SC20 - Appendix 1
06 Dec 2010



Requirements of DSEAR




This A​ppendix gives background information on DSEAR, explaining what is needed from the employer / user to comply with the regulations. More detailed guidance on specific areas, including hazardous area classification and selection of equipment is available in Appendix 2, and should be suitable to ensure DSEAR compliance in 80% of cases on the STFC sites. Note that any risk assessment under the DSEAR legislation should complement other risk assessments for example asset protection, COSHH etc.

DSEAR require employers to:

  • find out what dangerous substances are in their workplace and what the fire and explosion risks are;
  • put control measures in place to either remove those risks or, where this is not possible, control them;
  • put controls in place to reduce the effects of any incidents involving dangerous substances;
  • prepare plans and procedures to deal with accidents, incidents and emergencies involving dangerous substances;
  • make sure employees are properly informed about and trained to control or deal with the risks from the dangerous substances;
  • identify and classify areas of the workplace where explosive atmospheres may occur and avoid ignition sources (from unprotected equipment, for example) in those areas.
A1.1 What is the relationship between ATEX, DSEAR and EPS?

ATEX is the name commonly given to the framework for controlling explosive atmospheres and the standards of equipment and protective systems used in them. It is based on the requirements of two European Directives.

  • Directive 99/92/EC (also known as 'ATEX 137' or the 'ATEX Workplace Directive') is a social directive and defines the minimum requirements for improving the health and safety protection of workers potentially at risk from explosive atmospheres.

  • Directive 94/9/EC (also known as 'ATEX 95' or 'the ATEX Equipment Directive') on the approximation of the laws of Members States concerning equipment and protective systems intended for use in potentially explosive atmospheres. The aim of this Directive is to allow the free trade of 'ATEX' equipment and protective systems within the EU by removing the need for separate testing and documentation for each Member State.

In Great Britain the requirements of Directive 99/92/EC were put into effect through regulations 7 and 11 of the Dangerous Substances and Explosive Atmospheres Regulations 2002 (DSEAR). DSEAR also incorporates parts of the old Chemical Agents Directive, in particular to assess risks associated with substances that could give rise to dangerous chemical reactions as well as those substances that may form flammable atmospheres as defined in ATEX. Expansion of DSEAR in 2015 also requires consideration of gases under pressure and corrosive chemicals.

The requirements of Directive 94/9/EC were put into effect through the DTI's Equipment and Protective Systems for Use in Potentially Explosive Atmospheres Regulations 1999 (as amended) (EPS Regulations). The Regulations apply to all equipment intended for use in explosive atmospheres, whether electrical or mechanical, and also to protective systems.

Manufacturers/suppliers (or importers, if the manufacturers are outside the EU) must ensure that their products meet essential health and safety requirements and undergo appropriate conformity procedures. This usually involves testing and certification by a 'third-party' certification body (known as a Notified Body) but manufacturers/suppliers can 'self-certify' equipment intended to be used in less hazardous explosive atmospheres. Once certified, the equipment is marked by the 'EX' symbol to identify it as such.

Certification ensures that the equipment or protective system is fit for its intended purpose and that adequate information is supplied with it to ensure that it can be used safely.

A1.2 When and where does DSEAR apply?

Apart from certain activities involving ships, DSEAR applies whenever:

  • there is work being carried out by an employer (or self-employed person);
  • a dangerous substance is present (or is liable to be present) at the workplace;
  • the dangerous substance could be a risk to the safety of people as a result of fires, explosions or similar energetic events.

Fires and explosions create harmful physical effects - thermal radiation, overpressure effects and oxygen depletion. These effects can also be caused by other energetic events such as runaway exothermic reactions involving chemicals or decomposition of unstable substances such as peroxides. These events are also covered by DSEAR.

The following examples illustrate the type of activities covered by DSEAR:

  • use of flammable gases, such as acetylene for welding;
  • handling and storage of waste dusts in a range of manufacturing industries;
  • handling and storage of flammables and flammable wastes such as fuel oils;
  • welding or other 'hot work' on tanks and drums that have contained flammable material;
  • work that could release naturally occurring flammable substances such as methane in coalmines or at landfill sites;
  • use of flammable solvents in laboratories;
  • filling, storing and handling aerosols with flammable propellants such as LPG;
  • transporting flammable substances in containers around a workplace;
  • deliveries from road tankers, such as petrol and bulk powders;
  • chemical manufacturing, processing and warehousing;
  • the petrochemical industry, both onshore and offshore;
  • loss of containment resulting in undesirable reaction e.g. sodium hydroxide reacting with aluminium to liberate hydrogen.

DSEAR applies to workplaces where dangerous substances are present, used, or produced. Workplaces are any premises or parts of premises used for work. This includes places such as industrial and commercial premises, land-based and offshore installations, mines and quarries, construction sites, vehicles and vessels, etc. Places such as the common parts of shared buildings, private roads and paths on industrial estates and road works on public roads are also premises – as are houses and other domestic premises, if people are at work there.

A1.3 What are dangerous substances?

Dangerous substances are substances or mixtures of substances (called 'preparations' in DSEAR) that could create risks to people's safety from fires and explosions or similar events, such as 'thermal runaway' from chemical reactions. Liquids, gases, vapours and dusts that may be found in a workplace can all be dangerous substances.

Dangerous substances include:
  • substances or mixtures of substances classified as explosive, oxidising, extremely flammable, highly flammable, or flammable under the current CLP Regulations.

  • any kind of dust that when spread in air to form a cloud (i.e. form an explosive atmosphere), can explode. ​

  • any other substances, or mixtures of substances, which because of their physical properties and the way in which they are present in the workplace create a risk to safety from fires and explosions, but which may not be covered by CLP. For example high flashpoint liquids present in the workplace at elevated temperatures.

Many of these substances can also create health risks, for example, they may be toxic or an irritant. These kinds of risks are covered under separate legislation such as the Control of Substances Hazardous to Health Regulations (COSHH). It is important to consider both safety and health issues when looking at risks from substances in the workplace.

A1.4 How do I comply with DSEAR?

DSEAR places duties on employers to assess and eliminate or reduce risks from dangerous substances. Complying with DSEAR involves:

Assessing risks

Before work is carried out, the fire and explosion risks that may be caused by dangerous substances must be assessed. This should be an identification and careful examination of:

  • the dangerous substances in the workplace;
  • the work activities involving those substances; and
  • the ways in which those substances and work activities could harm people.

The purpose is to help employers to decide what they need to do to eliminate or reduce the risks from dangerous substances.

If there is no risk to safety from fires and explosions, or the risk is trivial, no further action is needed. If there are risks then employers must consider what else needs to be done to comply fully with the requirements of DSEAR. If an employer has five or more employees, the employer must record the significant findings of the risk assessment.

Preventing or controlling risks

Control measures must be put in place to eliminate risks from dangerous substances, or reduce them as far as is reasonably practicable. Where it is not possible to eliminate the risk completely measures must be taken to control risks and reduce the severity (mitigate) the effects of any fire or explosion

The best solution is to eliminate the risk completely by replacing the dangerous substance with another substance, or using a different work process. For example, replacing a low flashpoint liquid with a high flashpoint one.

Control measures

Where the risk cannot be eliminated, DSEAR requires control measures to be applied in the following priority order:

  • reduce the quantity of dangerous substances to a minimum;
  • avoid or minimise releases of dangerous substances e.g. via the use of fully contained systems such as welded pipework;
  • control releases of dangerous substances at source;
  • prevent the formation of a dangerous atmosphere e.g. operating below flashpoint of a dangerous substance;
  • collect, contain and remove any releases to a safe place (for example, through ventilation);
  • avoid ignition sources;
  • avoid adverse conditions (for example, exceeding the limits of temperature or control settings) that could lead to danger;
  • keep incompatible substances apart.

These control measures should be consistent with the risk assessment and appropriate to the nature of the activity or operation.

In addition to control measures DSEAR requires mitigation measures to be put in place. These measures should be consistent with the risk assessment and appropriate to the nature of the activity or operation and include:

  • reducing the number of employees exposed to the risk;
  • providing plant that is explosion resistant;
  • providing explosion suppression or explosion relief equipment;
  • taking measures to control or minimise the spread of fires or explosions;
  • providing suitable personal protective equipment.
​Preparing emergency plans and procedures

Arrangements must be made to deal with emergencies. These plans and procedures should cover safety drills and suitable communication and warning systems and should be in proportion to the risks. If an emergency occurs, workers tasked with carrying out repairs or other necessary work must be provided with the appropriate equipment to allow them to carry out this work safely.

The information in the emergency plans and procedures must be made available to the emergency services to allow them to develop their own plans if necessary. Providing information, instruction and training for employees

Employees must be provided with relevant information, instructions and training. This includes:

  • the dangerous substances present in the workplace and the risks they present including access to any relevant safety data sheets and information on any other legislation that applies to the dangerous substance;
  • the findings of the risk assessment and the control measures put in place as a result (including their purpose and how to follow and use them);
  • emergency procedures.

Information, instruction and training need only be provided to other people (non-employees) where it is required to ensure their safety. It should be in proportion to the level and type of risk.

The contents of pipes, containers, etc must be identifiable to alert employees and others to the presence of dangerous substances. If the contents have already been identified in order to meet the requirements of other law, this does not need to be done again under DSEAR. For example natural gas systems for domestic purposes such as the provision of heating and hot water in offices or canteens need not be considered under DSEAR since these are covered under the relevant (and more prescriptive) gas installation codes.

Places where explosive atmospheres may occur ('ATEX' requirements)

DSEAR places additional duties on employers where potentially explosive atmospheres may occur in the workplace. These duties include:

  • identifying and classifying (zoning) areas where potentially explosive atmospheres may occur (refer to Hazardous Area Classification Section in Appendix 2);

  • controlling ignition sources in zoned areas, in particular those from electrical and mechanical equipment (refer to Selection of Equipment Section in Appendix 2);

  • where necessary, identifying the entrances to zoned areas;

  • providing appropriate anti-static clothing for employees (refer to Control of Ignition Sources section in Appendix 2);

  • before they come into operation, verifying the overall explosion protection safety of areas where explosive atmospheres may occur i.e. ensure that someone competent has reviewed the DSEAR assessment.
Contact: Baker, Gareth (STFC,DL,COO)