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About Disasters

Types of Disasters

Durham Region is vulnerable to a wide range of potential emergency situations. Some of these emergencies happen more frequently with localized impacts (e.g. fires, chemical spills) while others are rare but could have severe consequences on the population and the environment. Large-scale emergencies occur very rarely but we must always be prepared. In general, disasters or emergencies can be categorized into three groupings:

  • Natural-caused

    Trees fallen due to iceHazards which are caused by forces of nature (sometimes referred to as 'Acts of God'). Human activity may trigger or worsen the hazard; but the hazard ultimately is viewed as a force of nature. Natural hazards include but not limited to severe weather and floods.

  • Human-caused

    Derailed train carsHazards which result from direct human action or inaction, either intentional or unintentional. This includes hazards that arise from problems within organizational structure of a company, government etc. Human-caused hazards include chemical spills, explosions and leaks, train derailments, plane crashes, public transit crashes and multi-car pileups.

  • Technological

    Hazards which arise from the manufacture, transportation, and use of such substances as radioactive materials, chemicals, explosives, flammables, modern technology and critical infrastructure. Technological emergencies are also human-caused and can affect critical infrastructure, computer technology, power outages, telecommunications and other information technology issues.

Hazard Identification and Risk Assessment (HIRA)

The purpose of a Hazard Identification and Risk Assessment (HIRA) is to understand what risks or threats to public safety, property or the environment exist in Durham Region, and to assess their impact. Completing a HIRA forms the basis and determines the priorities for the Emergency Management Program. Understanding the risks allows for prevention, mitigation, preparedness, response to and recovery from these threats.

Hazard Identification and Risk Assessment (HIRA) Process

Derailed train cars

There are four steps to create and maintain a HIRA:

  1. Hazard Identification
  2. Risk Assessment – frequency and consequence
  3. Risk Analysis
  4. Monitor and Review annually for change in frequency and/or consequence


The Hazard Identification and Risk Assessment examined 38 potential hazards derived from provincial hazards identified by the Ontario Fire Marshal and Emergency Management, Ministry of Community Safety and Correctional Services. The level of risk for each hazard was examined, past occurrences researched and possible scenarios reviewed. The likelihood of the hazard occurring and the potential impacts of the hazard on people, property, the environment, business and finance, and critical infrastructure were examined (Provincial HIRA Workbook, 2012).

Prioritized Risks

The HIRA produced a prioritized list of risks for the Durham Region which was determined to be:

  • Transportation emergency:
    • air
    • rail
    • road
    • marine
  • Energy supply emergency
  • Severe weather:
    • snow storms and blizzard
    • ice storm
    • lightning
    • extreme temperature (heat or cold)
    • tornado, wind storm, hurricane
  • Hazardous materials incident
  • Explosion / Fire
  • Major flood
  • Human health emergency
  • Critical infrastructure failure
  • Nuclear emergency

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