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Managing a Chemical Incident 


Who does what?

Response is multi-disciplinary and very much joint working.  Blue light services will deal with the initial incident and will notify UKHSA and the relevant local authority for public health (and environmental health) input.  For example, fire services would fight fires, carry out rescues, protection the environment, mass decontamination.  Police would preserve the scene of the crime, establish and maintain cordon and ambulance services would provide decontamination of causalities.    NHS primary and secondary care services would deal with causalities and wider health concerns. 


UKHSA  health protection  and local authority public health teams would be involved in the assessment of the implications of exposure to population health.   Other agencies that may be involved (depending on the nature of the incident) include Environment Agency, Food Standards Agency, Health and Safety Executive, Met Office, Media and local authorities.  


Basic Principles

Response to a chemical incident usually follow the JESIP Principles:

  1. Co-locate
  2. Communicate
  3. Co-ordinate
  4.  Joint understanding of risk
  5.  Shared situational awareness


Tiers of Command

Bronze (Operational):  

  • this is the front line control at the scene of an incident
  • each of the emergency services has its own operational responsibilities and deploys its own resources under the command of its own incident officers
  • police usually coordinate
Silver (Tactical):  

  • with more serious incidents, agencies introduce a tactical level of management at or close to the scene of the incident or in administrative offices 
Gold (Strategic):  

  • this is the second tier of management usually based in a pre-planned location with extensive communication facilities away from the scene of the incident. 


Useful Definitions

Hazard = potential source of harm or adverse health effect on a person or persons.  Hazardous materials may cause damage to skin or eyes or may enter the body via ingestion, inhalation or absorption.   Exposure may be acute or chronic and effects may be instantaneous or delayed. 

Risk =  the likelihood that a person may be harmed or suffers adverse health effects if exposed to a hazard. The terms 'Risk' and 'Hazard' are  are often used interchangeably but they are different.  

Toxin = naturally exposed toxic chemical (e.g. snake venom)
Toxicant = manmade origin (e.g. pesticides) or of natural origin if manipulated, concentrated or dispersed by humans (e.g. lead poisoning) 

Types of Chemical Incidents

  • Asbestos
  • Carbon monoxide
  • Petroleum
  • Chlorine
  • Smoke/product of combustion (e.g. tyre fires release a number of chemicals into the air)
  • CS gas
  • Ammonia
  • Mercury
  • Hydrochloric Acid
  • Sulphuric Acid


Investigating a Chemical Incident

  1. Obtain as much information as possible - who, what, where, when.   
  2. Check information - what is the chemical? (Chemical Abstract Service information if possible); what media (air, water or land? ); what is the risk to health? 
  3. Who is there?  -  HAZMAT officer? Is it a COMAH site? What organisations and individuals are involved? 
  4. How many people were exposed? Anyone hospitalised? 
  5. How big is the release? 
  6. Check CHEMET - which way is the wind blowing?
  7. Organise a meeting.  Depending on the event, this could be bronze, silver or gold.  
  8. Risk assess the pathway.  Get advice from experts (there is always an expert on different chemical or radiological hazards on call).   
  9.  Be aware of any possible land contamination (heavy metals, phenolic compounds, oil and polycyclic aromatic hydrocarbons can leach into the ground or be washed into watercourses by fire fighting water)
  10. Advise actions to protect population - decontamination, PPE and whether or not people need to be sheltered or evacuated.  (By 'sheltering', we mean "go in, stay in and tune in".  Usually the best option and  can be a better protective action than evacuation.  It can reduce exposure by a factor of 10 or by 30-50, if windows and doors are sealed (use of wet towels, newspapers).   Evacuation carries its own risks and resource implications but has been used before an incident as a precautionary measure, during an incident if there is imminent risk or prolonged exposure and after an incident if there is gross environmental contamination. )  
  11. Advise the local director of public health on the situation, causality, acute and chronic effects, population at risk and public health actions required.  
  12. Report -  environmental monitoring, biomonitoring and consider cohort/case control study.
Keep a log!  It is very important to keep good detailed and legible notes including time log, all decisions made and why.  Often there is a public inquiry or an investigation and good record keeping is a must.