Quick answer: DSEAR is the Dangerous Substances and Explosive Atmospheres Regulations 2002 (SI 2002/2776). It puts a duty on every UK employer and self-employed person to find out which substances in the workplace could cause a fire, an explosion or a similar energetic event (and, since 2015, which gases are under pressure and which substances are corrosive to metal), to assess the risk, to remove or reduce it as far as is reasonably practicable, to plan for emergencies, to inform and train staff, and to classify any area where an explosive atmosphere could form. It sits alongside COSHH, which deals with harm to health from the same substances. For most warehouses, workshops and yards the practical end of DSEAR is how flammable liquids, gas cylinders and fuels are stored and how far they are kept from anything that could ignite them — which is where this guide, written by a storage equipment supplier rather than a consultancy, concentrates.
What DSEAR is, and what changed in 2015
The regulations came into force in 2002 and are the primary UK legislation for controlling substances that can cause fires and explosions at work. The HSE describes the scope as risks to safety from fire, explosions and substances corrosive to metals; the original 2002 text covered fire and explosion, and an amendment in 2015 brought gases under pressure and substances corrosive to metal into scope. The reason the amendment matters to a storage buyer is simple: a compressed gas cylinder is now a DSEAR substance in its own right, whether or not its contents are flammable, so an oxygen or nitrogen cylinder store is a DSEAR matter as well as an acetylene or propane one. The full text is on legislation.gov.uk and the HSE's own summary is at hse.gov.uk/fireandexplosion/dsear.htm.
What counts as a dangerous substance
The HSE's list is broader than most people expect. Dangerous substances are any substances used or present at work that could, if not properly controlled, cause harm to people through fire, explosion or corrosion of metal. The HSE's own examples are solvents, paints, varnishes, flammable gases such as LPG, dusts from machining and sanding, dusts from foodstuffs, pressurised gases and substances corrosive to metal. Formally, a dangerous substance is anything that meets the criteria for a physical hazard class under the CLP Regulation (classified or not), any dust that can explode when spread in air as a cloud, and anything else whose physical properties and the way it is present create a fire or explosion risk — for example a high-flashpoint liquid held at elevated temperature.
One consequence of CLP is worth knowing if you store fuel. The upper flashpoint for classification as a flammable liquid was raised to 60 °C, which means diesel, gas oil and light heating oils are now classified as flammable liquids. The HSE's guidance is explicit that many substances classified this way do not normally present a significant fire risk as stored, and that employers should take a proportionate approach rather than assume the reclassification demands new measures. A drum of diesel in a bunded store has not become more dangerous because its label changed; but it is now inside DSEAR's scope and should appear in the assessment.
Who DSEAR applies to
DSEAR applies whenever an employer or self-employed person is carrying out work, a dangerous substance is present or liable to be present, and that substance could put people at risk through fire, explosion, a similar energetic event or corrosion to metal. The workplace definition is wide: industrial and commercial premises, vehicles and vessels, construction sites, the common parts of shared buildings, private roads on industrial estates and even domestic premises if people are at work there. The HSE's list of activities in scope includes storing petrol for machinery, using acetylene for welding, storing flammable wastes such as fuel oils, storing and displaying flammable goods such as paints in shops, handling aerosols with LPG propellants, transporting flammable substances in containers around a workplace, and the handling, storage and use of gases under pressure. A distribution warehouse holding pallets of aerosols or solvent-based products is a DSEAR workplace even though nobody there opens a container. So is a maintenance workshop with a gas welding set and a cabinet of thinners.
The six duties on an employer
The HSE's quick guide reduces DSEAR to six things an employer must do. The table sets them out with what each usually means in a warehouse or workshop.
| DSEAR duty | What it means in practice |
|---|---|
| Find out what dangerous substances are present and what the risks are | An inventory: every flammable liquid, gas cylinder, fuel, oxidiser, combustible dust and corrosive-to-metal substance, where it is, how much, and how it is used. Safety data sheets give the classification. |
| Put control measures in place to remove the risk or, where that is not possible, control it | Substitute a safer product where you can; otherwise reduce quantities, store in suitable cabinets or outdoor stores, control releases and keep ignition sources away. |
| Put controls in place to reduce the effects of any incident | Mitigation: fewer people exposed, fire-resisting storage, sumps and bunds to contain a release, means of limiting the spread of a fire. |
| Prepare plans and procedures for accidents, incidents and emergencies | Proportionate to the risk: drills, warning systems, what to do on a spill or a cylinder leak, information available to the fire service. |
| Inform and train employees | What is present, the findings of the assessment, the controls and why they exist, and the emergency procedures. Containers and pipes must be identifiable. |
| Identify and classify areas where explosive atmospheres may occur and avoid ignition sources in them | Hazardous area classification into zones, and only suitably protected equipment inside those zones. This is the part that overlaps with ATEX. |
If you employ five or more people you must record the significant findings of the assessment. If the assessment shows no risk, or a trivial one, no further action is needed — DSEAR does not require paperwork for its own sake.
The control hierarchy DSEAR actually specifies
Where a risk cannot be eliminated, the regulations require control measures in a stated order of priority. The HSE lists them as: reduce the quantity of dangerous substances to a minimum; avoid or minimise releases; control releases at source; prevent the formation of a dangerous atmosphere; collect, contain and remove any releases to a safe place; avoid ignition sources; avoid adverse conditions such as exceeding temperature limits; and keep incompatible substances apart. Mitigation measures then sit on top: reducing the number of employees exposed, explosion-resistant or corrosion-resistant plant, explosion suppression or relief, measures to control the spread of fire, and suitable PPE.
Read that list as a storage buyer and most of it is about containers, cabinets and where they stand. Reducing quantities means holding only what the workroom needs and keeping the bulk somewhere better protected. Containing releases means sumps and bunds. Keeping incompatible substances apart means separate cabinets for flammables, acids and agrochemicals rather than one cupboard for everything. Avoiding ignition sources is as much about siting — a cylinder cage outdoors and away from the welding bay — as it is about equipment.
Zones and ATEX: the part most storage buyers can keep short
DSEAR requires areas where an explosive atmosphere may occur to be classified into zones according to how often and for how long that atmosphere is likely to be present: Zones 0, 1 and 2 for gases, vapours and mists, and Zones 20, 21 and 22 for combustible dusts, with Zone 0 and Zone 20 being the most severe. Equipment used inside a zone must be suitable for it, which is where the ATEX equipment regulations (in Great Britain, the Equipment and Protective Systems Intended for Use in Potentially Explosive Atmospheres Regulations 2016, with UKCA marking) come in. The HSE's guidance on this is at hse.gov.uk/fireandexplosion/atex.htm.
Two plain statements will save confusion. First, DSEAR is the workplace regulation that tells you to classify areas and control ignition sources; ATEX is the product regulation that governs equipment designed to be used in those areas. They are not alternatives and neither replaces the other. Second, a steel storage cabinet, a cylinder cage or a spill pallet is not ATEX equipment — it has no motor, no switch and no ignition source of its own — and we do not describe any product on this site as ATEX-certified. If your assessment produces a zoned area, the electrical equipment, lighting, fork trucks and tools that go into it are what need the category marking, and that is a specification for your electrical contractor and equipment supplier, not for a cabinet.
DSEAR and COSHH: two regulations, one cabinet
The most common question is how DSEAR differs from COSHH, and the HSE answers it directly: some dangerous substances also create health risks — they may be toxic or irritant — and those risks are covered by separate health law, principally COSHH. DSEAR is about safety (fire, explosion, corrosion of metal); COSHH is about health (exposure, inhalation, skin contact). A drum of solvent is a DSEAR substance because it burns and a COSHH substance because its vapour harms the lungs. The same cabinet frequently serves both, but the specification differs: a COSHH cupboard for a corrosive or toxic liquid needs a sump and segregation, while a cabinet for a flammable liquid also needs fire-resisting construction. Our flammable storage cabinet vs COSHH cabinet guide sets out that distinction in detail, and the COSHH cabinet requirements guide covers the health-side rules, including the practical capacity limits for flammables kept in a workroom.
Who needs a DSEAR assessment, and who can do it
Any employer or self-employed person with a dangerous substance present must assess the risk before work is carried out; that is the duty, and there is no size threshold below which it disappears (the five-employee threshold is for recording the findings, not for doing the assessment). The regulations require the assessment to be suitable and sufficient, and in practice that means it must be done by someone competent for the complexity of the site. For a small workshop with a flammables cabinet, a couple of gas cylinders and no zoned areas, a competent manager working from the safety data sheets and the HSE guidance may well be able to do it. For a site that needs hazardous area classification — bulk solvent storage, a paint mixing room, a flour or wood-dust process, a fuel installation — the zoning work normally needs specialist input. We should be clear about our own position: KC Supply sells storage equipment and does not carry out DSEAR risk assessments, hazardous area classification, explosion protection documents or DSEAR training, and there is a good argument that whoever assesses your site should be independent of whoever sells you the cabinets.
What DSEAR means for how you store things
The table below maps the DSEAR control measures to the storage equipment that usually delivers them. Every specification quoted comes from the product listing; where a product's data does not state something, we say so.
| DSEAR measure | Storage answer | What the product data says |
|---|---|---|
| Reduce the quantity in the workroom; contain releases; limit fire spread | Flammable liquid cabinets | GPC cabinets are 1.2 mm sheet steel with formed welded seams, a return flange around doors and joints to prevent the passage of flame, a removable sump in the base, reversible shelves adjustable to 75 mm centres, and are designed to comply with the Flammable Liquid Storage Regulations 1972 as appropriate and HSE guidance HSG51 and CS19. The stocked range is 915 mm wide and 483 mm deep in four heights from 915 mm to 1,830 mm, from £1,268.10 inc. VAT. |
| Keep incompatible substances apart | Acid cabinets, agrochemical cabinets and the wider hazardous storage range | Separate cabinets for flammables, acids and pesticides in matching sizes, so segregation does not depend on shelf discipline inside one cupboard. |
| Gases under pressure: store securely, away from ignition sources | Gas cylinder cages, including lock-up cages and knock-down cages | Grenadier cages are angle-iron or 50 × 50 mm mesh construction; the carriers and lock-up cages have padlock provision and a highly flammable sign; the static and mobile carriers hold up to 16 Calor-type cylinders with a 720 mm usable height between shelves; lock-up cages hold cylinders with a retaining chain. The listings note a forklift is needed to unload them. Siting distances and separation from oxygen are covered in our gas cylinder storage regulations guide. |
| Petrol and Class A petroleum outdoors | Petroleum storage chests | Fully welded, designed and constructed to APEA requirements, suitable for Class A storage and labelled to the Petroleum (Consolidation) Act 1928, BS 5378 and Directive 92/58/EEC; sloping weather roof, removable sump, hasp and staple for a padlock. Three widths from £1,357.02 inc. VAT. |
| Bulk flammables or agrochemicals outside the building | Storage vaults | Designed to comply with the Flammable Liquid Storage Regulations 1972 as appropriate and HSG51; all-welded to APEA construction requirements; the listing states half an hour of protection from collapse and the passage of fire; a liquid-tight base; and an adjustable vent that meets flammable storage requirements closed and agrochemical requirements open. Three widths from £3,131.04 inc. VAT; a forklift is needed to unload. The polyethylene vaults (from £965.34) are listed as complying with the Oil Storage Regulations (England) 2001, which is the environmental rule for oil, not DSEAR. |
| Collect, contain and remove releases | Spill pallets and bunds, drum storage | Sump-based drum and IBC units and polyethylene spill pallets with lockable steel covers. What the law requires of bunding is set out in spill containment and bunding, and safe drum handling in storing oil drums safely. |
| Runaway exothermic events | Lithium battery storage and charging cabinets | DSEAR's scope includes similar energetic events such as runaway exothermic reactions, and whether a given battery store or charging area falls under it is a matter for your assessment. The GPC lithium-ion cabinets carry a reaction-to-fire classification to EN 1363-1 and EN 14470-1, with insulated shelves, a liquid-tight spill pallet and an integrated base so the unit can be moved to a safe location if damaged. Our guide to lithium battery storage cabinets covers what UK guidance expects. |
Five things a DSEAR assessment usually changes in a warehouse
Where the bulk is kept. The workroom holds what the shift needs in a fire-resisting cabinet; the bulk moves to an outdoor vault, chest or a dedicated store. This is the first item on the control hierarchy and usually the cheapest to implement.
Where the cylinders are. Gas cylinders come out of the corner by the roller door and into a cage that is outdoors, secured and signed, with fuel gases separated from oxidisers. The 2015 amendment means this applies to inert and oxidising cylinders as well as flammable ones.
What the charging area looks like. Battery charging for fork trucks and, increasingly, lithium-powered tools and vehicles is assessed for ventilation, ignition sources and what happens if a cell fails. Our guide to charging lithium batteries safely at work is the practical companion.
What happens on a spill. Sumps under cabinets, bunds under drums and IBCs, and a written procedure for a release rather than a mop and a hope.
Who knows. Staff can say what is in the cabinet, why it is locked, what the sign means and what to do if it leaks. That training duty is the one most often satisfied on paper and least often in the yard. The wider picture — segregating vehicles and pedestrians, racking inspections, PUWER and LOLER on the equipment — is in our warehouse health and safety guide.
A short DSEAR checklist for a storage-led site
List every dangerous substance with quantity and location, and keep the safety data sheets to hand. Decide what can be substituted or reduced. Put flammable liquids in fire-resisting cabinets sized to the quantity actually needed at the point of use, and move the rest to an outdoor store. Cage and sign every gas cylinder, secured against falling, outdoors where practicable and away from ignition sources and oxidisers. Provide sumps or bunds under anything that can leak, and a spill procedure. Keep incompatibles in separate cabinets. Decide, with competent help if the site warrants it, whether any area needs zoning, and if so specify the equipment in it accordingly. Write down the significant findings if you have five or more employees, brief the people who work with the substances, and review the assessment whenever the substances, quantities, layout or process change. None of this replaces the assessment itself, and none of it is advice on your particular site — it is the shape that DSEAR compliance takes when the risk is mostly about what is stored where.
Substances that are hazardous to health rather than just flammable are covered by COSHH instead — see our guide to the COSHH Regulations 2002 for the difference.
DSEAR works alongside general fire safety law. Our guide to the Regulatory Reform (Fire Safety) Order 2005 covers the responsible person’s duties and the fire risk assessment.