Collective effective dose
The quantity collective effective dose (S) of a group of exposed persons i = 1, 2,… who each receive an effective dose Ei, is defined as:S = ∑ Ei
The corresponding unity is manSievert (manSv).
By tracking the collective effective dose of the group through a number of years, one gets an impression of the development of radiation protection practices. However, if the individual dose for the 10 billion people on this planet each increases by 1 nSv, the product 10 manSv is not meaningful.