It is sometimes useful to have a measure of the total radiation dose to groups of people or a whole population. The quantity used to express this total is the collective effective dose. It is obtained by adding, for all exposed people, the effective dose that each person in that group or population has received from the radiation source of interest. For example, the effective dose from all sources of radiation is, on average, 2.8 mSv in a year. Since the world population is about 6000 millions, the annual collective effective dose to the whole population is the Product of these two numbers which is about 17000 000 man Sievert, symbol man Sv.
It is common for effective dose to be abbreviated to dose and collective effective dose to collective dose.