8.4.6 Choosing The Appropriate Quantity

The quantity selected for an assessment must match the applicable exposure limit and the conditions under which exposure occurs. The decision depends on frequency, exposure duration, source geometry, field region, distance from the source, spatial distribution, and whether whole-body or localized exposure is being assessed.

A practical assessment commonly begins with the applicable external reference-level quantities. Compliance with the relevant reference level demonstrates compliance with the corresponding basic restriction. It is not necessary to determine both quantities.

If a reference level is exceeded, that does not by itself demonstrate noncompliance. A more detailed assessment may show that the corresponding basic restriction is still satisfied. Similarly, where reference levels are not applicable to the field region or exposure configuration, the relevant dosimetric quantity must be assessed directly using an appropriate laboratory or computational method.