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The Dangerous Substances and Explosive Atmospheres Regulations’ (DSEAR)

DSEAR is an acronym used regularly in the world of health and safety to describe a huge business risk – but what does it even mean? How are you meant to know if it applies to your business? DSEAR stands for ‘The Dangerous Substances and Explosive Atmospheres Regulations’ and applies whenever there is work being carried out, a dangerous substance is present and the dangerous substance could be a risk to the safety of people as a result of fires or explosions.

The following are examples of activities covered by DSEAR:

  • storage of petrol as a fuel
  • use of flammable gases, such as acetylene, for welding
  • handling and storage of waste dusts
  • handling and storage of 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
  • storage and display of flammable goods, such as paints
  • filling, storing and handling aerosols with flammable propellants such as LPG
  • transporting flammable substances in containers around a workplace
  • handling, storage and use of gases under pressure
  • handling, storage and use of substances corrosive to metal.

If your business carries out any of the activities above you must act now!

Risk assessment – Before work is carried out, the risks involved in the use of dangerous substances must be assessed. Control measures must then be put in place to eliminate risks or reduce them as far as is reasonably practicable.


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
  • control releases of dangerous substances at source
  • prevent the formation of a dangerous atmosphere
  • 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


In addition to control measures, DSEAR requires employers to put mitigation measures in place:

  • reducing the number of employees exposed to the risk
  • providing plant that is explosion resistant
  • providing plant that is corrosion 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


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.

Training – Employees must be provided with relevant information, instructions and training. This includes the dangerous substances present in the workplace and the risks they present; the findings of the risk assessment and the control measures put in place as a result and emergency procedures.


It is a daunting topic and it may all sound a little over the top for your business but is it? A company that thought just that has recently received a large fine for overlooking such a scenario. A fire started during a chemical dispensing operation in a warehouse. A flammable vapour created during the process came into contact with an ignition source causing the vapour to ignite.

In this case, the operator dropped the can, exited the warehouse and raised the alarm meaning that no one was injured. The fire spread quickly however and destroyed the warehouse. The company was fined £14,000 and ordered to pay £2,377 in costs.

It really highlights the importance of assessing risks associated with flammable atmospheres. Are you confident you have the use of dangerous substances and the risk of fire and explosion in your premises under control?

If we can be of assistance with any health and safety management topic, please get in touch on 01302 341 344.

By Rachel Cuff CMIOSHRisk Consultant

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