scope:

This part of ISO 11665 gives guidelines for estimating theradon-222 surface exhalation rate over a short period (a fewhours), at a given place, at the interface of the medium (soil,rock, laid building material, walls, etc.) and the atmosphere. Thisestimation is based on measuring the radon activity concentrationemanating from the surface under investigation and accumulated in acontainer of a known volume for a known duration. This method isestimative only, as it is difficult to quantify the influence ofmany parameters in environmental conditions. This part of ISO 11665is particularly applicable, however, in case of an investigation, asearch for sources or a comparative study of exhalation rates atthe same site. This part of ISO 11665 does not cover calibrationconditions for the rate estimation devices. The measurement methoddescribed is applicable for radon exhalation rates greater than 5mBq/m2/s. NOTE The uncertainty relating to the estimation of theresult obtained by applying this part of ISO 11665 cannot guaranteethat the true flux value is included in the uncertainty domain.