This part of ISO 11665 describes integrated measurement methods for short-lived radon-222 decay products[4]. It gives indications for measuring the average potential alpha energy concentration of short-lived radon-222 decay products in the air and the conditions of use for the measuring devices.This part of ISO 11665 covers samples taken over periods varying from a few weeks to one year. This part of ISO 11665 is not applicable to systems with a maximum sampling duration of less than one week.The measurement method described is applicable to air samples with potential alpha energy concentration of short-lived radon-222 decay products greater than 10 nJ/m3 and lower than 1 000 nJ/m3.NOTE For informative purposes only, this document also addresses the case of radon-220 decay products, given the similarity in behaviour of the radon isotopes 222 and 220.