US What DSEAR means
DSEAR stands for the Dangerous Substances and Explosive Atmospheres Regulations 2002, the Great Britain regulations that require employers and the self-employed to protect people from fires, explosions and similar events caused by dangerous substances at work. They are statutory instrument SI 2002/2776, and the Health and Safety Executive explains how to meet them in its Approved Code of Practice and guidance, L138.
DSEAR is where the workplace half of ATEX lives in British law. It brought the ATEX workplace directive 1999/92/EC into GB law, together with the safety parts of the chemical agents directive, and it stayed in force unchanged in substance after Brexit. Since 2015 it has also covered gases under pressure and substances that are corrosive to metals. Northern Ireland has its own, closely matching regulations.
The regulations apply to almost any workplace where a dangerous substance is present, from refineries and chemical plants to bakeries, joinery shops, paint stores, wastewater works and battery rooms. They sit alongside the general duty to manage risk under the Management of Health and Safety at Work Regulations. This page is a summary for people choosing equipment, not legal advice; the regulations and L138 are the authority.
What counts as a dangerous substance
HSE’s definition is broad. A dangerous substance is anything used or present at work that could harm people through fire, explosion or corrosion of metal if it is not properly controlled. In practice that includes:
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Flammable liquids. Petrol, solvents, paints, varnishes, inks and cleaning agents. Since the CLP flammable-liquid threshold rose to a flash point of 60 °C, diesel and gas oil are classed as flammable too.
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Flammable gases. LPG, natural gas, hydrogen, acetylene for welding and methane released at landfill sites.
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Combustible dusts. Flour, sugar, grain, wood, plastics and metal dusts from machining or sanding, which can explode when raised into a cloud.
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Hot or pressurised substances. High-flash-point liquids heated above their flash point, and gases held under pressure.
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Substances corrosive to metals. Acids and other chemicals that could weaken tanks, pipework or structures.
What DSEAR requires employers to do
The duties follow a logical order: understand the risk, remove or reduce it, then plan for the day something goes wrong. The table maps the main regulations to what they mean in practice.
| Regulation | Duty | In practice |
|---|---|---|
| 5. Risk assessment | Identify dangerous substances, the work involving them and how they could cause harm | The “DSEAR risk assessment”; significant findings are recorded where there are five or more employees |
| 6. Elimination or reduction | Remove the risk, or reduce it as far as reasonably practicable | Substitution first, then containment, ventilation, ignition control and mitigation |
| 7. Explosive atmospheres | Classify places into zones and choose equipment to suit | Zone drawings, equipment by category, EX signs at entry points where needed, explosion safety verified before first use |
| 8. Accidents and emergencies | Plan for incidents involving dangerous substances | Warning systems, emergency procedures and drills |
| 9. Information and training | Make sure people understand the risks and controls | Training, instructions and access to the assessment findings |
| 10. Containers and pipes | Identify hazardous contents | Labeling where contents are not otherwise clear |
| 11. Co-ordination | Co-operate where employers share a workplace | One co-ordinated approach on multi-employer sites |
Regulation 7 is the one that reaches equipment buyers. It is the reason a site has zone drawings and the reason a computer, display or switch going into a zoned area needs a hazardous area marking.
Zoning and equipment under DSEAR
Schedule 3 of DSEAR links each zone to an equipment category, the same categories used in the equipment rules. Category 1 equipment can be used in any zone, category 2 in Zones 1, 2, 21 and 22, and category 3 only in Zones 2 and 22. Equipment placed on the GB market must also meet the 2016 equipment regulations, so it carries a UKCA or CE mark with the Ex marking alongside.
The zone is only part of the match. The equipment’s gas or dust group must cover the substances on site, and its temperature class must sit below their ignition temperature. In broad terms, equipment already in use before July 2003 may stay in service if the risk assessment shows it is safe, but new equipment has to meet the current rules.
Installation and inspection matter as much as the marking. Electrical work in zoned areas is normally done to IEC 60079-14 and inspected to IEC 60079-17, and in the USA the technicians often hold CompEx certification. Details such as the right cable glands and earthing can make or break the protection.
What DSEAR means for computers and displays
For anyone specifying industrial computers, displays or network kit for a GB site, DSEAR turns into a short checklist.
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Start from the zone drawing. Ask the site for the zone, the gas or dust group and the temperature class at the exact installation point.
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Match the category and marking. Zone 2 needs category 3 equipment or better, shown in the marking as II 3G and an equipment protection level of Gc.
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Consider the safe area. A standard computer in a control room, linked by fiber or by intrinsically safe barriers, is often simpler than a certified one in the zone.
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Keep the certified configuration. Cables, docks, chargers, USB devices and mounting must follow the certificate, or the protection can be lost.
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Record it. Add the equipment, its certificate and its inspection schedule to the site’s DSEAR records.
Quick answers on DSEAR
DSEAR: common questions
What does DSEAR stand for?
Dangerous Substances and Explosive Atmospheres Regulations. The 2002 regulations cover fire, explosion and metal-corrosion risks from substances at work in Great Britain.
Is DSEAR a legal requirement?
Yes. DSEAR is law in Great Britain. Every employer or self-employed person with a dangerous substance at work must comply, starting with a risk assessment.
Who can carry out a DSEAR risk assessment?
A competent person. That can be someone in-house with the right knowledge or a specialist consultant. The duty stays with the employer either way.
How often should a DSEAR assessment be reviewed?
Regularly, and after any significant change. The regulations set no fixed interval, so many sites review on a set cycle and whenever processes, substances or layout change.
What is the difference between ATEX and DSEAR?
EU directives versus GB law. ATEX is the pair of EU directives. DSEAR is the GB law that implements the workplace one, while separate 2016 regulations cover equipment.
Our hazardous area panel PCs include ATEX Zone 2 and Class I, Division 2 models, and our rugged tablets include an ATEX and IECEx Zone 2 model for staff who move between areas. We work from your zone drawing and integrate and validate each system as standard, keeping within its certified configuration.