Occupational asthma

Occupational asthma

Asthma Centre

Occupational asthma

There are more than 300 workplace substances that may cause occupational asthma. What are the culprits and how can this condition be managed?

How does occupational asthma (OA) develop?

OA is a form of work-related asthma that usually begins in adulthood and is triggered by breathing in or coming into contact with certain workplace substances that irritate the lungs, causing them to become inflamed. This makes breathing difficult because the muscles around the swollen, inflamed airways respond by tightening and, together with the excess mucus now being produced, restricting the normal flow of air to and from the lungs.

Two types of OA have been identified:

  1. OA caused by workplace sensitizers, for example when your body builds up an allergic reaction after being exposed to a specific substance over a long period of time (months or years). This reaction activates your immune system into producing antibodies (soldiers) that in turn trigger the release of chemicals such as histamine to fight the intruder. Unfortunately, histamine is known to cause inflammation in the lungs with all its negative consequences.
  2. OA caused by irritants, for example when a single or multiple high-level exposure to a specific substance causes an immediate reaction with asthma-like symptoms that last for a long time. This condition is also referred to as reactive airways dysfunction syndrome (RADS) or irritant induced asthma.

When to suspect OA

Although OA symptoms include the typical asthma symptoms, certain other circumstances, when present, are indicative of this condition:

  • Asthma symptoms that first appear in adulthood
  • Asthma symptoms that start after working in a specific place or being exposed to certain workplace substances
  • Asthma symptoms that are worse during the week, subside or go away during the weekend or when you are on vacation and start up again as soon as you return to work
  • Asthma symptoms that start up out of the blue after months or years of being exposed to a certain workplace substance
  • Asthma symptoms that continue even after you are no longer exposed to this substance or have stopped working at a specific place.

High-risk occupations and workplace substances

You can develop OA in just about any workplace, but the following occupations have been noted as high risk jobs that entail exposure to or handling of asthma-producing substances:

  • Any job that entails working with the chemicals used to make paints, varnishes, adhesives, laminates and soldering resin, insulation, packaging materials, etc.
  • Plastics, foam industry and upholstery workers
  • Carpenters and forest workers who are exposed to wood dust
  • Any job where respiratory irritants such as smoke, chlorine gas and sulphur dioxide are present
  • Animal handlers who are exposed to animal dander, saliva or body waste
  • Bakers and millers that are exposed to plant substances and proteins found in flour, cereals, rye, wheat and papain (derived from papaya)
  • Textile workers and jobs where cotton, flax and hemp are processed and dyed
  • Metal workers who are exposed to platinum, chromium and nickel sulphate
  • Hairdressers
  • Seafood processors
  • Health care and pharmaceutical workers.

Treating OA

Standard asthma treatment involves the use of both long-term control medications such as inhaled corticosteroids, long-acting beta agonists, combinations of the two and other oral medications and quick relief medications such as short-acting beta agonists and oral and intravenous corticosteroids. An added treatment option is allergy treatment with medicines, oral and nasal sprays, antihistamines, decongestants and immunotherapy. Immunotherapy entails injections to reduce the immune system’s reaction to asthma and allergy-causing substances in the workplace.

Unfortunately OA may negatively impact both your health and your career. Avoiding exposure to the workplace irritants or substances that trigger OA is the best line of defence along with compliance to the treatment plan outlined by your doctor. If in doubt or if you feel a bit overwhelmed, do consider joining an asthma support group where you can speak to others who are in the same situation and may already have solutions to some of the problems you may be experiencing now.


Chan-Yeung, M. et al. 2013. Occupational asthma: definition, epidemiology, causes, and risk factors. Retrieved from:  http://www.uptodate.com/contents/occupational-asthma-definitions-epidemiology-causes-and-risk-factors
Occupational asthma. 2011. Retrieved from: http://ww.mayoclinic.com/health/occupational-asthma

(Revised by M van Deventer)