COSHH: meaning, assessment and the law
COSHH is the law on hazardous substances at work, from cement and solvents to silica dust and welding fume. This guide covers what it means, who it applies to and how a substance is assessed and controlled.
What is COSHH?
COSHH is the Control of Substances Hazardous to Health Regulations 2002, the GB law requiring employers to assess the risk from hazardous substances and prevent or adequately control exposure.
The letters stand for Control of Substances Hazardous to Health. The Regulations cover bought products such as paints, adhesives, resins and cleaners. They also cover what the work itself creates: dust from cutting and sanding, welding fume, diesel exhaust and harmful germs.
Before the work starts, the employer makes a “suitable and sufficient” assessment of the risk to health (regulation 6). Exposure is then prevented or, where that is not reasonably practicable, adequately controlled (regulation 7). Employers with five or more employees must record the significant findings.
The Regulations apply in England, Scotland and Wales, and Northern Ireland has its own. The COSHH Regulations 2002 page takes each regulation in turn.
What counts as a hazardous substance
Regulations 2 and 5Regulation 2 defines a “substance hazardous to health” in five ways. A substance needs to meet only one. Regulation 5 then sets out what COSHH leaves to other law.
Classified as a health hazard
Any substance or mixture that meets the criteria for a health hazard class under the CLP Regulation, whether or not it is actually classified. In Great Britain that means GB CLP, the retained version of Regulation (EC) No 1272/2008. In practice, most products with a health hazard pictogram on the label. See COSHH symbols.
Regulation 2(1)Given a workplace exposure limit
Any substance with a workplace exposure limit approved by HSE and listed in EH40/2005. Respirable crystalline silica, hardwood dust and Portland cement dust are all on the list.
EH40/2005Biological agents
Micro-organisms, cell cultures and human endoparasites that may cause infection, allergy or toxicity. On trade sites that means leptospirosis where rats are present, such as sewers and watercourses, and legionella in water systems.
Regulation 2(1)Any dust in quantity
Dust of any kind not already covered by the CLP or exposure limit tests. It counts at or above 10 mg/m³ of inhalable dust, or 4 mg/m³ of respirable dust, as an 8-hour time-weighted average.
Regulation 2(1)Anything else that creates a risk
Any other substance that creates a risk to health because of its chemical or toxicological properties and the way it is used or present at work.
Regulation 2(1)Made by the work, not bought
Dust from cutting stone or sanding wood, welding fume and diesel exhaust are made by the process. They come with no safety data sheet, so the employer finds the hazards from other reliable sources.
HSE L5, paragraph 69Outside COSHH
Lead and asbestos, where the Control of Lead at Work Regulations 2002 and the Control of Asbestos Regulations 2012 apply. Substances hazardous only because they are radioactive, explosive, flammable, hot, cold or under pressure. Medicines given in treatment. See asbestos RAMS.
Regulation 5How to do a COSHH assessment
Regulation 6A COSHH assessment, often called a COSHH risk assessment, follows the approach HSE sets out: identify, assess, control, record and review. It is made before the work starts, by someone competent to do it.
Identify the substances
List every product used and every process that gives off dust, fume, vapour, mist or gas. Read each label and current safety data sheet, and ask the supplier if in doubt.
NoteProcess substances count: HSE gives wood dust from sanding, silica dust from tile cutting and welding fume as examples.
Decide who is exposed and how
For each task, record whether the substance can be breathed in, get onto or through the skin, or be swallowed. Note how often and for how long, and who else is nearby.
NoteRegulation 6(2) lists what the assessment must consider, including the data sheet, any exposure limit, maintenance work and combined exposures.
Decide the controls
Work down the regulation 7 order: prevent exposure first, then control it, with PPE only where nothing else gives adequate control. Record why a step higher up is not reasonably practicable.
NoteL5 says carcinogens, mutagens and asthmagens give a more compelling reason to substitute.
Put the controls in place
Regulation 6(1) bars the work until the steps identified have been implemented, not just written down. L5 repeats that they must be in place before the work proceeds.
Record the significant findings
An employer with five or more employees must record the significant findings and the steps taken to meet regulation 7. The record can be written or electronic.
NoteL5 says the record should be proportionate: low-risk substances can share a single record.
Brief the team
Tell employees the substances, the risks, any exposure limit, the significant findings and the precautions to take. Give them access to the safety data sheets.
NoteRegulation 12 sets out what the information, instruction and training must include.
Review
Review regularly, and straight away if the assessment may no longer be valid, the work changes significantly or monitoring shows a need. Make the changes the review calls for.
NoteHSE also suggests a review after accidents, near misses or problems spotted by workers.
L5 says the assessor should know how the work uses or creates the substances, and have the authority to collect the information needed. The free COSHH assessment template follows these stages for one substance.
The COSHH hierarchy of control
Regulation 7Regulation 7 requires exposure to be prevented or, where that is not reasonably practicable, adequately controlled. It sets the order in which control measures are applied.
Prevent, by substitution first
Substitution is the preferred way to prevent exposure: replace the substance with one, or a process, that removes or reduces the risk. Water-based paint, pre-mixed mortar, pre-cut timber and isocyanate-free coatings are common examples.
Regulation 7(1) and (2)Processes, systems and engineering controls
Where prevention is not reasonably practicable, start with the design and use of work processes, systems and engineering controls, and suitable equipment and materials. A block splitter in place of a cut-off saw is one.
Regulation 7(3)(a)Control at source
Next, control exposure at source, with adequate ventilation systems and organisational measures. On-tool extraction, local exhaust ventilation and water suppression all work at the point the dust or fume is made.
Regulation 7(3)(b)PPE, in addition and last
Personal protective equipment comes only where adequate control cannot be achieved by other means, and it is added to the measures above, never instead of them. L5 says tight-fitting respirators should be face fit tested.
Regulation 7(3)(c)Measures that go with every level
Safe handling, storage and transport, including of waste. Maintenance procedures. The fewest people exposed, for the shortest time, with the least substance on site. General ventilation, and washing facilities.
Regulation 7(4)What adequate control means
Control counts as adequate only if the Schedule 2A principles of good practice are applied and any workplace exposure limit is not exceeded. Some substances must also be reduced to as low a level as is reasonably practicable. That covers anything carrying hazard statement H340, H350 or H350i, or listed in Schedule 1. It also covers anything carrying H334, listed in section C of HSE’s Asthmagen? review, or shown by the assessment to be a potential cause of occupational asthma.
Regulation 7(7) and Schedule 2AHardwood dusts are listed in Schedule 1, so regulation 2 treats them as a carcinogen. Staying under the 3 mg/m³ limit is not enough: exposure must be as low as is reasonably practicable. If exposure cannot be prevented, regulation 7(5) adds enclosure where reasonably practicable, no eating, drinking or smoking in contaminated areas, regular cleaning, warning signs and closed, labelled containers.
What employers must do beyond the assessment
Regulations 8 to 13The assessment decides the controls. Regulations 8 to 13 keep them working and keep people informed. Each is set out in full on the COSHH Regulations 2002.
Use of controls
The employer takes all reasonable steps to make sure controls are properly used. Employees make full and proper use of them and report any defect straight away.
Regulation 8Maintenance, examination and testing
Controls are kept in efficient working order and good repair. Local exhaust ventilation is thoroughly examined and tested at least once every 14 months, or more often for the Schedule 4 processes, and reusable RPE at suitable intervals. Records are kept for at least 5 years.
Regulation 9Monitoring exposure
Where the assessment shows it is needed, exposure is measured at regular intervals and after any change. Records of identifiable employees’ personal exposure are kept for at least 40 years from the last entry, others for 5.
Regulation 10Health surveillance
Health surveillance is required where appropriate. That includes where an identifiable disease or health effect may be linked to the exposure, is reasonably likely in the work, and valid, low-risk techniques can detect it. Health records are kept for at least 40 years. HSE guidance gives skin checks for cement work and annual lung function tests for isocyanate spraying as examples.
Regulation 11Information, instruction and training
Employees learn the substances, the risks, any exposure limits, the significant findings and the precautions. They get access to the safety data sheets and the results of monitoring. More in COSHH training.
Regulation 12Accidents, incidents and emergencies
Procedures are prepared for an accident, incident or emergency involving a hazardous substance, such as a serious spill, with first-aid facilities and safety drills tested at regular intervals. Only essential people enter the affected area, with suitable protective equipment. Where the quantities give only a slight, controlled risk, the planning duty falls away. The response duty stays for carcinogens, mutagens and biological agents.
Regulation 13Common hazardous substances on trade sites
From HSE guidanceThe substances electrical, mechanical, roofing, joinery, finishing, cleaning and construction teams meet most, with the controls HSE guidance describes. COSHH in construction starts with this list.
| Substance | Where it is met | Main risk | Typical controls |
|---|---|---|---|
| Cement, mortar and concrete | Mixing, laying, rendering, screeding and pours | Wet cement is highly alkaline and can cause serious burns, eye burns and dermatitis, irritant or allergic | Pre-mixed products, waterproof gloves suited to alkalis, boots high enough for pours, warm-water washing, skin checks |
| Silica dust | Cutting block, brick, kerbs, slabs and tiles; chasing and drilling concrete | Silicosis, COPD and lung cancer. Workplace exposure limit 0.1 mg/m³ as an 8-hour time-weighted average | Cut less, water suppression, on-tool extraction, face fit tested RPE, vacuum rather than sweep. See dust and silica RAMS |
| Wood dust | Sawing, routing and sanding in joinery, carpentry and fit-out | Asthma; hardwood dust is a Schedule 1 carcinogen with a 3 mg/m³ limit, which also applies to mixed wood dusts | Pre-cut materials, on-tool extraction with an M or H class unit, RPE of at least protection factor 20, such as FFP3, for most cutting and sanding |
| Solvents | Paints, thinners, strippers, adhesives and cleaners | Headaches, dizziness and irritation; unconsciousness or death at high levels in enclosed spaces; dermatitis | Water-based or low-solvent products, ventilation in every case, lids kept on, a vapour filter where RPE is needed, gloves matched to the product |
| Isocyanate paints and foams | Two-pack polyurethane paints and coatings, spray foam, glues and flooring | Occupational asthma, a significant risk when spraying; dermatitis; eye, nose and throat irritation | Isocyanate-free products, brush or roller rather than spray, ventilation, the correct gas or vapour filter, air-fed breathing apparatus for spraying, annual lung function testing where aerosols are made |
| Welding fume | Welding and hot cutting in fabrication, M&E and steelwork | HSE states all welding fume can cause lung cancer; also asthma | Cold joining where possible, low-fume methods, local exhaust ventilation, RPE, good general ventilation. See hot works RAMS |
| Diesel exhaust | Generators, plant and vehicles in tunnels, car parks and enclosed areas | Eye and airway irritation, coughing and breathlessness; HSE notes some evidence of lung cancer after about 20 years of repeated exposure | Engines off when not needed, tailpipe exhaust extraction, good ventilation, engines kept serviced, RPE only as a last resort |
| Cleaning chemicals | Disinfectants, bleach, descalers and degreasers in cleaning and facilities work | Contact dermatitis; corrosive products cause skin burns and eye damage; some ingredients cause asthma | Products used as the label and data sheet direct, gloves and eye protection, acids and caustics stored apart, early skin symptoms reported. See cleaning RAMS |
| Biocides | Wood preservatives, disinfectants, insecticides and rodenticides | Harm to the user and anyone nearby if not used as the label directs; the hazard depends on the product | Use only for the purpose on the label, wear the protection the label sets, restrict access during and after treatment |
Every product still needs its own assessment from its safety data sheet. Lead work comes under its own regulations, not COSHH: see lead at work. Two diseases have their own pages: occupational asthma and occupational dermatitis. The pre-filled COSHH risk assessment template covers these substances for site and workshop work.
Assessment, register, data sheet and RAMS
Four documents get called “the COSHH” on site. The Regulations name two of them: the assessment and the supplier’s safety data sheet.
The COSHH assessment is the regulation 6 assessment for a substance or task. A COSHH register is the list of every hazardous substance held, with its data sheet and assessment. The Regulations do not mention a COSHH register, but a register is a practical way to show every substance has been assessed.
The safety data sheet comes from the supplier and describes the product. It feeds the assessment, but it is not one. See safety data sheets for the sections that matter.
A RAMS covers the whole task, so it refers to the COSHH assessments for the substances used. The COSHH risk assessment template is written as a RAMS for site work.
Every data sheet to hand,
tied to the job that uses it.
In Unibuild, each hazardous substance holds its safety data sheet and its supplier, linked to the jobs, materials and purchase orders that use it. Review dates are tracked, every version is kept, and the current one is the one out on site.
When an auditor or a principal contractor asks for the COSHH register, it is a search by name or supplier, not a spreadsheet somebody else kept.
- A data sheet for every substance held with its supplier
- Tied to the job through the materials and purchase orders that use it
- Review dates tracked and every version kept
- Searched by product name or supplier
Free COSHH templates
Free to use and reuse, no sign-upWhat does COSHH stand for?
What is a COSHH assessment?
Who is responsible for COSHH?
Does a COSHH assessment have to be written down?
How often should a COSHH assessment be reviewed?
Does COSHH apply to the self-employed?
What is not covered by COSHH?
What is the COSHH hierarchy of control?
Is a COSHH register a legal requirement?
Is COSHH training a legal requirement?
The COSHH guide
Read in any orderSources
Great Britain law and HSE guidance, read on the dates above. Northern Ireland has its own COSHH Regulations.
- The Control of Substances Hazardous to Health Regulations 2002, legislation.gov.uk
- COSHH regulation 7 and Schedule 2A, legislation.gov.uk
- L5 Control of substances hazardous to health, ACOP and guidance, sixth edition 2013, HSE
- INDG136 Working with substances hazardous to health, HSE
- How to carry out a COSHH risk assessment, HSE
- Self-employed prescribed undertakings, SI 2015/1583, legislation.gov.uk
- The GB CLP Regulation, HSE
- EH40/2005 Workplace exposure limits, HSE
- Construction hazardous substances: cement, solvents, isocyanates and dust, HSE
- Welding fume: protect your workers, HSE
- INDG286 Diesel engine exhaust emissions, HSE
The COSHH register,
tied to the job.
Unibuild keeps each substance’s data sheet and supplier against the jobs, materials and purchase orders that use it, with review dates tracked and every version kept.