Ill. Admin. Code tit. 32, pt. 422, app B
The first step is to perform a short-term measurement* in the lowest structural areas**.
* Short-term tests may last between 2 and 90 days, most last between 2 and 7 days. Tests between seven and 90 days are usually impractical for real estate transactions but are fine for homeowners assessing their own radon situation. Examples of short-term detectors used in home environment testing include: activated charcoal canisters, charcoal liquid scintillation vials, electret chambers and continuous monitors.
** Conduct a short-term test in each of the lowest structural areas suitable for occupancy in the home. For example, if the home is a split-level building with one or more foundation types: test in the basement, in a room over the crawlspace and in a slab-on-grade room. In accordance with this protocol, measurement professionals are required to test in each of the foundation types.
Ill. Admin. Code tit. 32, pt. 422, app B