Health & Safety Department


Guidance and advice on the Control of Substances Hazardous to Health Regulations 2005

Duties and compliance

The COSHH Regulations impose duties on the University to protect its staff and any other persons, whether at work or not, who may be affected by the hazards of the University's work involving substances hazardous to health, including biological agents.

The Regulations, and compliance with them, as with any other health and safety legislation, must constitute an integral part of the management system of the University’s Schools, Departments, or similar Management Units; compliance with the Regulations not only ensures compliance with the law, but will prevent incidence of ill health, ensure best working practice and will encourage the evolvement of a health and safety culture within the organisation, whereby our students will be taught by example, the best standards of health and safety.

In order to ensure compliance with the Regulations Heads of School, or similar Management Units, must ensure that work is not undertaken that is liable to expose any employees, or others, to any substance hazardous to health unless suitable and sufficient assessment of the risks created by that work has been undertaken and suitable and sufficient control measures identified and implemented so as to reduce the risk to the lowest level reasonably practicable.

Eight principles of good practice

The Regulations introduce eight principles of good practice that will apply regardless of whether a substance has been assigned a WEL. According to HSE, employers who do not follow these eight principles will, by implication, not be properly protecting their employees. The principles are:

  • Design and operate processes and activities to minimise emission, release and spread of substances hazardous to health.
  • Take into account all relevant routes of exposure - inhalation, skin absorption and ingestion - when developing control measures.
  • Control exposure by measures that are proportionate to the health risk.
  • Choose the most effective and reliable control options, which minimise the escape and spread of substances hazardous to health.
  • Where adequate control of exposure cannot be achieved by other means, provide, in combination with other control measures, suitable personal protective equipment.
  • Check and review regularly all elements of control measures for their continuing effectiveness.
  • 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.
  • Ensure that the introduction of control measures does not increase the overall risk to health and safety.

Workplace Exposure Limits and EU hazard and precautionary statements

The COSHH Regulations reference Workplace Exposure Limits, a full list of which can be found in EH40/2005 Workplace exposure limits (downloadable free from the HSE website), which are maximum concentrations of airborne substances averaged over a reference period, to which employees may be exposed by inhalation. These are time-weighted averages of either long term (8hours) or short term (15 minutes).

If proper control measures are in place, no employee should be exposed to above the WEL for the substance in question.

In conjunction with WELs, EU hazard and precautionary statements should also be consulted when assessing the risk of substances.

Requirement for risk assessment and review

A risk assessment must be undertaken prior to any work commencing to enable the employer to assess the risks involved and to adequately control the exposure of their employees to substances hazardous to health.

Risk assessment

A risk assessment comprises:

  • Recognition (of hazardous properties).
  • Evaluation (of risk, likelihood and severity of outcome).
  • Control (implementation of measures to achieve and maintain adequate control of risk).
  • Keeping a written or electronic record, in all but the simplest and most obvious cases.

A risk assessment will only be considered to be suitable and sufficient if the detail and expertise with which it is carried out are in accord with the nature and degree of risk arising from the work and the complexity of the work concerned.

It is not necessary to carry out a risk assessment for each separate substance used in any work activity; indeed this method may be counter productive as it does not take into account the possible reactions of chemicals as they combine to form solutions, or by-products that may be produced as a result of laboratory procedures. Thus, in a laboratory, it is the risks that may arise from the use of chemicals, as used in a particular activity that should be assessed; therefore one may be assessing a single chemical or a group of chemicals. It is permissible, under certain conditions, to group substances, assess risks and outline precautions for the group. Grouping conditions might be on the basis of chemical properties (i.e. similar hazards) or in the way that substances are used. This generic form of risk assessment will not be appropriate for activities involving substances which are extremely hazardous - individual activity based risk assessments must be formulated in such cases.

Review of risk assessment

The Regulations also require that an assessment shall be reviewed regularly and forthwith if:

  • There is reason to suspect that the assessment is no longer valid; or
  • There has been a significant change in the work to which the assessment relates, and
  • Where as a result of the review, changes in the assessment are required that those changes be made.

Purpose of risk assessment

The purpose of an assessment is to enable a valid decision to be made about measures necessary to control substances hazardous to health arising from any work. It also enables the employer to demonstrate readily, both to himself and other persons, that all the factors pertinent to the work have been considered, and that an informed and valid judgement has been reached about the risks, and the steps that need to be taken to achieve and maintain adequate control.

The COSHH Regulations provide a framework to protect people at work against health risks that may arise from work activities that expose them to hazardous substances. The essential steps that must be taken are:

  • Assess the risks to health arising from the use of the hazardous substances in the work activity.
  • Decide what precautions and control measures are necessary to minimise the risk.
  • Implement the control measures.
  • Ensure control measures are used and maintained.
  • Monitoring exposure of workers (if necessary).
  • Consider whether health surveillance is appropriate, or required
  • Ensure the operatives have sufficient information, instruction and training so as to perform the work safely and competently
  • Ensure there is in place adequate procedures to deal with emergency situations.

Risk assessment forms

The Health and Safety Department has produced a template risk assessment form in relation to COSHH. This one form replaced the two previous forms HS1 and HS2.

Detailed guidance on completion of the form is available with the template forms.

Control measures

The risk assessment should identify any control measures required to eliminate or reduce potential exposure to hazardous substances. Further information on some control measures available can be found at the following sections:


All staff and students who use or are affected by substances which are covered by the Control of Substances Hazardous to Health Regulations should undertake this e-learning course to understand the legislation governing hazardous substances, University procedures, possible risks associated with these types of substances and control measures to reduce the risks.

STAFF (course provided in People and Money)

Self-enrol on Practical CoSHH Assessment training course

STUDENTS (course currently in Learn Original - will be provided in Learn Ultra soon)

COSHH training

Biological exposure

Any exposure to biological substances hazardous to health must also be assessed and controlled. More guidance is available on the Biosafety Unit website.