AirthingsCorentium Home Radon Detector 223 Portable, Lightweight, Easy-to-Use, (3) AAA Battery Operated, USA Version, pCi/L

how often does the tester need to be calibrated and how much does it cost to calibrate

Are we positive the readings are accurate? I have now tested the first floor of the house and am getting a reading of 7.5 pCi/l.

what is the shortest amount of time you can do a test with this device? a home inspection last only a few hours..will it have to be left over night?

I see there are air holes in the back, so if it is placed against a surface, won't it impede the airflow into the detector?