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Chemical incident management

Chemical incident management



Chemical incidents include events in which there is unintended (or sometimes deliberate) release to the environment of chemicals with potential to cause harm to human health.  There are many such acute incidents in any year – chemical spillages, fires, release of chemicals into water systems, plumes of smoke or floods – entailing exposure of substantial numbers of people.  Fortunately, most result in comparatively modest burdens of serious health effects, but they require careful and coordinated management by health protection professionals and the emergency services.  The various phases of incident management are described below.


Key definitions and terms

Chemical incident

Any event (usually acute) in which there is, or could be, exposure of the public to chemical substances which cause, or have the potential to cause ill health.


Taking action to reduce, isolate, or remove contamination from an environment with the goal of preventing adverse effects on human health.




Chemical incidents may take a number of different forms and evolve over varying timescales from acute emergency incidents to events involving chronic contamination.  Important categories of events include: chemical spillages from fixed site or transportation sources, non-domestic fires, release of chemicals into water systems, flood events, and chronic contamination of land.

In England and Wales, in 2015 there were around 800 reported acute chemical incidents recorded, the annual number of incidents has been consistent over the last 5 years, ranging between 800-900. In 2015, 793 incidents involved one or more identified chemicals and resulted in 36 fatalities. Six percent of incidents resulted in evacuation of the nearby population. The most common type of incidents are fires (almost half – 46%), followed by spills (15%) and leakages (14%) and releases (10%). Explosions account for only 1%[1].

The chemical agents involved include products of combustion, organic and inorganic compounds, and a variety of other agents.  The most common locations are industrial and residential, followed by commercial settings and transport-related incidents.


Incident management

Public Health England

In the UK, The Centre for Radiation, Chemical and Environmental Hazards of Public Health England[2]  provides support to the National Health Service and emergency response agencies in dealing with the management and consequences of chemical incidents'.  Guidance issued by PHE divides the incident response into four phases:

  • The first few hours;
  • The first 24 hours;
  • The remainder of the management period;
  • Post incident.[3]

Key tasks in each of these phases may be divided into:

- assessment of the potential adverse risks to public health;
- communication: between relevant agencies/organisations and with the public;
- action to protect the public or to mitigate adverse health effects.

Specific actions will depend on the nature and scale of the hazard.

The first few hours

The initial stages of incident management focus on information gathering/risk assessment and precautionary actions.  Information needs to be gathered rapidly about the location and nature of the incident, the chemicals involved (their identities, quantities, chemical properties, particular dangers, toxicology data), potential human exposure (pathways of exposure, number of people already exposed, number in danger of becoming exposed, likely time course of exposures), and evidence about the contaminant concentrations and their likely dispersion into the local environment (routes of spread in all media – soil, water, air – influence of weather conditions etc).

Good communication is important between the emergency services (who are the first responders) and local authority environmental health departments, public health departments, local accident and emergency hospitals, GPs, local resilience forums[4], and other agencies.  Depending on the nature of the hazard, it may be appropriate for contact to be made with water companies, PHE, the Environment Agency, the Drinking Water Inspectorate, the Health and Safety Executive, the Foods Standards Agency etc, and to make initial contact with the press radio and television.

Consideration should be given to forming an incident control team with members from key organisations, and necessary facilities and logistical support (rooms, telephones, administrative support).  Affected and populations at risk need to be alerted if movement/dispersal of the chemical is expected, and advice given about protection measures (e.g. stay indoors, shut windows, don't drink water) or to evacuate vulnerable populations if circumstances demand. 

Other alerts may also be needed, e.g. to food manufacturers that use water from sources at risk of contamination.  Immediate protection and mitigation measures may include evacuation, decontamination of exposed persons, treatment of the injured.  Measures may be needed to try to protect (where possible) vulnerable facilities or environments, such as rivers, aquifers, agricultural land.

The first 24 hours

After the initial phase of response, and within the first 24 hours, the main tasks are to confirm and improve information about the chemicals, their movement in the environment, population exposures, health risks, and to ensure effective liaison between agencies.  Good communication with the public and the media may be important.  Consideration may be given to establishing a telephone helpline and holding a public meeting.  It may be necessary to enlist the input of additional experts and agencies.  It is also the phase in which routine environmental data may be gathered and assessed for evidence about movement of the chemicals and levels of contamination, and additional environmental sampling may be initiated (e.g. of rivers, water courses) in consultation with appropriate laboratories.  Advice to the public and other relevant recipients should be reviewed, and checks made to ensure vulnerable environments are being protected as far as possible, and that actions are being taken to remove and dispose of the contaminants.  Consideration should be given to carrying out biological monitoring of exposed people to determine level of exposure and health effects/risks.

Later steps

In the remainder of the (post-acute) management period, steps are needed to ensure all actions have been carried through appropriately, including the identification and management of exposed persons, the monitoring and management of the contaminants in the environment, and that methods are in place, as appropriate, for gathering, analysing and interpreting needed environmental samples and biological specimens.  Further press releases and follow-up information may be necessary about how the incident is being managed.  In some incidents it may be appropriate to consider a health survey of the local population.  Checks should also be made to ensure that property has been adequately decontaminated, and that evidence-based decisions are made as soon as possible about the safety of drinking water and the like.  Once the incident is considered over, the public should be informed.

Post incident

There may still be need for further measures after the immediate incident has been resolved.  Such measures may include:

- an epidemiological study using routine monitoring data or specific surveys, or by tagging patients notes to identify future health problems
- establishing health checks on the exposed/treated population
- ensuring that remediation of the contaminated site is complete, or if full remediation is not possible, that steps are taken to re-settle the population if the health risks are appreciable  It is also important to ensure that steps are taken to minimise the risk of a similar incident occurring again, and that lessons are learned to improve the management of similar incidents in future.

Water-related incidents




Incidents involving water contamination present special risks, and should involve liaison with water companies (for public water supplies), Environmental Health Practitioners (for private wells/springs), and the Environment Agency[5] for incidents affecting surface waters, aquifers, or marine and coastal waters. If the drinking water supply is contaminated or at risk of contamination, the Drinking Water Inspectorate (DWI)[6] needs to be advised and actions would be needed to alert the public not to drink tap water or to boil it.  Alternative sources may be needed (e.g. bowers, bottled water distributions).  It may also be necessary to stop abstractions from water sources, and to put in place appropriate
monitoring.  Interruptions of water treatment facilities may have adverse effects on water quality. Floods may affect water supplies and pumping stations.




Key references

  • Irwin DJ, Crombie DT, Murray V. Chemical incident management for public health physicians. London: The Stationery Office. 1999. ISBN: 0 11 322107 X.
  • Goodfellow F, Eagles E, Welch F, Murray V.  The environment and public health.  London: The Stationery Office.  2004. ISBN 0 11 322590 3


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                                    © Dr Paul Wilkinson 2009, Helen Crabbe and Rebecca Close 2016