What testing protocol should be followed?
The purpose of the measurements, as well as budget and time constraints, dictate the protocol used. However, the EPA and the Surgeon General recommend testing all homes below the third floor for radon. the EPA recommends that for homes, initial measurements be short-term tests placed in the lowest lived-in level.
The protocol for measurements made for the purpose of assessing the need for mitigation (reducing the radon level) is found in the EPA publication, A Citizen's Guide to Radon. Additional guidance is provided in the ANSI-AARST MAH Protocol for Conducting Measurements of Radon and Radon Decay Products in Homes.
Protocols for measurements made for real estate transactions are somewhat different. They are described in the EPA document, Home Buyer's and Seller's Guide to Radon. Additional guidance is provided in the ANSI-AARST MAH Protocol for Conducting Measurements of Radon and Radon Decay Products in Homes.
Where should home testing be done?
The EPA recommends that testing be done in the lowest level of the home suitable for occupancy. This typically represents an area where greatest radon level may occur. Ideally, the test should be conducted in a regularly used room on that level, such as a living room, playroom, den, or bedroom. Avoid testing in a kitchen, bathroom, laundry room, or hallway. High humidity and drafty conditions can bias results from some test devices. Do not disturb the devices while they are sampling. Doing so may alter their results, so they should be placed out-of-the-way.
If the lowest occupied level is not used much, consider also testing a higher-use area. This may help you to better estimate your long-term exposure.
Because most indoor radon comes from naturally occurring radon in the soil, high indoor levels are more likely to exist below the third floor. This is why the EPA recommends testing all homes below the third floor. In some cases, high radon levels have been found at or above the third floor, due to radon movement through elevators or other air shafts in the building. If you are concerned about this possibility, you may decide to test for radon.
More information on site selection can be found in the ANSI-AARST MAH Protocol for Conducting Measurements of Radon and Radon Decay Products in Homes.
