Environmental health in emergencies

Deliberate events

Wounded persons and emergency medical team

A deliberate event is an act (or threat) involving the intentional release of hazardous substances to cause harm. Hazardous substances include chemicals, biological agents and radiological materials.

Deliberate events cover a wide spectrum of intent and public health impact. They can be on a small scale, for example, contaminating a few samples of a product to extort money from a retailer. They can also be on a large scale, such as the deliberate release of biological, chemical or radionuclear material for terrorist purposes.

One famous deliberate event happened in 1995 when members of the Aum Shinrikyo sect deliberately released sarin nerve gas into the Tokyo subway.

Key resources

Deliberate chemical release: FAQs

Initial clinical management of patients exposed to chemical weapons - Interim guidance document

Information sheets

Warning signs of a chemical release
What to do in case of a chemical release


Basic equipment for decontamination
Decontamination steps
Initial management flowchart
Signs and symptoms of exposure

Other WHO resources

Related sites