DSEAR – A quick guide


This information is aimed at small to medium sized businesses and those who are self employed. It provides the basic requirements of the Dangerous Substances and Explosive Atmospheres Regulations 2002. It is not comprehensive, it merely provides the headlines. Should you have read this information and still wish to know more please visit the HSE’s Website.

What is DSEAR?

DSEAR is a regulatory requirement which focuses on the protection of the employed and self employed against the risk of fire, explosions and similar energy releasing events which arise from dangerous substances that are either used or are present within a workplace.

What is termed as a Dangerous Substance?

The regulations provide a detailed description of Dangerous Substances, and therefore you should refer to them for more detail. However, in short a Dangerous Substance is any substance or preparation (a combination of substances) which because of its properties or the way it is used could cause harm to people – resulting in fire or explosion. Dangerous substances include petrol, paints, varnishes, and dusts and vapours which when mixed with air could cause an explosive atmosphere. An example of this could be the vapour that comes from petroleum during transfer from one container to another or dusts from sanding operations.

What is an explosive atmosphere?

An explosive atmosphere is when a gas, mist, dust or a vapour are mixed with air which then has the potential to catch fire or explode. The explosive atmosphere does not always mean that an explosion will happen. However if it caught fire the flames would move rapidly and if that took place in a confined space for example this may cause an explosion.

Where does DSEAR apply?

DSEAR applies to most workplaces where a dangerous substance is or could be present.

What is deemed as a workplace under DSEAR?

Under the DSEAR regulations term workplaces are “any premises or parts of premises used for work.”

This includes:-

  • Industrial and commercial premises
  • land-based and offshore installations
  • mines and quarries
  • Construction sites
  • Vehicles and vessels
  • Areas such as the common parts of shared buildings
  • Private roads and paths on industrial estates and road works on public roads
  • Houses and other domestic premises are also deemed as premises if people are at work there.

What are the main requirements of the DSEAR Regulations for employers and the self employed?

DSEAR states that you must:-

  • Carry out risk assessments of any work activities which involve dangerous substances
  • Implement measures to eliminate/ reduce risks as far as is practicable
  • Provide information and train employees in the potential risks and use of equipment.
  • Classify areas where explosive atmospheres may occur into zones and mark these zones clearly.

What is a Risk Assessment?

A risk assessment is systematic means of identifying the dangerous substances that are present or liable to be present in the workplace and the work activities involving them.

The risk assessment looks at how the substances or activities involving the substances could cause a fire or explosion and or similar events (thermal runaway for example) that could harm employees and the public.

The main purpose of the risk assessment is to identify what you need to do to eliminate or reduce the risk, taking into account, the hazardous properties of the substances, the way in which they are used and stored, the possibility of explosion and any potential ignition sources.

Regardless of the quantity of dangerous substances you must carry out a risk assessment which will help you decide whether the current measures you have in place are adequate or whether any additional measures are required.

In addition to routine activities, you must also look at non routine activities such as maintenance which can create a higher probability for fire and explosion incidents to take place.

Does the risk assessment have to be recorded?

If you have five or more employees you must record the significant findings of the assessment as soon as is practicable. This record must include:-

  • The measures that you have taken to eliminate or reduce the risk
  • You must demonstrate that your workplace and equipment will be safe from risk of fire and explosion during normal operation and during maintenance work.
  • You must record the details of any areas that you have zoned as hazardous, (due to the likelihood of an explosive atmosphere)
  • If you as an employer share a workplace, you must record the coordination of your safety requirements such as any special measures to ensure the joint protection of your workers.

What safety measures do the DSEAR Regulations Require?

Under the DSEAR Regulations, you are required to eliminate and or where practicable take measures to control and reduce the safety risks to reduce the potential harmful effects of fire, explosion or similar event.

You might want to think about….

  • Substitution – replace dangerous substances with a substance or process that eliminates the risk – often this is quite hard to achieve. It might be easier to replace the dangerous substance with one that is less hazardous. For example replacing a low-flashpoint solvent with one which has a higher flashpoint.
  • Amending the process. By changing the way the process works you could reduce the risk, for example amending the sequence in which the hazardous substance is added. It is important if you are to review the process that you are mindful of the amends and that one change could present another hazard or health risk, which could potentially counteract the improvement as a result of DSEAR.

Where risk cannot be eliminated, for example the handling or storage of fuel – there needs to be a number of controls put into place to reduce the risks.

Controls to reduce the risk

Controls will reduce the risks involved, and will more than likely include:-

  • reducing the quantity of dangerous substances to a minimum
  • avoiding / minimising releases
  • controlling the release at source
  • prevention of the formation of an explosive atmosphere
  • collect/ contain and remove any releases to a safe place for example through ventilation
  • avoid/ ensure you cover ignition sources
  • avoid extremes in condition – for example exceeding the limits of temperature
  • Ensure that you keep incompatible substances/ preparations apart.

Mitigation to reduce the threat

To further reduce the risk you could:-

  • Re-arrange buildings/ work activities to prevent fires/ explosions spreading from one source of plant and equipment to others
  • Reduce the number of employees that are exposed to the hazardous substance/ activity to a minimum.
  • When dealing with processing plants and equipment, ensure that there is sufficient ventilation and the ability to contain an explosion.
  • When installing new plant or embarking on construction work, measures should be taken to eliminate the risks which should include the installation of control and protection systems.

Are there any further requirements that I need to be aware of where explosive atmospheres can occur?


You must ensure that you classify these areas deemed as potential explosive atmospheres into zones.

Areas which are classified into zones are protected from sources of ignition by selecting equipment and protective systems that meet the “Equipment and Protective Systems Intended for Use in Potentially Explosive Atmospheres Regulations 1996.” However equipment already in use prior to July 2003 can continue to be used so long as there is an up-to-date risk assessment that shows it is safe.

Areas which are classified into zones require an “EX” sign added at their points of entry.

Employees that do work in zoned areas must be provided with the appropriate Personal Protective Equipment (PPE) ensuring that the PPE is appropriate for use for example being anti-static and therefore removing the risk of igniting a potentially explosive atmosphere.

Ahead of the zoned area coming into operation for the first time, they must be verified as safe by an individual or organisation that is competent to do so.

What does DSEAR stipulate when it comes to dealing with accidents, incidents and emergencies?

DSEAR builds on existing requirements under the Management of Health and Safety at Work Regulations 1999; you will need to supplement those existing arrangements if you believe that an accident/ incident/ emergency could arise because of the presence of a dangerous substance at your workplace.

If this is the case, you must ensure that:-

  • Both visual and audible warning alarms are in place
  • Escape facilities are present, should the risk assessment identify this
  • Emergency procedures are in place and fully communicated for use in the event of an incident
  • Suitable PPE is available
  • Practice drills are regularly undertaken to ensure preparedness.

The above measures must be proportionate and aligned to the risk assessment.

Also aligned to the risk assessment you must make the emergency services aware of procedures if necessary.

Information that you must provide to employees and others at the workplace

You must provide your employees and any others at the workplace who may be at risk with suitable information, instructions and training on the precautions required to safeguard themselves and others.

This information should include:-

  • The name of substances used and the risks that they present
  • Access to relevant data sheets
  • Details of the legislation that relates to the substances
  • Any significant findings of the risk assessment.

You may need to provide this information to non-employees when their safety is at risk – but it must be proportionate and aligned to the risk assessment.

Who enforces DSEAR?

DSEAR is enforced by the Health and Safety Executive and/or the local authorities depending on the allocation the premises under the Health and Safety (Enforcing Authority) Regulations 1998. HSE will enforce at industrial premises and local authorities (environmental health officers) elsewhere, for example retail premises.

Fire authorities will also enforce in relation to general fire precautions such as having a means of escape.

If you wish to know more about your obligations as an employer contact PM PROjEN on +44 1928 752 500 where one of their experts will be happy to help.

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