The Control of Substances Hazardous to Health Regulations 2002 (COSHH) applies to a wide range of substances and preparations that have the potential to cause harm to humans. Mike Sopp explains the steps employers must make in order to ensure risk assessments are carried out by competent persons.


Under the regulations, employers must not proceed with any work which can expose any of their employees to any substance hazardous to health until “a suitable and sufficient assessment of the risks to employees’ health created by that work has been carried out”.

In meeting this requirement, the employer must ensure that the assessment is undertaken by a competent person. In doing, so employers must give consideration to what these competency requirements are and how they can be met.

COSHH assessments

There are many substances and preparations that have the potential to cause harm to humans, for example, through ingestion, inhalation or absorption.

Health and Safety Executive guidance states that the purpose of the risk assessment under regulation 6 of COSHH is “to enable employers to make valid decisions about the measures needed to prevent or adequately control the exposure of their employees to substances hazardous to health arising from the work”.

Under COSHH, the risk assessment must be “suitable and sufficient” and, according to guidance in the Approved Code of Practice (ACOP), “should take into account the properties of the hazardous substance or biological agent, how and when they can give rise to risks to health, and the degree to which those risks need to be taken into account”.

The ACOP also provides details as to what factors need to be given consideration in order to meet the “suitable and sufficient” criteria, including:

  • the work activity in terms of all the substances used, produced, etc.

  • the hazards in terms of the substances’ properties (physical, chemical, biological) and the form in which they are present (such as mist, gas or vapour)

  • the ways in which people may be exposed and any persons especially at risk

  • the type and extent of exposure, along with potential health effects

  • the control measures that may be required to eliminate or control exposure.

The ACOP also emphasises the need to take into consideration how the materials may be present on work premises. This may be, for instance, because they are brought into the workplace for use, emerge as a by-product of a work activity (such as waste products) or used for maintenance or repair work.

Competency requirements

The Approved Code to Regulation 6 states that “employers must ensure that whoever carries out the assessment and provides information on the prevention and control measures is competent to do so.”

This requirement arises from regulation 12 of COSHH, which requires the employer to ensure that any person (whether or not a direct employee) who carries out work in connection with the employer’s duties under COSHH has suitable and sufficient information, instruction and training. Such work will include the completion of a suitable and sufficient COSHH risk assessment.

Again, the ACOP clarifies the requirement of regulation 12 by stating that “the employer must ensure that the person, or people, to whom any work is delegated, is competent to do it” and that people carrying out the work required under regulations 6 of COSHH “should have adequate knowledge, training and expertise” in assessing risks.

To be competent, the person nominated to carry out the assessment should:

  • know how the work activity uses, produces or creates substances hazardous to health

  • have the knowledge, skills, training and experience to make sound decisions about the level of risk and the measures needed for prevention or adequate control of exposure

  • have the ability and the authority of the employer to collate all the necessary, relevant information.

It is preferable that such competency be accessible in-house, as this is commensurate with the requirements of Regulation 7 of the Management of Health & Safety at Work Regulations 1999 (MHSWR) Regulations. Therefore, wherever practicable, suitable employees should be given appropriate information, instruction and training to gain the knowledge and expertise that will give them the competence to help their employers comply with COSHH requirements in terms of risk assessing.

COSHH guidance also recognises that, on occasions, additional external competency may be required. If this becomes necessary, the employer will still need to ensure that the people involved received sufficient information about the particular circumstances of the work, including the hazardous substances used or produced and its hazardous properties.

Meeting the competency criteria

The Health and Safety Executive does not define or approve any standards of competence for the completion of COSHH risk assessments.

It is, therefore, the responsibility of the employer to identify the relevant competency required to undertake the COSHH risk assessments. Determining the levels of competency is essentially about identifying the skills and knowledge needed to complete the assessment in the specific environment in which it will be encountered, which can be influenced by the following.

  • The type(s) of hazardous substances used or produced, work activities involved and exposure characteristics.

  • The need for compliance with legislative requirements.

  • Guidance on competency in the ACOP to the COSHH Regulations.

  • The complexity of any control measures, operating procedures and instructions required to control risks.

The Institution of Occupational Health and Safety (IOSH) guidance document Setting Standards in Health and Safety provides further useful information on setting competency levels.

After the initial analysis of competency levels, it is necessary to have arrangements in place to identify and remedy any shortfalls in the current level of competency possessed by employees nominated to complete COSHH risk assessments.

This could include the undertaking of a “training needs analysis” which involves gathering of data to find out where there are gaps in the existing skills, knowledge and attitudes of employees.

Employers need to decide what data will be required to determine the above and how this can be collected. Some possible sources of data include:

  • interviews with staff to gather information on current understanding of factors to be considered in the assessment process

  • material safety data sheets and other information from suppliers of hazardous substances

  • generic risk assessments about work activities involving substances that may be potentially harmful

  • trade association best practice guidance.

Choosing the correct form of training is pivotal to the overall success of any training initiative, as the selection of an inappropriate delivery method for the new knowledge or skill will negate other important aspects such as the content and how the results of the training are to be evaluated.

Referring again to the ACOP for COSHH, this notes that employers “should consider the various ways of providing information, instruction and training and select those most appropriate to their own circumstances” and that “training should include elements of theory, as well as practice”.

Certainly, there are many commercial organisations that offer training in COSHH risk assessing, however, it may be the case that formal qualifications will be combined with more local instruction and information.

IOSH note that learning needs to be transferred and applied to the workplace. As such, some form of evaluation will be required of the information, instruction and training undertaken to ensure the necessary competency levels have been met.

This could include an internal periodic selective review of COSHH risk assessments completed by another competent COSHH risk assessor or an external review by a consultant as part of an audit process.

The ACOP also notes that training is not a one-off exercise and should be “reviewed and updated whenever significant changes are made to the type of work carried out or to the work methods used”.

Further information

  • L5: Control of Substances Hazardous to Health — Approved Code of Practice and Guidance. 2013, Health and Safety Executive

  • Chartered Institute of Personnel and Development:

  • Institution of Occupational Safety and Health — Setting standards in health and safety:

  • INDG 345: Health and Safety Training 2012, Health and Safety Executive

Last reviewed 23 April 2015