The effects of a Seveso accident can be felt at varying distances. Those distances make it possible to define possible impact zones in which there can be consequences for the population and the environment.
These zones vary, according to the risk and its potential extent, between dozens of meters and several kilometres for some installations.
These are the zones in which harmful effects on man can occur, and in which protection actions can be taken depending on the concrete situation.
Within the framework of the Seveso II European Directive, different zones have been identified:
- Vigilance zone: zone where the effects of the accident can affect sensitive persons or worry non-informed persons.
- Risk zone: zone where the effects of the accident can have serious, direct or indirect, immediate or long-term consequences.
- Zone of immediate danger: zone where the effects of the accident can have irreversible or lethal consequences in case of exposure even for a short period.
Emergency planning zones
On the basis of the identified risks (explosion, toxic release, fire), emergency planning zones have been determined, in which measures for the protection of the population are worked out by the different authorities and intervention services.
In an emergency situation, the emergency planning zones are suitable for determining an intervention zone adapted to the reality of the situation (e.g. wind direction,…). This is the zone in which the measures are actually implemented.