Knowledge Centre


Exposure to Sensitisers & Occupational Asthma


As part of our workplace exposure testing and assessment service for clients, we often come across a frequent misunderstanding of what substances are sensitisers and the role that they play in Occupational Asthma.

If your business involves manufacturing, fabrication, welding or is based in a factory or warehouse, its very important you understand what Occupational Asthma is and how it is caused. It is now officially the most common work-related lung disease in the UK.

The following information will give you an insight into what Occupational Asthma is, how as an employer you can comply with the Health and Safety Executive (HSE) regulations and protect your workforce from this debilitating workplace disease. 

Substances that can cause Occupational Asthma (also known as asthmagens and respiratory sensitisers) can induce a state of specific airway hyper- responsiveness via an immunological, irritant or other mechanism. Once the airways have become hyper-responsive, further exposure to the substance, sometimes even to tiny quantities, may cause respiratory symptoms.

These symptoms can range in severity from simply a runny nose, to Asthma attacks where the airways of the lungs swell and narrow. This leads to attacks of wheezing, shortness of breath, chest tightness, and coughing.

Not all workers who are exposed to a sensitiser will become hyper-responsive, it is impossible to identify in advance those who are likely to become hyper-responsive. Some of the more common workplace sensitisers are as follows:

  • Soft and hard woods 

  • Flour dust (bakeries and food production)

  • Azodicarbonamide (blowing agent, used heavily in plastics industry)

  • Platinum compounds (used in catalytic convertors and chemical industry)

  • Isocyanates (associated with paint spraying activities)

  • Grain dust (fungal spores)

  • Solder fumes

  • Metal working fluids

  • Latex

  • Stainless steel welding fumes

Organisations are responsible for making an assessment of the likely exposure levels of these types of substances (COSHH reg 6) with an aim to prevent or reduce exposure to levels as low as reasonably practicable (COSHH reg 7). Activities giving rise to short-term peak concentrations should receive attention when risk management is being considered.

Health surveillance is appropriate for all employees exposed to sensitisers or liable to be exposed to a substance which may cause Occupational Asthma All employees of this type are required by health and safety law to undergo a health surveillance regime which involves an initial baseline, 6 weeks, 12 weeks and then annual surveillance plan.

If Occupational Asthma is not correctly diagnosed early, and your employees aren't protected or removed from the exposure, it can cause permanent changes to their lungs and as the business owner or health and safety manger you could be held accountable.

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