated to enlarge the alpha tracks, which are counted on an automated system. The alpha track radon test kit remains in your home for more than 90 days, allowing you to measure the radon level under normal living conditions. An alpha track detector takes into account all the changes in weather that occur during the radon gas test period, as well as the changes in the way the house is used under differing weather conditions.
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Safety Siren Radon Detectors
A safety siren radon detector, some times called radon gas monitor, conveniently allow short and long term readings of the radon levels. With this radon detector, the homeowner can monitor radon levels both with short-term and long-term averages. The radon gas monitor must be plugged in for 48 hours before the first reading is displayed. A reading of more than 4 pCi/L is a clear indication that you must take action to mitigate the levels of radon within your home. In Canada and elsewhere the measurement unit may by Bq/m3. Do not get confused, 1 pCi/L = 37 Bq/m3 and a reading of more that 148 Bq/m3 calls for action. Although radon gas is almost 8 times heavier than air, do not make the false assumption that it will just stay in your basement and your will be safe, because the HVAC system does an amazing job at pushing it to all levels of your home. Radon kills slowly and the effects can only be seen after 5 to 25 years, depending on the amount of radiation you are being exposed to. You definitely must do more than just hope for the best.
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Electret-Passive Environment Radon Monitor
These radon gas monitoring kits comprise an electret, a chamber, an electret reader and the software for data interpretation. Electret-Passive Environment Radon Monitor are not affected by varying concentration, temperature or humidity. Radon gas diffuses through the filtered inlet into the monitor chamber until the concentration of radon inside the chamber is the same as that in the room. Radiation emitted by the decay of the radon and the decay products formed inside the chamber ionizes the air. The positively charged electret attracts the negative ions generated by the radiation in the chamber resulting in a net decrease of the electret voltage. Positive ions go to the wall of the chamber and get dissipated. This voltage decrease of the electret is proportional to the radon concentration and the time of the exposure.
