COSHH knowledge centre

COSHH Regulations 2002 explained

Reviewed September 2026 · Written by Complys and checked against HSE and legislation.gov.uk guidance (sources below).

The Control of Substances Hazardous to Health Regulations 2002 set out a chain of duties, from assessing the risk through to controlling it, maintaining the controls, and checking they work. Here's what the key regulations require.

Assess the risk — regulation 6

You must not carry out work liable to expose employees to a hazardous substance unless you've made a suitable and sufficient assessment of the risk and put the necessary controls in place. The assessment must consider the substance's hazards, supplier information, the level and duration of exposure, any workplace exposure limit, and the effect of your controls.

Prevent or control exposure — regulation 7

Exposure must be prevented where reasonably practicable; where it can't be, it must be adequately controlled. Personal protective equipment is the last resort, used to supplement other controls — never the first or only line of defence.

The principles of good control practice (Schedule 2A)

Control counts as adequate only if the eight principles of good practice are applied, any workplace exposure limit isn't exceeded, and exposure to carcinogens, mutagens and asthmagens is reduced as low as reasonably practicable. The principles cover designing out emissions, all routes of exposure, proportionate and reliable controls, and reviewing that they keep working.

Maintain and use controls — regulations 8 and 9

Controls have to be properly used and maintained. Engineering controls such as local exhaust ventilation must be examined and tested at suitable intervals so they keep performing.

Monitor and check health — regulations 10 and 11

Where needed to ensure adequate control, exposure must be monitored; for certain substances and processes, health surveillance is required, with health records kept for 40 years. This is how you prove controls are working and catch harm early.

Inform and train — and record

Employees must be told about the risks and trained to use the controls (regulation 12). And where you employ five or more people, the significant findings of your assessment must be recorded — though writing it down is sensible whatever your size.

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Sources

This guide is general information, not legal advice. COSHH and chemical-classification rules change over time — always check the current HSE and legislation.gov.uk guidance for your work.

COSHH Regulations 2002 explained — FAQs

What do the COSHH Regulations require?

Assess the risk (reg 6), prevent or adequately control exposure (reg 7) using the principles of good practice, maintain and use the controls, monitor exposure and provide health surveillance where needed, and inform and train employees.

What is 'adequate control' under COSHH?

Control is adequate only if the Schedule 2A principles of good practice are applied, any workplace exposure limit is not exceeded, and exposure to carcinogens, mutagens and asthmagens is reduced as low as reasonably practicable.

Do I have to write my COSHH assessment down?

You must record the significant findings if you employ five or more people. HSE recommends recording it whatever your size.