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    DSEARDangerous Substances and Explosive Atmospheres Regulations

    Definition

    Dangerous Substances and Explosive Atmospheres Regulations 2002 — controls for fire, explosion and related dangerous-substance risks at work in Great Britain.

    Editorial definition: The QHSE Standard, updated 3 October 2026 · https://qhsetech.com/glossary/dsear

    Scope: This safety framework is distinct from assessing health exposure under COSHH.

    Sources checked: . Examples are editorial illustrations.

    What HSE and the regulations say about DSEAR

    DSEAR means Dangerous Substances and Explosive Atmospheres Regulations 2002, Statutory Instrument 2002 number 2776. HSE says they require employers to control the safety risks from fire, explosions and substances that corrode metals, and place duties on employers and on the self-employed to protect people at work and members of the public put at risk by work activity. HSE describes dangerous substances as substances that are used or present at work and could, unless properly controlled, lead to harm through fire, explosion or metal corrosion, and lists solvents, paints, varnishes, flammable gases such as LPG, dusts from machining, sanding and foodstuffs, pressurised gases and substances that corrode metal. HSE also says DSEAR implements the ATEX workplace directive in Great Britain.

    The text of the regulations sets out the duties. When dangerous substances are or may be present, the employer assesses the risks to employees from it, and the assessment must be suitable and sufficient. It must consider the hazardous properties, the supplier's safety information including any safety data sheet, the circumstances of the work, maintenance activities, how likely an explosive atmosphere is and how long it would last, the likelihood of ignition sources and the scale of the effects. It is reviewed regularly and after significant change, and an employer with five or more employees records its significant findings. Risk is to be eliminated or, failing that, reduced so far as reasonably practicable, with substitution preferred, and control measures are listed in order of priority, from reducing the quantity and minimising or controlling releases to preventing the formation of an explosive atmosphere, avoiding ignition sources and segregating incompatible substances.

    Places where explosive atmospheres may occur are classified into hazardous and non-hazardous places and the hazardous ones into zones 0, 1 and 2 for gas, vapour or mist and zones 20, 21 and 22 for dust, by the frequency and duration of the atmosphere. Equipment is selected by category for each zone, signs are used where necessary, and a competent person verifies overall explosion safety before a workplace is first used. Further duties cover emergency arrangements, information, instruction and training, identifying what hazardous substances containers and pipes hold, and coordination between employers. The summary covers Great Britain only and is general information, not legal advice.

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    What a DSEAR record holds in software

    • A register of dangerous substances giving product, quantity, location and form, tied to each product's latest data sheet.
    • The risk assessment with its date, author, review trigger and significant findings.
    • The classification of places into zones, with the substance, the basis and the drawing revision.
    • The control measures in the order of priority, including whether substitution was considered and why it was or was not practicable.
    • The record of equipment in classified places and its suitability for the zone.
    • Verification of overall explosion safety, with the competent person and the date.
    • Emergency arrangements, drills, training and information given, and the coordination agreed with other employers.

    DSEAR, ATEX, COSHH and the permit system

    DSEAR is the Great Britain regulation, and HSE says it implements the ATEX workplace directive. ATEX also names a separate equipment directive that applies to manufacturers. A DSEAR assessment concerns safety risks from fire, explosion and corrosion of metals, while a permit to work is one control used to carry work out in a classified place and does not replace the assessment. Check which regulation covers a given hazard before assuming one assessment answers every duty.

    A hypothetical example: a joinery workshop

    This invented case describes no real business and shows how the records connect. A workshop applies a solvent-based finish and operates a dust extraction unit. The assessor lists the finish, its thinner and the wood dust in the substance register and links each safety data sheet. For the finishing area the assessment considers the quantity kept in the room, how vapour could escape and how long it would last, and the sources of ignition. The first control chosen is to reduce the stock kept in the room and to ask the supplier about a lower-hazard product.

    The assessor classifies the finishing area and the inside of the extraction unit into zones using the frequency and duration of an explosive atmosphere, and records the basis and the drawing revision. Equipment in those places is checked against the zone. A competent person verifies the arrangement before the new finishing area is first used. When the workshop later changes the finish, the system flags the assessment for review, and the substitution question is answered again with the new product.

    Common misunderstandings about DSEAR

    • DSEAR is not limited to the chemical industry. HSE says dangerous substances are found in nearly all workplaces, and its examples include paints, solvents, LPG and dusts from machining.
    • Having a safety data sheet is not the assessment. The regulations require the data sheet information to be considered within the employer's own assessment of the work.
    • Small employers are not exempt. The duty to assess applies to employers and the self-employed, and the requirement to record significant findings is the part that depends on having five or more employees.
    • Classification of a place into a zone is not a one-off. The assessment is reviewed after significant change, and the zone drawing needs the same attention.
    • A permit or a procedure does not remove the hierarchy. The regulations prefer substitution and then list control measures in order of priority.

    How DSEAR relates to other glossary terms

    DSEAR connects the substance records, the hazardous-area classification and the permit system.

    • ATEX: the two directives on explosive atmospheres, one of which DSEAR implements in Great Britain.
    • SDS: the supplier's safety data sheet is one of the inputs the risk assessment must consider.
    • Permit to work: controls work in classified places, but does not replace the assessment.
    • Hierarchy of controls: a similar order of preference to the priority order the regulations give.

    Records and evidence that usually exist for DSEAR duties

    • The substance register and the current safety data sheets.
    • The risk assessment and its review records.
    • The zone classification with its basis, drawings and revisions.
    • The record of equipment selection for classified places.
    • The verification of overall explosion safety before first use.
    • Emergency arrangements, drill records and training records.

    What a software tool needs to capture for DSEAR

    • A substance register that links each product to its current data sheet and to the places where it is used.
    • Assessment fields that show each of the factors the regulations list, not a single score.
    • A place to record the substitution decision and the order of control measures applied.
    • A zone register linked to drawings with revisions.
    • A review prompt after a change of substance, quantity, process or layout.
    • Links to permits to work, drills and training records, with an export for an inspector.

    Catalog profiles documenting chemical management

    This list follows the chemical management rule and says nothing about zone registers or the assessment factors that DSEAR lists; test those in a demonstration.

    Same rule for every product: tagged “Chemical Management”, with a sourced SDS or chemical inventory capability in its record, or one the vendor stated to us, labelled as vendor-stated. Documented and conditional capabilities qualify; check the linked scope before treating a module as included.

    Tekmon pays for a sponsored placement (above); its place in this list follows the same rule as every entry. How lists are ordered

    All 11 matching profiles are shown. Documentation review, not hands-on testing or a claim of compliance.

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    Frequently asked questions

    Does DSEAR apply to small businesses?

    HSE says it places duties on employers and on the self-employed. Recording the significant findings is required only where there are five or more employees, but the duty to assess applies whatever the size of the business.

    Is DSEAR only about explosions?

    No. HSE describes it as controlling the safety risks from fire, explosions and substances that corrode metals. The regulations define a dangerous substance by hazard, so solvents, flammable gases and some dusts can fall within them.

    Can a dust cloud be an explosive atmosphere?

    Yes. The definition covers mixtures of air with gases, vapours, mists or dusts in which combustion spreads to the entire unburned mixture, and the zone system includes dust zones. Whether a given dust qualifies is a matter for the assessment.

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