2. Determine how a person can be exposed to hazardous substances

The second of the eight Principles of COSHH considers the three different ways in which a person can be exposed to hazardous substances. A COSHH Risk Assessment will determine which routes of exposure apply.

The three ‘routes of exposure’

There are three potential routes of exposure to hazardous substances:

  • Inhalation
  • Ingestion
  • Skin absorption

Use of hazardous substances in the workplace more than likely carries an element of risk to the health and safety of employees. The level of risk depends on three factors:

  • Substance usage
  • The substance’s properties – physical, biological and chemical
  • The route(s) of exposure

Identifying Routes of Exposure

Your risk assessment should identify all of the ways in which a hazardous substance could enter the body. You should make a note of how the substance could affect the skin when concerning direct contact. Finally, you need to establish which route of exposure carries the greatest level of risk in order to determine the main focus of control.

Focus for Control

You need to know what to look out for when implementing control methods to the different routes of exposure.


What should you do if you find that the main route of exposure is inhalation? You will need to focus your control efforts on the source(s) of the hazardous substance’s emission. The substance emission may be:

  • Dust
  • Fibres
  • Vapour
  • Mist
  • Gas

Skin Contact

Where the most significant exposure route is found to be skin contact (whether exposure occurs through absorption or directly impacts skin health), the main focus should be on bodily contamination.

Staff should be provided with the following in order to minimise contamination:

  • Suitable clean and accessible facilities for personal hygiene and changing
  • Clean (or disposable) work-wear if appropriate
  • Separate storage areas for work and home clothes
  • Clearly distinct ‘clean’ and ‘dirty’ areas (if there is a high risk of contamination)

Gloves are a popular form of skin protection. However, it is important to remember that it is possible for substances to be transferred from the outside to the inside of gloves. In order to mitigate this risk, workers need to be trained to safely put on and remove their gloves. If correctly adhered to, this control method represents an easy and effective way of minimising exposure. It should also be noted that it is vital to ensure your chosen gloves are appropriate for their intended purpose. Additionally, protection provided by gloves deteriorates with use and age; you need to check with the supplier or manufacturer how long they can be used before replacements are needed.

If the workspace can become contaminated, then you need to prevent staff from consuming anything, smoking or applying cosmetics in this space. Workers should have a separate area to eat, drink and relax.

You need to keep a regular schedule of cleaning and maintenance in order to maintain workplace hygiene and avoid the spread of hazardous substances. Introduce clear procedures and practices to facilitate this. You may consider using photographs as a visual aid for staff.

Ensure regular cleaning of surfaces that can become contaminated. The frequency at which this should happen depends on how often the surface becomes contaminated and how frequently skin contact is likely to take place.


Finally, if you find ingestion to be the primary route of exposure, the focus of control should be to avoid substance contact with surfaces, clothing and skin.

In Conclusion

Understanding how a person can come into contact with hazardous substances is key to creating and implementing effective control measures. Read our next blog in the series to find out more.

Our approach

Get in touch with Workplace Exposure. Either give us a call on 0800 689 4386, or fill in our enquiry form to discuss your monitoring or consultancy requirements.

We’ll then provide you with a no obligation proposal, we can often give an initial idea of fees whilst we discuss your needs.

Once you’ve accepted our proposal we can then schedule the work.

Following our site visit we’ll provide you with a comprehensive report giving you advice, recommendations and control measures where appropriate.

Implement the outcomes for compliance and a happier healthier workplace.