HSE update: changes to managing exposure to hazardous substances

There has been a revision of guidance from the Health and Safety Executive on acceptable limits to exposure to hazardous substances.

Full details can be read here: G409 HSE COSHH Essentials: General Guidance – Exposure Measurement: Air Sampling

Hazardous substances

Exposure to a variety of substances at work (for example chemicals, fumes, dusts and fibres) can, under some circumstances, have a harmful effect on people’s health. These are classed as “hazardous substances”. If exposure to a hazardous substance is not properly controlled, it may cause ill health through:

  • the substance being breathed in
  • being absorbed through the skin
  • being swallowed
  • acting on the body at the point of contact, i.e. the skin


The Control of Substances Hazardous to Health Regulations 2002 (COSHH) require employers to ensure that exposure is prevented, or where this is not reasonably practicable, adequately controlled.

Exposure measurement

Exposure measurement often requires carrying out a measurement survey to assess people’s exposure to hazardous substances in workplace air, and discover how and why this exposure occurs.

Acceptable Limits

Originally the HSE guidance suggested that if the results for a given task are below one third of the exposure limit, your controls are likely to be sufficient.

The HSE have now revoked and replaced this with the following guidance:
Exposure should be controlled by measures that are proportionate to the identified health risks. For asthmagens, carcinogens and mutagens, exposure should be reduced to as low a level as is reasonably practicable (ALARP). In simple terms this means the effective application of recognised good control practice, such as that identified by HSE in COSHH Essentials.

Steps to take

Employers need to demonstrate that exposure limits to hazardous substances are controlled to as low a level as is reasonably practicable.

We recommend:

  • any existing COSHH Assessments are reviewed to make sure your business is meeting these updated requirements
  • update COSHH arrangements/controls where required
  • repeat Air Monitoring assessments to demonstrate that updated controls have been successful

If you have concerns about hazardous substances in your workplace and the best way to keep your employees safe, contact us today. We can review existing COSHH Assessments and recommend updated COSHH controle, and can carry out repeat Air Monitoring.

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