What is COSHH?

coshhCOSHH is the ‘Control of Substances Hazardous to Health’.

Why does it matter?

Using chemicals or other hazardous substances at work can put peoples’ health at risk. The COSHH Regulations require employers to control exposure to hazardous substances and to prevent the ill health of employees and others who may be exposed to hazardous substances in a work activity.

What is a hazardous substance?

Under COSHH Regulations a range of substances, including:

  • Chemicals
  • Products containing chemicals
  • Fumes
  • Dusts
  • Vapours
  • Mists
  • Nanotechnology
  • Gases
  • Biological agents (germs)
  • Germs that cause diseases such as Legionnaires’ disease


COSHH does not cover lead, asbestos, or radioactive substances because these have their own specific regulation.

What does COSHH require you to do?

  1. Assess the risks.
  2. Decide what precautions are needed.
  3. Prevent or adequately control exposure.
  4. Ensure control measures are used and maintained.
  5. Monitor exposure.
  6. Carry out appropriate health surveillance.
  7. Prepare emergency procedures.
  8. Ensure everyone is informed, instructed, trained and supervised in the use of hazardous substances.


The first possible control should be to consider avoiding use of the substance or substituting it for a safer one.

How to assess the risks

One of the key elements of COSHH is the requirement for a risk assessment.  You need to identify the hazardous substances present in your workplace and consider the risks they present to peoples’ health. It is important to remember that it is not just substances which have been supplied but also hazardous substances which may be produced by your work activities, such as fumes, vapours and waste materials. Based on this information, a judgement is required to determine how the hazardous substance will affect someone's health. The assessment will also need to determine who will be exposed and for how long. All findings should be recorded and reviewed, especially if there is a change in work practises, if there is reason to suspect that they are no longer valid, or where monitoring employees' exposure shows it is necessary.  

Decide what precautions are needed

If risks are identified then action is required to remove or reduce them to an acceptable level. If possible the hazardous substance should be substituted for a non-hazardous substance.

Control exposure

There are a number of ways to control exposure to a substance. This may include changing a process or activity, substitution, or using it in a safer form, such as a tablet rather than a powder.  Controlling exposure at source would include local exhaust ventilation (LEV), and reducing the number of people exposed and their exposure times. Also, as a last resort and not as a 
replacement for other control measures, is the use of PPE (personal protective equipment).

Control measures must be used and maintained

All employees must be given instruction, information, supervision and training in the control measures in place to ensure they are used and any defects are reported immediately. All controls must be maintained and be in a good state of repair to ensure their efficiency. 

Monitor exposure

If the risk assessment shows that control measures could deteriorate or fail, or that exposure limits may be exceeded, then it is necessary to have procedures to measure the concentration of the hazardous substance. In certain instances these should be alarmed to ensure that a failure is known.

Carry out appropriate health surveillance

If an employee could be exposed to a substance that has been linked to a particular disease or adverse health effect, it is sometimes necessary to carry out health surveillance, as stipulated in the Regulations.

Emergency procedures

If there is an accident, incident or other emergency involving a hazardous substance, then procedures must be in place to deal with such occurrences. This means setting up appropriate responses, warnings and communication, which need to be practised. The procedures must ensure that the affects of the hazardous substance are minimised immediately and that normal operation is resumed as soon as possible. Further information can be found in the Regulations and appropriate HSE guidance notes.

Information, instruction, training and supervision

All staff who work with a hazardous substance must have information, instruction, training and supervision about the substance and the risks it presents. They also need information about the risk assessment, control measures, correct use of PPE (personal protective equipment), health surveillance, and any emergency procedures.#

This guide is of a general nature; specific advice can be obtained from Assurity Consulting by calling tel. 01403 269375 or by email info@assurityconsulting.co.uk

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