The Dangerous Substances and Explosive Atmospheres Regulations 2002 (DSEAR) require employers in Great Britain to assess and control safety risks from dangerous substances, including fire, explosion and corrosion of metal. Where dangerous substances are stored, employers must identify the hazards, eliminate or reduce risks so far as reasonably practicable, control ignition sources and prepare suitable emergency arrangements.
DSEAR stands for the Dangerous Substances and Explosive Atmospheres Regulations 2002.
The Regulations are the principal Great Britain workplace requirements for controlling safety risks arising from dangerous substances capable of causing fire, explosion, similar energetic events or corrosion of metal.
DSEAR applies in England, Scotland and Wales. Northern Ireland has separate Dangerous Substances and Explosive Atmospheres Regulations.
DSEAR places duties on employers and the self-employed to protect employees and other people who may be put at risk by dangerous substances associated with work activities.
Yes. HSE guidance states that DSEAR applies to workplaces that manufacture, store, process or use dangerous substances.
Storage should therefore be considered as part of the DSEAR risk assessment where the substances present could create relevant safety risks.
The assessment may need to consider:
DSEAR covers substances or mixtures that could create a risk to people’s safety through fire, explosion, similar energetic events or corrosion of metal.
Examples can include:
Dangerous substances can be brought into the workplace or generated by a work process.
Employers must identify dangerous substances and assess the risks they create before deciding what controls are required.
The main DSEAR duties include:
Regulation 5 requires employers to make a suitable and sufficient assessment of the risks to employees arising from dangerous substances present or liable to be present at the workplace.
Factors to consider include:
The assessment should reflect the actual workplace and activities rather than relying solely on generic information about the substance.
DSEAR requires employers to eliminate risks from dangerous substances so far as is reasonably practicable.
Where elimination is not reasonably practicable, risks must be reduced so far as reasonably practicable using appropriate technical and organisational measures.
This can include:
Flammable liquid storage should be arranged so that the likelihood and consequences of fire or explosion are reduced as far as reasonably practicable.
Important considerations can include:
HSE guidance states that containers of flammable liquids needed for current work activities should normally be kept closed when not in use and stored in suitable fire-resisting cabinets or bins designed to retain spills.
DSEAR does not establish one absolute quantity limit that applies to every workplace. The employer must justify the quantity kept within a workroom through the DSEAR risk assessment.
HSE guidance recommends keeping only the minimum quantity needed for frequently occurring activities or approximately one shift’s requirements within the work area.
HSE identifies recommended maxima of:
HSE describes these figures as recommended maxima representing good industry practice rather than absolute legal limits. Where larger quantities are required, the employer should be able to justify them through a robust risk assessment.
For suitable flammable liquid cabinets or bins used in workrooms, HSE guidance recommends spill retention equivalent to at least 110% of the volume of the largest vessel normally stored within the cabinet or bin.
This recommendation is specific to the workroom storage arrangements described by HSE and should not be treated as a universal DSEAR bunding requirement for every chemical storage installation.
Larger stores, outdoor installations and environmentally regulated sites may require different containment arrangements based on their individual risks and other applicable requirements.
Where an explosive atmosphere may occur in quantities requiring special precautions, the employer must identify and classify the relevant parts of the workplace into hazardous zones.
The classification depends on how likely an explosive atmosphere is to occur and how long it is likely to persist.
The zoning system differs for gases, vapours and mists compared with combustible dusts.
The size and extent of any zone should be established from the release sources, substance properties, ventilation and operating conditions involved.
No. The presence of a flammable substance does not automatically mean that the entire room or storage area must be classified as a hazardous zone.
The assessment must determine whether an explosive atmosphere could occur, where it could occur, how frequently it may arise and how long it could persist.
Container integrity, ventilation, transfer operations, dispensing, charging and foreseeable releases can all affect the classification.
Where a flammable atmosphere could occur, employers should identify and control sources capable of causing ignition.
Potential ignition sources include:
Equipment installed within a classified hazardous area must be suitable for the zone and explosive atmosphere involved.
DSEAR requires suitable equipment to be selected for areas classified as hazardous because of potentially explosive atmospheres.
In Great Britain, equipment and protective systems intended for use in explosive atmospheres are covered by the Equipment and Protective Systems Intended for Use in Potentially Explosive Atmospheres Regulations 2016.
The term “ATEX” is still commonly used when discussing explosive-atmosphere equipment, but the workplace duties under DSEAR and the product requirements applying to equipment are separate legal requirements.
Equipment selection should be based on the hazardous-area classification, substance characteristics and relevant equipment category or protection level.
Where required, entry points to areas classified as hazardous because of potentially explosive atmospheres must be identified using the specified explosion-hazard warning sign.
The familiar yellow and black EX sign is used to identify relevant areas where special precautions are required.
The need for signage should follow from the hazardous-area classification and the requirements of DSEAR.
Yes. Before a workplace containing newly classified hazardous areas is used for the first time, the overall explosion safety measures must be verified as being safe.
The verification should be carried out by a person or organisation competent to consider the explosion risks and the adequacy of the prevention and protection measures in place.
Relevant documentation may include hazardous-area classifications, equipment specifications, risk assessments and evidence that the required controls have been installed correctly.
Where the risk assessment identifies a foreseeable accident, incident or emergency involving dangerous substances, employers must make suitable arrangements to protect people who could be affected.
Depending on the workplace, this can include:
Emergency arrangements should reflect credible incidents identified through the DSEAR risk assessment.
Employees who may be affected by dangerous substances must receive appropriate information, instruction and training.
This should cover matters such as:
The level of training should be proportionate to the risks and the employee’s role.
DSEAR and COSHH can both apply to the same chemical, but they control different types of risk.
For example, a flammable solvent may create a health risk from inhalation under COSHH and a fire or explosion risk under DSEAR.
The two assessments should therefore complement each other rather than one being used as a substitute for the other.
See our COSHH Regulations guide for further information.
DSEAR applies broadly to workplace safety risks involving dangerous substances, while COMAH applies only to establishments where specified dangerous substances are present at or above defined qualifying quantities.
A facility can therefore be subject to DSEAR without being a COMAH establishment.
Where COMAH does apply, DSEAR duties may still be relevant alongside the wider major-accident prevention requirements.
The Dangerous Substances and Explosive Atmospheres Regulations 2002 discussed on this page apply in Great Britain.
Northern Ireland has separate legislation: the Dangerous Substances and Explosive Atmospheres Regulations (Northern Ireland) 2003.
Businesses operating in Northern Ireland should refer to the Health and Safety Executive for Northern Ireland and confirm the requirements applying to their site.
Chemstore provides hazardous material storage solutions that can form part of the control measures identified through a site’s DSEAR and wider workplace risk assessments.
For flammable liquids, the Firevault range provides fire-rated hazardous material storage for applications involving larger quantities or dedicated storage requirements.
For smaller indoor quantities, Chemstore also supplies fire-rated and hazardous material safety cabinets.
The appropriate storage solution should be selected from the substances, quantities, fire and explosion risks, ventilation requirements and findings of the site-specific risk assessment.
No individual storage product makes a workplace automatically compliant with DSEAR.
The Health and Safety Executive and UK legislation website provide the primary sources for DSEAR requirements in Great Britain.
This page provides general information about the Dangerous Substances and Explosive Atmospheres Regulations 2002 and hazardous material storage in Great Britain. It does not replace the Regulations, HSE guidance, a DSEAR risk assessment, hazardous-area classification or advice from a competent person.
The measures required for an individual workplace should always be determined from the dangerous substances, quantities, processes, possible releases, ignition sources and site-specific risks involved.
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