My service involves placing an active radon monitor and retrieving results after a minimum period of 48 hours, in accordance with the Radon Industry Licensing Act and Title 32 Illinois Administrative Code 422.
I only use top-quality Airthings Corentium Pro monitors, which I typically place in the lowest lived-in level of a home, out of the way in a corner, and on top of a stable camera tripod.
After the testing period, I give immediate results in a detailed report, including a formal signed statement on whether or not mitigation is recommended.