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Deliberate events


    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 consequences. They can be on a small scale, for example, contaminating a few samples of a product/food to extort money from a retailer. They can also be on a large scale, such as the deliberate release of biological, chemical or radio-nuclear material by terrorists to kill or injure humans or animals, contaminate food or water, or destroy crops or severely damage the environment. Criminals have used explosive, flammable and toxic chemicals in their deliberate attacks, often with transportation systems as their main target. In case of conflict or war, chemical or nuclear plants can also be deliberately targeted with huge consequences if damaged or destroyed. Deliberate events can also be intentional infectious disease outbreaks within a community. 

    The development, production and use of biological and chemical weapons pose serious hazards to those who seek to use them as well as their potential victims. Their use or threatened use obliges governments both to seek to prevent such use and to prepare response plans, which should be developed as an integral part of existing national-emergency and public-health plans.


    WHO focuses on the possible public health consequences of an event, regardless of whether it is characterized as a natural or accidental event, or as a deliberate act. 

    WHO advises Member States to strengthen public health surveillance and response activities in order to be prepared for possible deliberate events, with an emphasis on: 

    • more effective national surveillance of outbreaks of illness, including alert and response systems at all levels that can detect public health events of natural, accidental, or deliberate origin; 
    • better communication between multiple sectors, including public health, animal health, water supply, food safety, nuclear safety, poison and pollution control, civil protection, law enforcement and security services;
    • improved assessments of vulnerability, and effective communication about risks and threats to both professionals and the public; 
    • preparation for handling the psychosocial consequences of the deliberate use of pathogens and substances to cause harm; and 
    • contingency plans for an enhanced response capacity by all sectors.
    WHO response

    With the occurrence of a potential, suspected or confirmed deliberate event, WHO would, upon the invitation of the affected Member State(s), work closely with the Member State government(s), other UN agencies, and other international partners as appropriate, support the event response, and assess and mitigate the public health consequences. These activities could include:

    • working with relevant international or national organizations to better characterize the nature, scope and impact of the event;
    • facilitating the public health investigation of the event, including referral to appropriate laboratories for confirmation and characterization of the substance or the pathogen;
    • offering targeted training to public health responders;
    • facilitating the identification and acquisition of necessary materials (such as personal protective equipment) appropriate to the event;
    • supporting the continued delivery of essential health services; and
    • developing guidance material specific to the pathogen or substance in question.


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