Health & Safety Guidance
Dust in the workplace
Dust is a hazard in construction, manufacturing, woodworking, food processing, quarrying and mining — and it carries two separate risks with two separate legal duties. One damages lungs over years. The other can destroy a building in seconds.
LEV, RPE & housekeeping
Health surveillance
Workplace dust is made up of fine solid particles suspended in the air. Depending on the source it may contain respirable crystalline silica, hardwood or softwood particles, metal, flour, grain, sugar, cement or chemical residues. Prolonged exposure causes serious and often irreversible respiratory disease, and some dusts will ignite and explode when dispersed as a cloud.
This guidance covers both strands: controlling exposure so people do not become ill, and controlling explosive atmospheres so a dust cloud does not find an ignition source.
Dust is two duties, not one. The split is by type of harm, not by type of substance. Dust that is hazardous to health falls under COSHH. Dust that is dangerous by reason of fire and explosion falls under DSEAR.
Wood dust is the clean example of why this matters: the same material carries a carcinogen risk under COSHH and an explosion risk under DSEAR, and a COSHH assessment does not discharge the DSEAR duty. Silica, by contrast, is a serious health hazard but is not combustible — so it is a COSHH problem only.
Main hazards associated with dust
COSHH
Respiratory disease
Occupational asthma, chronic obstructive pulmonary disease, silicosis and, with hardwood dust, nasal cancer. Damage builds silently over years and is usually permanent by the time symptoms appear.
DSEAR
Fire and explosion
Wood, flour, grain, sugar, animal feed, metal powders, plastics and coal will all explode when dispersed as a cloud in the right concentration and ignited. Settled layers are the fuel store for a second, larger event.
Contact
Skin irritation
Irritant and allergic contact dermatitis, particularly with cement, resins, flour and some hardwoods. Often dismissed as dry skin until it becomes chronic.
Contact
Eye injury
Irritation, abrasion and, with high-velocity particles from cutting or grinding, penetrating injury. Goggles rather than safety spectacles where dust is airborne.
Controlling the health risk
Under COSHH the duty is to prevent exposure where reasonably practicable, and where it is not, to control it adequately. Respiratory protective equipment is the last line, not the first — it protects only the person wearing it, only while worn correctly, and only if it fits.
- Eliminate or substitute first: order materials cut to size, use pre-mixed products, choose lower-dust methods.
- Suppress at source with on-tool water suppression or on-tool extraction before considering general ventilation.
- Install local exhaust ventilation designed for the process, and have it thoroughly examined and tested — for most processes this must be at least every 14 months.
- Provide suitable personal protective equipment, including correctly specified RPE and goggles.
- Face fit test tight-fitting RPE for each wearer, and re-test if the face changes shape or the mask model changes. A beard defeats a tight-fitting mask.
- Clean with wet methods or a vacuum with the appropriate filtration class. Never dry sweep, and never blow dust down with compressed air.
- Monitor exposure where required and keep records. Provide health surveillance for those at risk, so early damage is caught while it still matters.
Controlling the explosion risk
A dust explosion needs five things present together: combustible dust, oxygen, an ignition source, dispersion of the dust as a cloud, and enough confinement for pressure to build. Remove any one and the explosion cannot occur — which is what a DSEAR assessment is actually for.
The secondary explosion is usually the one that kills. A small primary event inside a duct, hopper or mill produces a pressure wave that lifts settled dust off beams, ledges, cable trays and roof voids. That newly airborne dust then ignites, and the second explosion is typically far larger than the first because it involves the whole building rather than one vessel.
This is why housekeeping is an explosion control and not just tidiness. Surprisingly thin layers on overhead surfaces hold enough fuel to matter once they are disturbed.
Practical control under DSEAR normally means:
- A risk assessment under Regulation 5 that identifies the dangerous substances, where explosive atmospheres can form, and how likely and persistent they are.
- Classification of those places into dust zones 20, 21 and 22 according to how often and for how long an explosive atmosphere is present.
- Equipment and protective systems selected to match the zone, correctly rated and labelled — including the things people forget, such as portable tools, lighting and vacuum cleaners.
- Control of ignition sources: hot work, mechanical sparks, overheated bearings, static discharge, smoking and tramp metal entering a mill.
- Explosion protection where prevention alone is not enough — venting, suppression, isolation and containment.
- Housekeeping regimes that remove settled dust from high level as well as floor level, using methods that do not themselves raise a cloud.
- Recorded findings, marked hazardous places, and coordination where contractors work in your zoned areas.
HSE guidance HSG103 covers precautions against dust explosions, and L138 is the DSEAR Approved Code of Practice and guidance.
Dust is not the only DSEAR trigger. The same regulation covers flammable gases, solvent vapours and flammable liquids, and the assessment works differently: gas and vapour zoning turns on flash point, evaporation rate and how far a release travels, rather than particle size, dispersion and settled layers. A site that mills timber and also stores solvents has two DSEAR problems, not one. The DSEAR gas and liquid explosion risk assessment course covers that side.
IIRSM approved
DSEAR Dust Explosion Risk Assessment
Duty-holder level — e-learning
Dust explosion behaviour, hazard identification, the hierarchy of control, hazardous area classification and zoning, equipment selection against the zone, and recording a defensible assessment under Regulation 5.
IIRSM approved
DSEAR Gas and Liquid Explosion Risk Assessment
Duty-holder level — e-learning
The companion course for flammable gases, solvent vapours and liquids. Release and ignition scenarios, hazardous area classification for gases and vapours, equipment selection, and a defensible Regulation 5 assessment.
Legal requirements
Employers have duties under the Health and Safety at Work etc. Act 1974, the Control of Substances Hazardous to Health (COSHH) Regulations 2002, the Management of Health and Safety at Work Regulations 1999 and, where dust is combustible, the Dangerous Substances and Explosive Atmospheres Regulations 2002. Suitable and sufficient risk assessments and proportionate control measures must be in place and acted upon — an assessment filed and forgotten is not compliance.
Not sure where your gaps are? Identify risks and improve safety with a Health and Safety Risk Review for businesses.
Training and competence
Everyone exposed to dust needs to understand the risk, the controls and why the controls exist — people defeat extraction and remove masks when the reason has not been explained. Duty holders need more than awareness.
Awareness
Silica Dust Awareness
Respirable crystalline silica, the tasks that generate it and the controls that work. For anyone cutting, grinding or drilling stone, concrete, brick or engineered worktops.
Duty holder
Silica Dust for Duty Holders
The management-level view: assessing exposure, selecting and maintaining controls, health surveillance and the records that need to exist when an inspector asks.
Duty holder
LEV Management for Duty Holders
Specifying, commissioning, checking and maintaining local exhaust ventilation, including thorough examination and test intervals and what a logbook needs to show.
IIRSM approved
DSEAR Dust Explosion Risk Assessment
The explosion side of the duty rather than the health side: zoning, ignition control, equipment selection and a defensible Regulation 5 assessment.
IIRSM approved
DSEAR Gas and Liquid Explosion Risk Assessment
For sites where solvents, flammable liquids or gases sit alongside the dust problem. Same regulation, different physics, separate assessment.
Practical
Face Fit Testing
Carrying out fit tests on tight-fitting RPE. Unfitted masks are one of the most common reasons dust controls fail in practice while appearing to be in place.
Hub
COSHH Training
The full range of COSHH courses, from awareness for those exposed through to assessor-level training for those writing the assessments.
Frequently asked questions
Does a COSHH assessment cover dust explosion risk?
No. COSHH deals with substances hazardous to health; DSEAR deals with substances dangerous by reason of fire and explosion. Where a process generates combustible dust, both sets of regulations apply and each needs its own assessment. A thorough COSHH assessment can control exposure perfectly well while leaving the explosion risk entirely unexamined.
Which dusts are explosive?
Broadly, any organic or metallic dust fine enough to form a cloud: wood, flour, grain, sugar, starch, milk powder, animal feed, coal, rubber, many plastics and pharmaceutical powders, and metals such as aluminium and magnesium. Silica, cement and most mineral dusts are not combustible — they are a health problem rather than an explosion problem. If you are unsure about a specific material, explosibility testing gives a definitive answer.
Our site handles solvents as well as dust — is that the same DSEAR assessment?
The regulation is the same but the assessment is not. Dust zoning uses zones 20, 21 and 22 and turns on particle size, dispersion and the depth of settled layers. Gas and vapour zoning uses zones 0, 1 and 2 and turns on flash point, evaporation rate and how far a release disperses before it dilutes below the lower explosive limit. Equipment selection differs accordingly. A coatings plant with a powder line and a solvent store needs both strands assessed, and training that covers only one leaves the other unexamined. The DSEAR gas and liquid course covers the vapour side.
How much settled dust is too much?
Less than most people expect. A layer thin enough to write your name in, spread across beams, ledges, ductwork and roof voids, can supply the fuel for a destructive secondary explosion once a pressure wave lifts it. Treat visible accumulation on high-level surfaces as a finding to act on rather than a housekeeping preference, and clean by methods that do not raise a cloud.
Is dry sweeping or blowing down with compressed air ever acceptable?
Both take dust that had settled and put it back into the air, which is precisely what you are trying to avoid on both counts — it raises exposure and, with combustible dust, creates a cloud. Use wet methods or a vacuum of the appropriate filtration class instead.
Is a dust mask enough on its own?
No. RPE sits at the bottom of the hierarchy because it protects only the wearer, only while worn, and only if it fits and is the right specification for the dust. Control at source — different method, water suppression, on-tool extraction, LEV — protects everyone in the area whether or not they remember to put something on.
How often must LEV be examined?
For most processes, thorough examination and test must be carried out at least every 14 months, and more frequently for certain higher-risk processes. That is a maximum interval rather than a target — routine checks, filter changes and a maintained logbook sit between examinations, and a system that has been altered should be reassessed rather than left until the next date falls due.
Who needs health surveillance for dust exposure?
Where there is an identifiable disease linked to the exposure, a reasonable likelihood it will occur under the conditions of work, and valid techniques for detecting it. In practice that commonly means workers exposed to respirable crystalline silica, wood dust, flour and grain dust, and other respiratory sensitisers. The point is early detection — finding a change while it can still be acted on, rather than confirming damage after the fact.
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This page is general guidance and does not replace COSHH, DSEAR, the relevant HSE Approved Codes of Practice, or your own risk assessments.