Most business owners who need a DSEAR assessment do not know the regulations exist. They have a spray booth, a wood dust extractor or a forklift battery charging bay, they have a fire risk assessment and they assume that covers it.
It does not. Here is why and how to tell whether you are caught.
What DSEAR is
The Dangerous Substances and Explosive Atmospheres Regulations 2002 are made under the Health and Safety at Work etc. Act 1974. They apply wherever a dangerous substance is present or liable to be present, at work.
The regulations require employers to:
- Assess the risks arising from dangerous substances
- Eliminate or reduce those risks, in a defined order of priority
- Classify hazardous places into zones where an explosive atmosphere may occur and mark them
- Ensure equipment and protective systems used in zoned areas are suitable
- Put in place arrangements for accidents, incidents and emergencies
- Provide information, instruction and training
- Identify the contents of containers and pipes
- Co-ordinate where more than one employer shares a workplace
They apply to the fire and explosion properties of substances. They are not about toxicity, which is COSHH and they are not about general fire precautions, which is the Fire Safety Order.
What counts as a dangerous substance
The definition is broader than people expect and it does not depend on quantity in the way many assume.
Broadly, a dangerous substance is:
- Any substance or mixture meeting the criteria for classification within a physical hazard class under the CLP Regulation, other than "corrosive to metals" and "gases under pressure"
- Any substance or mixture which because of its physico-chemical or chemical properties and the way it is used or present, creates a risk
- Any dust which can form an explosive mixture with air or an explosive atmosphere, whether in the form of solid particles, fibrous material or otherwise
That third limb catches a great many businesses that do not think of themselves as handling dangerous substances at all. Flour is a dangerous substance in a bakery. Wood dust is a dangerous substance in a joinery shop. Sugar, starch, custard powder, aluminium, magnesium, coal and a long list of other ordinary materials all form explosive dust clouds under the right conditions.
The second limb is the catch-all. A substance need not be classified under CLP if the way you use it creates a risk. Heating a substance above its flash point, atomising it or generating a mist all change the picture.
Common triggers
If any of the following applies to your premises, you should assume DSEAR is engaged until an assessment says otherwise.
Flammable liquids and solvents
- Spray booths and spray application of paints, lacquers, adhesives or coatings
- Solvent storage, decanting and dispensing
- Parts washers and degreasing baths using flammable solvents
- Printing: inks, solvent-based cleaning, blanket wash
- Cleaning with flammable solvents, including in food and pharmaceutical production
- Bulk storage of alcohol-based products, including hand sanitiser
- Waste solvent accumulation
Combustible dusts
- Joinery, cabinet making, sawmills: wood dust extraction, cyclones, silos, bag houses
- Bakeries, food processing, animal feed: flour, sugar, starch, milk powder, grain
- Metal working: grinding, polishing, cutting and shot blasting producing metal dust, especially aluminium, magnesium and titanium
- Plastics and rubber processing
- Biomass and wood pellet handling and storage
- Additive manufacturing using metal powders
Dust risk concentrates in the places nobody looks: inside extraction ductwork, in cyclones and filter units, in silos and hoppers and in accumulated layers on beams, ledges and light fittings. A layer of settled dust disturbed by a small primary explosion is what produces the secondary explosion that destroys buildings.
Gases
- LPG storage, use and forklift cylinder changing areas
- Acetylene and oxygen for welding and cutting
- Natural gas installations and gas trains on industrial plant
- Refrigerant gases in certain configurations
- Hydrogen from lead-acid battery charging. This is one of the most commonly missed triggers. Charging forklift and pallet truck batteries in an unventilated or poorly ventilated room generates hydrogen, which is explosive across an extremely wide concentration range
Fuels
- Petrol and diesel storage, dispensing and vehicle workshops
- Fuel oil tanks and bunded storage
- Generator day tanks
- Waste oil handling
Sectors that are almost always caught
Automotive body shops and vehicle repair, joinery and furniture manufacture, printing, industrial coating, food production, chemical blending, engineering and fabrication, waste and recycling, agriculture and grain handling, distilleries and breweries, laboratories and warehousing where flammable goods are stored.
Hazardous area classification and zones
Where an explosive atmosphere may occur, DSEAR requires the place to be classified into zones based on how likely an explosive atmosphere is and how long it persists.
For gases, vapours and mists:
| Zone | Meaning |
|---|---|
| Zone 0 | Explosive atmosphere present continuously, for long periods or frequently |
| Zone 1 | Explosive atmosphere likely to occur in normal operation occasionally |
| Zone 2 | Explosive atmosphere not likely in normal operation and if it does occur, will persist only for a short period |
For combustible dusts:
| Zone | Meaning |
|---|---|
| Zone 20 | Equivalent to Zone 0, as a cloud of combustible dust in air |
| Zone 21 | Equivalent to Zone 1 |
| Zone 22 | Equivalent to Zone 2 |
Zoned areas must be marked with the appropriate warning sign at points of entry.
Classification is not a formality. It determines what equipment can be used in the area and equipment intended for use in potentially explosive atmospheres must comply with the Equipment and Protective Systems Intended for Use in Potentially Explosive Atmospheres Regulations 2016, the successor regime to ATEX. Ordinary electrical equipment, standard light fittings, unprotected motors and non-classified extraction fans in a zoned area are a common and serious finding.
Classification also has practical commercial consequences. Getting the zone extents right, rather than defaulting to a conservative envelope, can be the difference between needing to replace an entire lighting installation and needing to replace three fittings.
How DSEAR sits alongside your fire risk assessment
There is genuine overlap here and it confuses people. Both regimes touch dangerous substances and both derive in part from the same European directives.
The Fire Safety Order covers the general fire precautions. It requires that:
- Where a dangerous substance is or is liable to be present, the fire risk assessment must include consideration of the matters in Schedule 1 Part 1. Those matters include the hazardous properties of the substance, safety data sheet information, quantities, interactions between substances, activities such as maintenance with high risk potential, the likelihood that an explosive atmosphere will occur and its persistence, the likelihood that ignition sources including electrostatic discharges will be present and become effective, the scale of anticipated effects and any places connected via openings to places where explosive atmospheres may occur. Article 9(2).
- The responsible person must eliminate or reduce risk from dangerous substances so far as is reasonably practicable and apply the control measures in Schedule 1 Part 4 in order of priority: reduce quantities to a minimum, avoid or minimise release, control release at source, prevent the formation of an explosive atmosphere including by appropriate ventilation and ensure any release is safely collected, contained or rendered safe. Article 12.
- No new work activity involving a dangerous substance may commence unless the risk assessment has been made and the required measures implemented. Article 9(8).
- Where two or more responsible persons share premises where an explosive atmosphere may occur, the responsible person with overall responsibility must co-ordinate the protective measures. Article 22(2).
DSEAR covers everything else: the detailed risk assessment of the dangerous substances themselves, hazardous area classification, equipment selection, explosion protection measures, control of ignition sources, mitigation such as explosion relief and suppression and the technical management of process safety.
In practice, the two documents should be produced with knowledge of each other. The fire risk assessment should record that a DSEAR assessment exists and reflect its findings. The DSEAR assessment should be consistent with the building's fire strategy and evacuation arrangements.
A fire risk assessment is not a DSEAR assessment and cannot substitute for one. If your assessor has recorded "flammable liquids stored in COSHH cabinet, satisfactory" and moved on, DSEAR has not been addressed.
Who enforces DSEAR
DSEAR is health and safety legislation, enforced by the Health and Safety Executive in most industrial and manufacturing premises and by the local authority in certain sectors under the Health and Safety (Enforcing Authority) Regulations 1998, typically retail, offices, warehousing and leisure.
The fire and rescue authority enforces the Fire Safety Order, including its dangerous substances provisions and will raise DSEAR matters where they see them, usually by referral.
Breaches are prosecuted under the Health and Safety at Work etc. Act 1974. The most serious carry unlimited fines and up to two years' imprisonment. Under the sentencing guideline for health and safety offences, fines are calculated by reference to culpability, seriousness of harm risked, likelihood of harm and turnover, which means penalties for larger organisations can be very substantial even where nobody was injured.
What a DSEAR assessment involves
- Identify every dangerous substance present or liable to be present, including those generated by process rather than purchased, such as dusts and vapours
- Gather data: safety data sheets, flash points, explosive limits, minimum ignition energies, dust explosibility data where available
- Understand the processes: where substances are released, in what quantity, how often and under what conditions
- Assess the risk, taking into account the Schedule 1 Part 1 matters and the DSEAR requirements
- Classify hazardous areas into zones, with drawings showing zone extents
- Review equipment in zoned areas against the required categories
- Assess ignition source control: electrical equipment, static, hot work, mechanical sparks, hot surfaces, smoking, vehicles
- Assess mitigation: ventilation, explosion relief, suppression, isolation, separation distances
- Review emergency arrangements, information, instruction and training
- Produce a prioritised action plan
For a small workshop with a single spray booth, this is a focused piece of work. For a multi-process manufacturing site it is a substantial project, often carried out area by area.
Common findings
- No assessment at all, on a site with obvious triggers
- Unclassified equipment in a zoned area, particularly lighting, fans and hand tools
- Battery charging rooms with no ventilation assessment and no zoning
- Dust accumulation on high level surfaces, which nobody cleans because nobody can reach it
- Extraction ductwork never internally inspected or cleaned
- Solvent stored in far greater quantities than the process requires
- No earthing or bonding when decanting flammable liquids
- Hot work permits absent or not enforced, particularly for contractors
- Zone drawings that exist but bear no relationship to the current plant layout
- Assessment carried out years ago, with three process changes since
Frequently asked questions
Is a DSEAR assessment a legal requirement? Yes, where dangerous substances are present or liable to be present at work. Regulation 5 of DSEAR requires a suitable and sufficient risk assessment and Article 9(2) of the Fire Safety Order separately requires your fire risk assessment to consider dangerous substances where they are present.
How much of a substance do I need before DSEAR applies? There is no simple threshold. What matters is whether an explosive atmosphere could form and whether a risk exists. A small quantity of a low flash point solvent decanted in a confined unventilated space can present a greater risk than a large quantity of a high flash point oil in a bunded tank outside.
Does DSEAR apply to wood dust? Yes, where the dust can form an explosive mixture with air. Joinery, sawmilling and furniture manufacture are among the most commonly affected sectors and extraction systems are usually the focus.
Does DSEAR apply to a lead-acid battery charging area? Almost always because charging generates hydrogen. The assessment usually focuses on ventilation rates, charger positioning, zoning around the charge point and control of ignition sources.
What about lithium-ion batteries? Lithium-ion failure is generally a fire and thermal runaway problem rather than an explosive atmosphere problem so it is usually addressed primarily through the fire risk assessment, storage separation and detection. DSEAR can still be engaged where vented gases could accumulate, for example in enclosed charging rooms or large storage installations. It is worth assessing rather than assuming either way.
Can my fire risk assessor do the DSEAR assessment? Sometimes but it is a distinct competence. Hazardous area classification in particular requires specific expertise. Ask directly whether the assessor is competent to carry out hazardous area classification and for evidence.
How often should a DSEAR assessment be reviewed? Whenever the process, substances, quantities, plant layout or ventilation change and periodically otherwise. Annual review is a reasonable default for an active production site.
