A radon 222 traceability chain from primary standard to field detectors.

The development of a primary standard from a method for measuring the absolute activity of 222Rn has also made it possible to establish secondary standards. Detailed procedures to obtain these secondary standards are given. These standards are, in particular, adapted to the requirements of laboratories that have developed equipment for the calibration and comparison of instruments measuring the concentration of radon and its daughters. An example of the implementation of these new resources applied to the qualification of field detectors is given. The propagation of measurement uncertainties at each level (primary, secondary, test radon chamber) is described.