ISO 11665-1:2012

ISO 11665-1:2012 outlines guidance for measuring radon-222 activity concentration and the potential alpha energy concentration of its short-lived decay products in the air.
The measurement methods fall into three categories:

spot measurement methods;
continuous measurement methods;
integrated measurement methods.

ISO 11665-1:2012 provides several methods commonly used for measuring radon-222 and its short-lived decay products in air.
ISO 11665-1:2012 also provides guidance on the determination of the inherent uncertainty linked to the measurement methods described in its different parts.