DSEAR Regulations 2002 Overview

This page provides a simple overview of the DSEAR Regulations and explains how they apply in practice. It outlines when DSEAR assessments are required, what substances and activities fall within scope, and the key responsibilities placed on dutyholders. There are 17 regulations in total, you should visit the relevant UK Government legislation webpage for the full detaile list.

The Dangerous Substances and Explosive Atmospheres Regulations 2002 (DSEAR) require employers and dutyholders to assess and control risks from dangerous substances that could cause fire, explosion, or similar hazardous events. Dangerous substances include flammable liquids, gases, vapours, dusts, and oxidising materials that are used, stored, or produced as part of work activities.

Under DSEAR, organisations must identify where explosive atmospheres may occur, classify hazardous zones where necessary, eliminate or reduce ignition sources, and implement appropriate control and mitigation measures. The regulations also require suitable equipment, maintenance regimes, training, and emergency arrangements to be in place.

Regulations, Description and Application Examples

Regulation 1 – Citation and Commencement

This regulation establishes the Dangerous Substances and Explosive Atmospheres Regulations 2002 (DSEAR) as the applicable legal framework governing the control of fire and explosion risks arising from dangerous substances in the workplace.

Example: At your site, the management and control of hydrogen used for testing activities are considered in accordance with the requirements of DSEAR 2002.

Regulation 2 – Interpretation

This regulation defines key terms used throughout DSEAR, including dangerous substance, explosive atmosphere, and workplace, providing the basis for determining whether the regulations apply.

Example: Hydrogen is defined as a dangerous substance, and a release could result in an explosive atmosphere within test or process areas.

Hydrogen is classified as a dangerous substance under DSEAR because it is a highly flammable gas with a very wide flammable range in air and a low ignition energy.

A release of hydrogen can rapidly disperse and, in enclosed or poorly ventilated areas, may accumulate to form an explosive atmosphere if an ignition source is present.

Regulation 3 – Application

This regulation sets out when and where DSEAR applies, including work activities involving the use, storage, handling, or generation of dangerous substances.

Example: The supply of hydrogen via fixed pipework for testing equipment within designated process areas constitutes a work activity to which DSEAR applies, as it involves the intentional use of a flammable gas as part of the work process.

Regulation 4 – Duties under These Regulations

This regulation places general duties on the employer or dutyholder to manage and control risks arising from dangerous substances.

Example: The employer ensures that hydrogen testing activities are properly assessed, controlled, and managed in line with DSEAR requirements, including the implementation of suitable engineering, procedural, and management controls.

Regulation 5 – Risk Assessment

This regulation requires a suitable and sufficient assessment of the risks arising from dangerous substances.

Example: A DSEAR assessment considers foreseeable hydrogen leak points such as regulators, joints, valves, flexible connections, and test interfaces. The assessment evaluates the likelihood and consequences of a release, determines appropriate risk control measures, and considers the need for hazardous area classification and the extent of any classified zones.

Regulation 6 – Elimination or Reduction of Risks from Dangerous Substances

This regulation requires risks to be eliminated or reduced so far as is reasonably practicable, prioritising prevention at source.

Example: Hydrogen inventories are minimised through the use of small-bore pipework, limited test volumes, controlled operating pressures, and the avoidance of unnecessary storage, thereby reducing the potential severity of any release.

Regulation 7 – Places Where Explosive Atmospheres May Occur

This regulation requires the identification and control of places where explosive atmospheres could arise, including the application of hazardous area classification where appropriate.

Example: Localised hazardous area classification is considered at hydrogen test points and connection interfaces where a foreseeable release could occur during normal operation or foreseeable fault conditions.

Regulation 8 – Arrangements to Deal with Accidents, Incidents and Emergencies

This regulation requires appropriate emergency arrangements to be established and maintained.

Example: Emergency isolation valves, gas detection (where required), alarm response procedures, and evacuation arrangements are implemented to manage hydrogen leak or release scenarios, with procedures communicated to relevant personnel.

Regulation 9 – Information, Instruction and Training

This regulation requires employees to receive adequate information, instruction, and training on risks and control measures.

Example: Personnel involved in hydrogen testing activities are trained on hydrogen hazards, system isolation points, safe operating procedures, leak response actions, and emergency arrangements.

Regulation 10 – Identification of Hazardous Contents of Containers and Pipes

This regulation requires clear identification of dangerous substances within containers and pipework.

Example: Hydrogen pipework is clearly labelled to indicate contents and flow direction, with isolation valves readily identifiable to support safe operation and emergency response.

Regulation 11 – Duty of Co-ordination

This regulation requires cooperation and coordination where multiple employers, contractors, or dutyholders share the workplace.

Example: Contractors working within process areas are informed of hydrogen pipe routes, isolation arrangements, hazardous areas (where applicable), and relevant control measures to ensure activities are coordinated safely.

For the full legal text and detailed guidance, you should visit the relevant UK Government legislation webpage for the Dangerous Substances and Explosive Atmospheres Regulations 2002 (DSEAR).

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You may not realise that the use, storage, or processing of flammable liquids, gases, vapours, or combustible dusts can legally require a DSEAR risk assessment. If these substances are present in your workplace, the Dangerous Substances and Explosive Atmospheres Regulations (DSEAR) place duties on employers to assess the risks of fire and explosion and to implement suitable control measures.

At Hielaman, we can help you understand whether DSEAR applies to your activities and carry out a compliant, proportionate DSEAR risk assessment. If you use, store, or process flammable liquids, gases, vapours, or dusts, get in touch to discuss your requirements and ensure your workplace meets its legal duties.

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DSEAR Regulations 2002 Overview

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Regulations, Description and Application Examples

​

Regulation 1 – Citation and Commencement

​

This regulation establishes the Dangerous Substances and Explosive Atmospheres Regulations 2002 (DSEAR) as the applicable legal framework governing the control of fire and explosion risks arising from dangerous substances in the workplace.

​

Example: At your site, the management and control of hydrogen used for testing activities are considered in accordance with the requirements of DSEAR 2002.

​

Regulation 2 – Interpretation

​

This regulation defines key terms used throughout DSEAR, including dangerous substance, explosive atmosphere, and workplace, providing the basis for determining whether the regulations apply.

Example: Hydrogen is defined as a dangerous substance, and a release could result in an explosive atmosphere within test or process areas.

​

Hydrogen is classified as a dangerous substance under DSEAR because it is a highly flammable gas with a very wide flammable range in air and a low ignition energy.

A release of hydrogen can rapidly disperse and, in enclosed or poorly ventilated areas, may accumulate to form an explosive atmosphere if an ignition source is present.

​

Regulation 3 – Application

​

This regulation sets out when and where DSEAR applies, including work activities involving the use, storage, handling, or generation of dangerous substances.

​

Example: The supply of hydrogen via fixed pipework for testing equipment within designated process areas constitutes a work activity to which DSEAR applies, as it involves the intentional use of a flammable gas as part of the work process.

​

Regulation 4 – Duties under These Regulations

​

This regulation places general duties on the employer or dutyholder to manage and control risks arising from dangerous substances.

Example: The employer ensures that hydrogen testing activities are properly assessed, controlled, and managed in line with DSEAR requirements, including the implementation of suitable engineering, procedural, and management controls.

​

Regulation 5 – Risk Assessment

This regulation requires a suitable and sufficient assessment of the risks arising from dangerous substances.

​

Regulation 6 – Elimination or Reduction of Risks from Dangerous Substances

​

This regulation requires risks to be eliminated or reduced so far as is reasonably practicable, prioritising prevention at source.

​

Example: Hydrogen inventories are minimised through the use of small-bore pipework, limited test volumes, controlled operating pressures, and the avoidance of unnecessary storage, thereby reducing the potential severity of any release.

​

Regulation 7 – Places Where Explosive Atmospheres May Occur

​

This regulation requires the identification and control of places where explosive atmospheres could arise, including the application of hazardous area classification where appropriate.

Example: Localised hazardous area classification is considered at hydrogen test points and connection interfaces where a foreseeable release could occur during normal operation or foreseeable fault conditions.

​

Regulation 8 – Arrangements to Deal with Accidents, Incidents and Emergencies

​

This regulation requires appropriate emergency arrangements to be established and maintained.

Example: Emergency isolation valves, gas detection (where required), alarm response procedures, and evacuation arrangements are implemented to manage hydrogen leak or release scenarios, with procedures communicated to relevant personnel.

​

Regulation 9 – Information, Instruction and Training

​

This regulation requires employees to receive adequate information, instruction, and training on risks and control measures.

Example: Personnel involved in hydrogen testing activities are trained on hydrogen hazards, system isolation points, safe operating procedures, leak response actions, and emergency arrangements.

Regulation 10 – Identification of Hazardous Contents of Containers and Pipes

​

This regulation requires clear identification of dangerous substances within containers and pipework.

​

Example: Hydrogen pipework is clearly labelled to indicate contents and flow direction, with isolation valves readily identifiable to support safe operation and emergency response.

​

Regulation 11 – Duty of Co-ordination

This regulation requires cooperation and coordination where multiple employers, contractors, or dutyholders share the workplace.

​

Example: Contractors working within process areas are informed of hydrogen pipe routes, isolation arrangements, hazardous areas (where applicable), and relevant control measures to ensure activities are coordinated safely.

​

For the full legal text and detailed guidance, you should visit the relevant UK Government legislation webpage for the Dangerous Substances and Explosive Atmospheres Regulations 2002 (DSEAR).

​

Get in touch

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