Control of substances hazardous to health: COSHH

Article reference: UK-IA-HSE04
Last updated: December 2020 | 4 min read

Chemicals or hazardous substances can damage people’s lives. Using them at work puts workers’ health at risk. The law therefore, requires employers to control exposure to hazardous substances to prevent ill health.

From 6 April 2005, a better practice and focus on health has helped employers meet their duties under the Control of Substances Hazardous to Health Regulations (COSHH). Prior requirements have been clarified, modified and amended and have been brought together by the introduction of eight principles that apply regardless of whether or not a substance has an "Occupational Exposure Limit".

The eight principles are similar to those for other workplace risk assessments:

  • Assess the risks

  • Decide what cautionary measures are needed and put them into action

  • Control exposure by measures that are proportionate to the health risk

  • Ensure that measures are used and maintained. Cary out checks where necessary

  • Monitor the exposure - where adequate control of exposure cannot be achieved provide for suitable personal protective equipment

  • Check and review regularly whether all elements of control measures are effective

  • Inform and train all employees on the hazards and risks from the substances with which they work and the use of control measures developed to minimise the risks. Prepare procedures to deal with accidents

  • Ensure all workers are trained and supervised appropriately

By following the regulations, you should:

  • improve productivity within the business

  • improve employee morale

  • your employees will better understand health and safety issues


Failure to comply with the regulations and not controlling hazardous substances will result in a higher possibility of your employees becoming ill. Whether they work more slowly because of an eye infection, take time off because of chronic lung disease, or suffer a fatality, your business will suffer.

It will leave you liable to enforcement action including prosecution under the COSSH regulations. It may also result in civil claims from your employees.

Which substances are hazardous to health?

Under COSHH, a number of substances are classed hazardous to health. They include, but are not limited to:

  • Substances or mixtures of substances classified as dangerous to health under the chemicals regulations. They can be identified by their warning label. Additionally, the supplier must provide a data sheet for them, which will help to identify them. A list of commonly used dangerous substances can be supplied to you by the HSE.

  • Substances that are not listed in the above publication should be labelled accordingly, if deemed dangerous by the supplier

  • Substances with exposure limits are listed in the HSE publication “EH40/2005 Workplace Expose Limits

  • Biological agents (bacteria and other micro-organisms), if directly connected with the work, such as in the farming industry, sewage treatment, or healthcare, or if the exposure is incidental to the work

  • Any dust, if the concentration in the air exceeds the limits set by COSHH

  • Any other substance which creates a risk to health, but which for technical reasons may not be specifically covered by CHIP, including:

    • Asphyxiates (gases such as argon and helium, which are not themselves dangerous, but do however, endanger life by reducing the amount of oxygen available in the air

    • Pesticides

    • Medicines

    • Cosmetics

    • Substances produced in chemical processes

Which substances are not covered by COSHH?

Almost all hazardous substances are covered by COSHH; however, the following are not:

  • Asbestos, which has its own regulations.

  • Substances that are hazardous only because they are radioactive, at high pressure, at extreme temperatures or have explosive or flammable properties. These substances have their own regulations too.

Joint responsibility with your employees

As an employer, you have a duty of care to your employees and fellow workers. You must apply the eight directions and ensure that they are adhered to.

Additionally, however, under the wider guidelines of health and safety law, all workers have a duty of care to fellow workers. This means that although training should be provided by the employer, an employee must take steps to apply the training and take reasonable care of others in order to prevent accidents from occurring.

Employees must also see to it that when they are employed they get the above privileges as a matter of right. Employees should request that the regulations are put in place, and if necessary, seek further action so that they are complied with. Thus both the employer and the employee should keep in mind that it is their benefit that the principles are implemented.

Further information

You may also want to read about the Management of Health and Safety of Work Regulations, which also apply.

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