How to assess people's exposure: counting rules?
Hazard study: identification of external interests to be protected

There is a general principle for counting people potentially exposed to an incident, which is to take into account the most unfavorable situation (Order of September 29, 2005, "potentially exposed people"). The worst case must appear.

This means not counting in weighted averages, but in maximum simultaneous occupancy (e.g. traffic jams, schools during school hours).

At the date of the ED, building zones should not be counted, unless the operator is aware of a specific project. On the other hand, it should be pointed out in the file that the site may no longer be compatible with its environment if new buildings are erected.

The next step is :

• determine the surface area of effect zones leaving the site for each type of effect c f. Summarize risks