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Refinery plant
Seveso establishments are establishments that produce, process, treat or store dangerous substances, e.g. refineries, petrochemical plants, chemical plants, oil depots or storage sites for explosives.

The name Seveso refers to a town in the north of Italy. On 10 July 1976 an explosion occurred in a chemical plant near this town. After the explosion, a dioxin cloud spread in the area.

Seveso establishments are divided into upper-tier establishments and lower-tier establishments, depending on the nature and quantity of dangerous substances present in the establishment. The tier of the establishment determines the legal obligations it has to meet.



  • Walk away from the incident. It is best to walk perpendicular to the direction of the wind.
  • Shelter in the nearest building.
    • Go inside and stay inside. Sheltering is the best way to protect yourself. Stay inside until you are informed that it is safe again.
    • Close windows, doors and turn off ventilation systems. Preferably stay in a central area, on the ground floor. Walls and ceilings offer better protection than windows.
    • Listen to the government's recommendations. Inform yourself about the right measures.
  • Use text messages or the Internet to communicate. Keep the telephone network clear so people can call the emergency services.
  • In some cases, you will need to evacuate. Follow the instructions of the emergency services. Do not do this on your own initiative.


  • A chemical accident can have a toxic impact on, for example, vegetables from the garden or drinking water. Follow the government's instructions.

Impact and probability

Incident at a Seveso establishment. Impact: low impact. Probability: likely. Industrial pollution. Impact: low impact. Probability: likely. In 2018, the National Crisis Center coordinated a large-scale risk assessment for Belgium for the period 2018-2023. Several experts assessed various risks based on their probability and their impact on people, society, the environment and the economy.

For the risk of 'incident at a Seveso establishment', the analysis is:

  • Impact: low impact
  • Probability: likely

For the risk of 'industrial pollution', the analysis is:

  • Impact: low impact
  • Probability: likely 

Read more about this analysis and what these charts mean.

What do the authorities do?

Since 1982 there has been a European Seveso Directive to reduce the risk of industrial accidents. The Directive has a dual purpose:

  1. to avoid serious accidents involving dangerous substances
  2. to limit the consequences of such accidents for people and the environment

This Directive imposes preventive safety measures, which include:

  • obligations on the operator of the establishment to
    • take all necessary measures to prevent major accidents or to mitigate their consequences
    • draw up and implement a prevention policy
    • draw up and implement an internal emergency plan
  • inspection programmes. Each region has an inspection team made up of regional and federal inspectors. They regularly check Seveso establishments during proactive inspections and follow-up inspections.
  • urban planning. Each Seveso establishment has to obtain an environmental permit before starting its operation.
  • information to citizens. On seveso.be you can find all necessary information about major accident hazards. Every five years there is also an information campaign.
  • organisation of assistance. The provincial governors are responsible for drawing up the special emergency and intervention plan for upper-tier establishments under the Seveso Directive.

In case of a chemical accident, this special emergency and intervention plan enters into force.