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Occupational Asthma

How a Person's Job Results in Occupational Asthma


Updated April 14, 2009

What is occupational (work-related) asthma?

Asthma is a chronic disease characterized by inflammation and smooth muscle contraction around the airways of the lungs, causing symptoms such as shortness of breath, chest tightness, wheezing and coughing. Asthma can be caused or worsened by environmental triggers, such as allergens and irritants, especially if a person’s job results in a significant amount of exposure to these triggers. Work-related asthma refers to asthma that is worsened by exposure to inhaled triggers at work, and is estimated to occur in about 1 in 4 people with asthma. Asthma that was caused by work exposures (and did not exist before the exposures) is termed occupational asthma; pre-existing asthma that is worsened by work exposures is termed work-exacerbated asthma.

What are the symptoms of work-related asthma?

The symptoms of work-related asthma are identical to symptoms of asthma from other causes. The relationship of these symptoms, however, is directly related to work exposures. People with work-related asthma may notice that their symptoms are absent or mild when away from work, such as on the weekends, holidays or vacations. Symptoms may re-appear on Monday (assuming this is the first day the person returns to work) and worsen over the course of the workweek.

What types of exposures cause work-related asthma?

A variety of triggers that cause work-related asthma. Allergic causes for work-related asthma often occur after a period when the person has no asthma symptoms, called a latency period. During this latency period, allergic antibodies are being produced, and symptoms of allergic rhinitis and/or allergic conjunctivitis may occur as a result of being exposed to the allergic trigger. Non-allergic triggers cause work-related asthma through irritant effects; there is no latency period with these non-allergic triggers.

Common jobs that lead to exposures to allergic and non-allergic triggers that may cause work-related asthma include:

  • Bakers
  • Veterinary clinic personnel
  • Laboratory personnel
  • Seafood restaurant workers
  • Healthcare workers
  • Greenhouse workers
  • Hotel housekeepers
  • Landscapers/gardeners
  • Sawmill/Lumber workers
  • Factory workers exposed to metals, epoxies and other chemicals

How is the diagnosis of work-related asthma made?

History. Knowing for sure that work exposures worsen or cause asthma may be difficult to prove. Often, a person has a suspicion that this is the case. If the following four statements are true, work-related asthma may be present:
  • Changes to exposures at work occurred just prior to the onset or worsening of symptoms
  • Unusual exposures occurred within 24 hours prior to the onset or worsening of symptoms
  • Asthma symptoms are less severe on weekends, holidays or vacation
  • There are also symptoms of allergic rhinitis (hay fever) and allergic conjunctivitis (eye allergies) at work.

Testing. Showing that a person actually has asthma is, of course, crucial to the diagnosis of work-related asthma, but it doesn’t prove that triggers at work are related to the asthma. Therefore, lung function testing while a person is at work can detect drops in lung function that may suggest the diagnosis of work-related asthma. This is most often performed using peak expiratory flow rates (PEFR), using a peak flow meter. To be correctly done, PEFRs are measures at least four times a day for four weeks to pick up changes in lung function caused by work triggers, including one week off of work to show that these changes don’t occur away from work.

Inhalation challenges, performed by having a person breathe the trigger in question while following lung function by spirometry, are potentially dangerous and are only performed by specialized research centers.

Some causes of work-related asthma are allergic in nature, and allergy testing can be performed to some of these triggers. Most often, this type of testing may rule out work-related asthma, but may not be able to absolutely make the diagnosis, either. If a person is not allergic to certain triggers for example, such as animal proteins in a person who works in a veterinarian clinic, then the person could not be diagnosed with work-related asthma. But, just because the person has allergic antibodies to certain animal proteins would not make a firm diagnosis of work-related asthma, either.

How is work-related asthma treated?

The treatment of asthma from work-related triggers is exactly the same as for asthma not caused by occupational exposures. However, complete avoidance of the environmental trigger is recommended, if possible, because people with work-related asthma who are removed from their occupational environment do better than people who remain in their jobs. If a person wishes to remain in his job despite his occupational triggers worsensing his asthma, all attempts should be made to reduce/minimize/eliminate exposures. This includes using protective equipment such as masks and/or respirators designed for such as purpose.

Learn more about the management of asthma.


Dykewicz MS. Occupational Asthma: Current Concepts in Pathogenesis, Diagnosis and Management. J Allergy Clin Immunol. 2009;123:519-28.

DISCLAIMER: The information contained in this site is for educational purposes only, and should not be used as a substitute for personal care by a licensed physician. Please see your physician for diagnosis and treatment of any concerning symptoms or medical condition.

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