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Every year exposure to hazardous substances at work affects the health of thousands of people. Frequently reported illnesses are:

  • Lung disease (dusty conditions)
  • Skin irritation
  • Dermatitis or skin cancer (frequent contact with oils, contact with corrosive liquids)
  • Occupational asthma (sensitisation to isocyanates in paints or adhesives), and
  • Occupational cancer.

Employers are obligated to protect workers and others who may be exposed to hazardous substances. The high costs of ill health arise from loss of earnings, loss of productivity, prosecution and civil action amongst others.

There are many hazardous substances in use in industry today therefore it is essential to ensure first of all that those being used are absolutely necessary, and that there are no safer alternatives. Secondly it is vital that employees and the environment are protected from the effects of these substances by the use of training and appropriate protective measures. 

What is this?
This is a written procedure that tells you how to undertake COSHH assessments and identify and control hazardous substances in the workplace. A PDF of the procedure is available to download (see attached), please use it in conjunction with the attached Employee Substance Matrix and Toolbox Talk.

Substances hazardous to health can be identified in several ways:

  • A substance that has been assigned a Workplace Exposure Limit (WEL) in the HSE Guidance Note EH40: 2005 – Workplace Exposure Limits.
  • It has a black/orange label on the container which classifies it as very toxic, toxic, harmful, corrosive or irritant.
  • Biological agents such as bacteria and viruses.

Note: These procedures do not cover carcinogens or biological agents due to their complexity.

Why do we have to complete COSHH assessments?

  • To assess the risks to health from hazardous substances in your workplace;
  • To help prevent accidents and ill health arising from your work activities; and
  • Legislation requires you to carry out COSHH assessments and to record any significant findings.

How do I complete a COSHH assessment?

  1. Identify all the hazardous substances used in or created by your workplace activities and the likelihood of exposure.
  2. Obtain Material Safety Data Sheets (MSDS) as required by the Chemical Hazard (Information and Packaging) Regulations 2002 (CHIP). These come from the suppliers of the products. If you are manufacturing a product then you will have to prepare a MSDS for distribution to your employees and customers.
  3. Using the Material Safety Data Sheets identify how the substances can harm your workers.
  4. Identify what control measures are needed to protect your workforce.
  5. Ensure that control measures are used and maintained properly and that safety procedures are followed.
  6. If necessary, monitor the exposure of employees to hazardous substances.
  7. Carry out health surveillance where appropriate.
  8. Prepare plans and procedures to deal with accidents, incidents and emergencies.
  9. Provide your employees with suitable and sufficient information, instruction and training.

Assessment of substances

The person responsible for implementing this procedure must ensure that:

  • A site survey is undertaken identifying all hazardous substances on site.
  • A document is maintained outlining what substances are going to be kept.

The following information must be maintained for substances that are kept:

  • Material Safety Data Sheet.
  • The quantities, volumes and location of the substances held on site.
  • How employees may come into contact with substances (This should include potential exposure if control measures fail), and which employees will encounter which products.

How do I control exposure to hazardous substances?

Identify the appropriate control measures required to protect the health of the person exposed. The following hierarchy should be considered:

E = Elimination - Remove the substance from the workplace.
R = Replacement or Reduction - Use substances that are less hazardous or reduce the amount.
I = Isolation - Introduce engineering controls that stop the exposure at source. Deny employee access to the substance.
C = Control - Implement a safe system of work or follow industry ‘good practice’. Supply information, instruction and training.

Wherever possible, the control measures should eliminate the requirement for use of personal protective equipment (PPE).

What if the substance has a Workplace Exposure Limit (WEL)?

HSE has established WELs for a number of substances. The aim of WELs is to replace the existing Occupational Exposure Standards (OESs) and Maximum Exposure Limits (MELs), which employers often found difficult to understand and implement, with one simple system.

The intention is to contain exposure below a set limit. A WEL is the average maximum concentration of an airborne substance to which employees may be exposed.

Many substances in the workplace have exposure limits. To find out if the substance you are handling has an exposure limit then go to:

  • HSE publication: EH40:2005 - Workplace Exposure Limits

What do I need to tell my employees?

Provide information and training for the users to enable them to handle the substances safely. This can be achieved by utilising ‘COSHH information sheets’; these are available as an addition to this procedure.

If personal monitoring has been undertaken the employees need to know the results, how the exposure may affect them, and what controls need to be followed.

When should I review the assessment?

The assessment should be reviewed regularly (at least every 5 years).

The assessment should be reviewed immediately if you suspect it is no longer valid after:

  • The examination of engineering controls
  • Monitoring exposure in the workplace
  • Health surveillance or the confirmed case of occupation-induced disease

The assessment should be reviewed if there has been a significant change in the work you are doing such as:

  • A change of the substances being used
  • Plant modification, including engineering controls
  • The process or methods of work
  • The volume or rate of production

What maintenance, examination and testing do I need to undertake?

All control measures, including PPE, need to be maintained in an efficient state.

Local Exhaust Ventilation (LEV) needs thorough examination and testing by a competent person at intervals not exceeding 14 months. Note: Stricter timescales are in place for metal casting fumes. Please refer to the general COSHH ACOP. Respiratory protective equipment must be inspected at routine intervals (every 3 months is  a suggestion), dependent on the level of use.

Records of examination and test must be held for a minimum of 5 years.

Do I need to undertake exposure monitoring?

You have to measure the concentration of hazardous substances in the air breathed in by workers where your assessment concludes that:

  • There could be serious risks to health if control measures fail or deteriorate;
  • Exposure limits might be exceeded; or
  • Control measures might not be working properly.

Do I need to undertake health surveillance?

You need to carry out health surveillance in the following circumstances:

  • Where an employee is exposed to one of the substances listed in Schedule 6 of COSHH.
  • Where employees are exposed to a substance linked to a particular disease or adverse health effect, there is a reasonable likelihood of it occurring, and it is possible to detect it.

Health screening records need to be held for 40 years. If a company ceases to trade, the records should be offered to the HSE for safekeeping.


  • Control of Substances Hazardous to Health Regulations

Associated documentation

  • Hazardous substance list and employee matrix H&SCOSHH01
  • Manufacturer’s Material Safety Data Sheets
  • ‘COSHH information sheets’
  • Examination and test records
  • Personal exposure monitoring sheets

This workplace procedure forms part of a Health & Safety Risk Management System for employers in the quarrying industry. The procedures, which cover a wide range of workplace risks and hazards, can be viewed here

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