Dangerous Substances & Explosive Atmospheres Regs 2002

Where can it
form, and what
would light it?

That is the whole of DSEAR in one question. If you store, use or produce anything that can burn or explode, you are required to answer it in writing.

We write assessments that survive an inspection: substances, zones, ignition sources, controls, and a numbered action list you can actually work through.

HIGH-LEVEL VENT LOW-LEVEL VENT ZONE 0 vapour space in the drum ZONE 1 ZONE 2 INDICATIVE ONLY · ACTUAL EXTENTS DEPEND ON RELEASE RATE, VENTILATION AND SUBSTANCE
01 — Zoning around a solvent drum store
2003In force since
NoMinimum quantity
5 daysReport turnaround
UKSite work anywhere

Does this apply to you?

If you tick any one of these, you are in scope. It is not a sliding scale, and there is no threshold quantity written into the regulations.

A single 205‑litre drum of solvent in a workshop brings you in, in exactly the same way a tank farm does. What changes is the depth of assessment that is reasonable, not whether you need one.

01

Flammable liquids

Solvents, thinners, fuels, adhesives, alcohol. Drum stores, decanting areas, dip tanks, parts washers.

02

Gases and LPG

Bulk tanks, cylinder stores, forklift refuelling points, acetylene, natural gas plant rooms.

03

Combustible dust

Flour, sugar, wood, grain, animal feed, metal powders. Extraction, silos, sanding bays.

04

Spraying and coating

Paint booths, powder coating, printing, aerosol filling, mixing rooms.

05

Fuel storage

Depots, farm tanks, generator day tanks, forecourts, marina bunkering.

06

Battery charging

Lead‑acid charging bays vent hydrogen. The one most warehouses miss entirely.

PEMBROKESHIRE ST BRIDE’S BAY South Hook LNG Dragon LNG Valero Pembroke Refinery RWE Pembroke Power Station Port of Milford Haven NEYLAND we are here SCHEMATIC · NOT TO SCALE
02 — The energy cluster on our doorstep
Milford Haven, Pembrokeshire

Based on the Milford Haven Waterway

Pembrokeshire County Council calls this the Energy Capital of the UK, and it is not marketing.

Two LNG terminals, an oil refinery, one of Europe’s largest gas‑fired power stations and a working deep‑water port sit within a few miles of our door. That is the environment DSEAR was written for, and it is the one we work in week in, week out.

The supply chain around that waterway — tank cleaning, coatings, fabrication, marine fuel, haulage — handles dangerous substances every day. We travel UK‑wide for site work, but the grounding is real, and it is why our zoning drawings tend not to come back with questions.

The zone decides the equipment

Get it too tight and you fail an inspection. Get it too generous and you spend thousands on ATEX kit you never needed.

Both mistakes are expensive. The second one is far more common, and nobody ever tells you about it, because the person selling you the equipment has no reason to.

How zones map to equipment categories →

ZONE 0ZONE 20 (dust) Present continuously, for long periods, or frequently inside a drum, a tank, a filter CAT 1 ZONE 1ZONE 21 (dust) Likely to occur occasionally in normal operation around vents, fill points, change points CAT 2 ZONE 2ZONE 22 (dust) Not likely in normal operation, and brief if it happens the wider floor of a ventilated store CAT 3
03 — Zone to ATEX category

What you get

A

A written DSEAR assessment

Substance inventory, hazard identification, ignition source review, existing controls, and the risk that is left once those controls are counted.

B

Hazardous area classification

Zone 0, 1, 2 for gas and vapour, 20, 21, 22 for dust, with a marked‑up drawing you can hand straight to an electrical contractor.

C

A prioritised action list

Numbered, dated and ranked. Not a wish list. You will know what to do on Monday and what can wait until the next shutdown.

D

A phone call to talk it through

Included. A report nobody understands is a report nobody acts on, and that is what gets people prosecuted.

On site

One assessor, on your site, writing the report.

Not a sales visit followed by a template. You deal with the person who walked your building, start to finish, and you can ring them afterwards.

Photo slot — assessor on site
send us a real photo and it drops straight in

Common questions

Who needs a DSEAR risk assessment?

Any UK employer whose work involves a dangerous substance. That covers flammable liquids, gases, LPG, solvents, paints, aerosols, and combustible dusts such as flour, wood, sugar or metal powder. There is no minimum quantity written into the regulations. A single 205-litre drum of solvent in a workshop brings you into scope.

Is DSEAR a legal requirement?

Yes. The Dangerous Substances and Explosive Atmospheres Regulations 2002 have been in force since July 2003 and are enforced by the HSE. The duty to assess sits with the employer, and it cannot be delegated to a supplier or a landlord.

How long does a DSEAR assessment take?

Most single-site assessments take half a day to a full day on site. The written report follows within five working days. Larger or multi-building sites are quoted after a short scoping call.

What is the difference between DSEAR and hazardous area classification?

Hazardous area classification is one part of DSEAR. It is the exercise of working out where an explosive atmosphere could occur and dividing those places into zones. The DSEAR assessment is the wider piece: substances, ignition sources, controls, mitigation and emergency arrangements.

Do I need to redo it?

Review it when the assessment is no longer valid. In practice that means when you change a substance, a process, the layout, the ventilation or the equipment. Otherwise a review every two to three years is the normal benchmark.

Tell us what you store and we'll tell you where you stand

No charge for the conversation. Most quotes go out the same day.