COSHH stands for the Control of Substances Hazardous to Health Regulations 2002. It is UK law that sets out how employers must manage risks from hazardous substances at work. It covers both health risks and the steps needed to prevent harm.

COSHH sits alongside wider health and safety duties. It links with the Health and Safety at Work etc. Act 1974 and the Management of Health and Safety at Work Regulations 1999. The core point stays the same. Employers must protect workers from harm caused by substances used or created at work.

Who COSHH Applies To

COSHH applies to most workplaces where hazardous substances are present. It covers offices, warehouses, sites, labs, kitchens, care settings and workshops. It applies whether the substance is bought in or made during work.

COSHH can apply to:

• Substances used in tasks, such as cleaning products, paints and solvents
• Dusts and fumes from work, such as wood dust, welding fume and silica dust
• Biological agents, such as bacteria and viruses, where work creates exposure risk
• Mists, vapours and gases released during processes or maintenance

COSHH does not cover every hazard. It does not cover asbestos or lead in the same way, as these have their own rules. It also does not cover risks from substances that are only hazardous because they are hot or cold.

Employer Legal Duties Under COSHH

Under COSHH, employers must take a structured approach. Identify substances. Assess risk. Put controls in place. Check that they work. Keep workers informed.

Identifying Hazardous Substances

Employers must identify substances that can harm health. This includes substances with hazard labels and substances that cause harm through exposure over time.

This step often starts with:

• A list of substances used on site
• Safety Data Sheets (SDS) from suppliers
• A review of tasks that create dust, fume or mist
• Input from supervisors and workers who do the task

Carrying Out COSHH Risk Assessments

A COSHH assessment looks at how people could be harmed and how likely it is. It focuses on exposure. That means what gets into the body and how.

A suitable assessment usually covers:

• The substance and its health effects
• Who is exposed and how
• How the substance is used, stored and moved
• Current controls and gaps
• Actions needed to reduce risk

The assessment must be practical. It must match the work. It must be reviewed when tasks change, when controls fail or after an incident.

Preventing or Controlling Exposure

COSHH expects employers to prevent exposure where possible. If prevention is not possible, exposure must be controlled. Controls should reduce risk so far as reasonably practicable.

Common control measures include:

• Substitution, such as using a less harmful product
• Enclosure of the process
• Local exhaust ventilation (LEV)
• Safe systems of work, including limits on time and quantity
• Good housekeeping to reduce dust build-up
• Suitable storage and clear labelling

Personal protective equipment (PPE) can have a role. It should not be the only control unless other controls cannot achieve enough reduction. PPE must be suitable, fitted and maintained.

Providing Information, Instruction and Training

Employers must ensure workers understand the substances they work with and the controls in place. This includes giving clear instructions for safe use, storage and disposal. It includes telling workers what to do if something goes wrong. It also includes providing COSHH training that matches the tasks and the risks.

This duty applies to direct employees and others who may be affected, such as contractors, agency staff and cleaners.

Health Surveillance Where Required

In some cases, COSHH requires health surveillance. This is needed where there is a known risk of disease and where checks can detect early signs.

Examples include:

• Dermatitis risk from wet work and chemicals
• Asthma risk from sensitising substances
• Exposure to certain biological agents
• Work where monitoring is set out in guidance or industry practice

Health surveillance should be planned. It should be carried out by competent people. Findings should feed back into controls and risk assessments.

Reviewing and Updating Controls

Controls must not stay on paper. Employers must check they work in real conditions. If controls fail, action must follow.

Reviews are needed when:

• A new product is introduced
• The process changes
• A worker reports symptoms
• An incident happens, such as a spill or leak
• There is reason to suspect controls are no longer effective

Records should show what was checked, what was found and what was changed.

COSHH Training Requirements Explained

COSHH training is part of the wider duty to manage risk. It is not a single event. It must match the work and change when the work changes.

Who Needs COSHH Training

Any worker who may be exposed to hazardous substances needs suitable training. This includes those who use chemicals and those who may be exposed through nearby work.

This can include:

• Cleaners and facilities staff
• Maintenance teams
• Production staff
• Lab staff
• Site workers and trades
• Supervisors who plan or check the work

Training needs may differ by role. A person who mixes chemicals needs more detail than a person who only handles sealed containers.

What COSHH Training Must Include

Training should focus on what workers need to do their job safely. It should cover the hazards, the controls and the limits of those controls.

Key content often includes:

• What the substance is and how it can harm health
• Routes of exposure, such as breathing in, skin contact and ingestion
• Control measures in place and how to use them
• Safe handling, storage and disposal
• Spill response and first aid steps
• What to do if symptoms appear or controls fail

The Last Check Before the Shift Starts

COSHH compliance often fails at the point of work. The plan exists but the controls are not used or are used wrong. A final check keeps it real.

Before exposure can happen, employers and supervisors should be able to answer:

• Has the COSHH assessment been reviewed for this task
• Are controls in place and working
• Do workers know the key steps and the stop points
• Is the right PPE available and being used right
• Is there a clear response plan for spills, leaks or symptoms

That last check often prevents the call-out, the sick note and the investigation.