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Workplace exposure limits

As an employer, you must protect workers from exposure to hazardous substances, including dust, fumes, chemicals, vapours, mists, nanotechnology, gases, biological agents and germs that cause disease.

Where substances have been classified as carcinogens, mutagens or asthmagens, to comply with the Control of Substances Hazardous to Health Regulations 2002 (COSHH)[61], exposure must be controlled to as low as is reasonably practicable (ALARP)[62].

Exposure to a substance is uptake into the body by:

  • breathing fume, dust, gas or mist
  • skin contact
  • injection into the skin
  • swallowing

Workplace exposure limits (WELs) are GB occupational exposure limits approved by HSE. They are set to help protect workers’ health. WELs are concentrations of hazardous substances in the air, averaged over a set period of time.

Find WELs in EH40

Many thousands of substances are used at work but only about 500 substances have WELs. EH40 Workplace exposure limits[63] is a publication which contains a list of all current GB WELs. The list is legally binding under COSHH.

The list is amended when new or revised WELs are approved.

Monitor WELs

You can check that exposure to hazardous substances is below their WEL by monitoring[64]. This means measuring the substance in the air that a worker breathes while they are doing a task.

You may get a consultant to monitor substances in your workplace. Exposure measurement: Air sampling G409 (PDF) [65] tells you what to expect from a competent consultant who provides monitoring services.

Monitoring can be a useful indicator to check whether the control measures you have in place are effective. If they are, exposures are likely to be below the WEL.

Go to COSHH essentials for more guidance on this[66].

How WELs are set

When Great Britain was part of the EU, HSE was involved in the EU regime for setting WELs. We are no longer part of the EU regime, we have a blended approach to controlling exposures, such as communicating what proportionate control measures we expect rather than solely introducing a WEL, as directed by evidence.

Where there is evidence to support the introduction of a new/revised WEL, HSE will follow its own approach for GB workplaces:

  • the substance will be assessed and analysed by relevant specialists, including an economic assessment
  • the Workplace Expert Health Committee (WHEC) will act as independent experts to review the scientific basis for any WEL proposed
  • there will be a public consultation on the updates
  • they will be approved by the HSE Board

HSE has considered the evidence on all outstanding EU limits and will introduce a revised limit for 3 of them. These are specific to underground mining and tunnelling and already published in EH40/2005[67], which contains all updated limits.

See also

Link URLs in this page

  1. COSHHhttps://www.hse.gov.uk/COSHH/index.htm
  2. COSHH overviewhttps://www.hse.gov.uk/COSHH/basics/index.htm
  3. What is a ‘substance hazardous to health’?https://www.hse.gov.uk/COSHH/basics/substance.htm
  4. I’m self-employed. Does this apply to me?https://www.hse.gov.uk/COSHH/basics/selfemployed.htm
  5. What you need to dohttps://www.hse.gov.uk/COSHH/basics/whatdo.htm
  6. COSHH assessmenthttps://www.hse.gov.uk/COSHH/basics/assessment.htm
  7. Substitutionhttps://www.hse.gov.uk/COSHH/basics/substitution.htm
  8. Exposure limitshttps://www.hse.gov.uk/COSHH/basics/exposurelimits.htm
  9. Chemical safety data sheetshttps://www.hse.gov.uk/COSHH/basics/datasheets.htm
  10. Control measureshttps://www.hse.gov.uk/COSHH/basics/control.htm
  11. Permits to workhttps://www.hse.gov.uk/COSHH/basics/permits.htm
  12. Personal protective equipmenthttps://www.hse.gov.uk/COSHH/basics/ppe.htm
  13. Monitoringhttps://www.hse.gov.uk/COSHH/basics/monitoring.htm
  14. Health surveillancehttps://www.hse.gov.uk/COSHH/basics/surveillance.htm
  15. Training for employeeshttps://www.hse.gov.uk/COSHH/basics/training.htm
  16. Emergencieshttps://www.hse.gov.uk/COSHH/basics/emergencies.htm
  17. Detailed overviewhttps://www.hse.gov.uk/COSHH/detail/index.htm
  18. COSHH, CLP and REACHhttps://www.hse.gov.uk/COSHH/detail/coshh-clp-reach.htm
  19. REACH and COSHHhttps://www.hse.gov.uk/COSHH/detail/reach.htm
  20. Principles of good practicehttps://www.hse.gov.uk/COSHH/detail/goodpractice.htm
  21. Overview - Your industryhttps://www.hse.gov.uk/COSHH/industry/index.htm
  22. Agriculturehttps://www.hse.gov.uk/COSHH/industry/agriculture.htm
  23. Bakinghttps://www.hse.gov.uk/COSHH/industry/baking.htm
  24. Beautyhttps://www.hse.gov.uk/COSHH/industry/beauty.htm
  25. Cateringhttps://www.hse.gov.uk/COSHH/industry/catering.htm
  26. Cleaninghttps://www.hse.gov.uk/COSHH/industry/cleaning.htm
  27. Engineeringhttps://www.hse.gov.uk/COSHH/industry/engineering.htm
  28. Fumigationhttps://www.hse.gov.uk/COSHH/industry/fumigation.htm
  29. Hairdressinghttps://www.hse.gov.uk/COSHH/industry/hairdressing.htm
  30. Offshore oil and gashttps://www.hse.gov.uk/COSHH/industry/offshore.htm
  31. Printinghttps://www.hse.gov.uk/COSHH/industry/printing.htm
  32. Motor vehicle repairhttps://www.hse.gov.uk/COSHH/industry/mvr.htm
  33. Weldinghttps://www.hse.gov.uk/COSHH/industry/welding.htm
  34. Woodworkinghttps://www.hse.gov.uk/COSHH/industry/woodworking.htm
  35. Frequently asked questionshttps://www.hse.gov.uk/COSHH/faq.htm
  36. Overview - Resourceshttps://www.hse.gov.uk/COSHH/resources.htm
  37. COSHH Essentialshttps://www.hse.gov.uk/COSHH/essentials/index.htm
  38. Overview - Case studieshttps://www.hse.gov.uk/COSHH/casestudies/index.htm
  39. Soldererhttps://www.hse.gov.uk/COSHH/casestudies/solder.htm
  40. Bakerhttps://www.hse.gov.uk/COSHH/casestudies/baker.htm
  41. Cookhttps://www.hse.gov.uk/COSHH/casestudies/cook.htm
  42. Weldershttps://www.hse.gov.uk/COSHH/casestudies/welder.htm
  43. Isocyanateshttps://www.hse.gov.uk/COSHH/casestudies/isocyanates.htm
  44. Dermatitishttps://www.hse.gov.uk/COSHH/casestudies/dermatitis.htm
  45. Overview - Example risk assessmentshttps://www.hse.gov.uk/COSHH/riskassess/index.htm
  46. Officehttps://www.hse.gov.uk/COSHH/riskassess/office.htm
  47. DIY shop https://www.hse.gov.uk/COSHH/riskassess/diyshop.htm
  48. Workshop https://www.hse.gov.uk/COSHH/riskassess/workshop.htm
  49. Engineer https://www.hse.gov.uk/COSHH/riskassess/engineer.htm
  50. Sandwich makerhttps://www.hse.gov.uk/COSHH/riskassess/sandwichmaker.htm
  51. Garden centrehttps://www.hse.gov.uk/COSHH/riskassess/gardencentre.htm
  52. Paving companyhttps://www.hse.gov.uk/COSHH/riskassess/paving.htm
  53. Feed mill https://www.hse.gov.uk/COSHH/riskassess/feedmill.htm
  54. Die caster https://www.hse.gov.uk/COSHH/riskassess/diecaster.htm
  55. Electronicshttps://www.hse.gov.uk/COSHH/riskassess/electronics.htm
  56. Fruit farmhttps://www.hse.gov.uk/COSHH/riskassess/fruitfarm.htm
  57. Warehousehttps://www.hse.gov.uk/COSHH/riskassess/warehouse.htm
  58. Further informationhttps://www.hse.gov.uk/COSHH/furtherinfo.htm
  59. Publicationshttps://www.hse.gov.uk/COSHH/publications.htm
  60. Research reportshttps://www.hse.gov.uk/COSHH/research-reports.htm
  61. Control of Substances Hazardous to Health Regulations 2002 (COSHH)https://www.hse.gov.uk/COSHH/index.htm
  62. as low as is reasonably practicable (ALARP)https://www.hse.gov.uk/enforce/expert/alarpglance.htm
  63. EH40 Workplace exposure limitshttps://www.hse.gov.uk/pubns/books/eh40.htm
  64. monitoringhttps://www.hse.gov.uk/COSHH/basics/monitoring.htm
  65. Exposure measurement: Air sampling G409https://www.hse.gov.uk/pubns/guidance/g409.pdf
  66. Go to COSHH essentials for more guidance on thishttps://www.hse.gov.uk/COSHH/essentials/direct-advice/index.htm
  67. EH40/2005https://www.hse.gov.uk/pubns/books/eh40.htm
  68. EH40/2005 Workplace exposure limitshttps://www.hse.gov.uk/pubns/books/eh40.htm
  69. Working with substances hazardous to health: A brief guide to COSHHhttps://www.hse.gov.uk/pubns/indg136.htm
  70. COSHH Essentialshttps://www.hse.gov.uk/COSHH/essentials/index.htm
  71. Case studies (Examples of real life situations with COSHH)https://www.hse.gov.uk/COSHH/casestudies/index.htm
  72. Example risk assessments (Use these to get ideas for completing assessments)https://www.hse.gov.uk/COSHH/riskassess/index.htm
  73. Nanotechnologyhttps://www.hse.gov.uk/nanotechnology/index.htm
  74. Risk assessmenthttps://www.hse.gov.uk/risk/index.htm
  75. Local exhaust ventilation micrositehttps://www.hse.gov.uk/lev/index.htm
  76. Chemicals micrositehttps://www.hse.gov.uk/chemicals/index.htm
  77. Monitoringhttps://www.hse.gov.uk/COSHH/basics/monitoring.htm

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2025-02-25