Occupational asthma

Definition

Occupational asthma is a lung disorder in which various substances found in the workplace lead to breathing difficulties.

See also:

• Asthma

Alternative Names

Asthma - occupational exposure; Irritant-induced reactive airways disease

Causes, incidence, and risk factors

Many substances in the workplace can cause occupational asthma. The most common triggers are wood dust, grain dust, animal dander, fungi, or other chemicals (especially diisocyanates).

Though the actual rate of occurrence of occupational asthma is unknown, it is suspected to cause 2 - 20% of all asthma cases in industrialized nations.

The following workers are at higher risk:

• Bakers
• Detergent manufacturers
• Drug manufacturers
• Farmers
• Grain elevator workers
• Laboratory workers
• Metal workers
• Millers
• Plastics workers
• Woodworkers

Symptoms

Symptoms are usually due to swelling of the airways and spasms of the muscles lining the airways. This reduces the amount of air that can pass through, and can lead to wheezing sounds.

Symptoms usually occur shortly after you are exposed to the offending substance, and often improve or go away when you leave work. Some people may not have symptoms until 12 or more hours after being exposed to the allergen.

Symptoms usually get worse toward the end of the work week and may (but not always) go away on weekends or vacations.

In general, symptoms include:

• Coughing
• Tight feeling in the chest
• Shortness of breath
• Wheezing

Signs and tests

The health care provider will perform a physical exam and ask questions about your medical history. Your symptoms may have a pattern of getting worse with a specific workplace environment or substance.

The health care provider may hear wheezing when listening to the chest with a stethoscope.

The following tests may be used to diagnose this condition:

• Blood tests to detect specific antibodies to the suspected substance
• Bronchial provocation test (test measuring reaction to the suspected allergen)
• Chest x-ray
• Complete blood count
• Peak expiratory flow rate
• Pulmonary function tests

Treatment

Avoiding exposure to the substance that is causing your asthma is the best treatment.

• The best option is to change jobs, but this may be difficult to do.
• Moving to a different location at the job where there is less exposure to the substance may help, but it does not seem to make a difference for many people. Over time, even a very small amount of the substance can trigger an asthma attack.
• Using a respiratory device to protect or reduce your exposure may help.

Asthma medicines (almost always inhalers) may help you manage your symptoms. Talk to your doctor about these medicines.

• Asthma quick-relief drugs help relax the muscles of your airways. They are called bronchodilators.
• Asthma control drugs are taken every day to prevent symptoms.

Support Groups

See: Asthma and allergy - support group

Expectations (prognosis)

Occupational asthma may continue to get worse if you continue to be exposed to the substance that is causing the problem, even if medicines improve your symptoms.

In some instances, symptoms may continue even when the source of exposure is removed.

In general, the outcome for people with asthma is good. However, symptoms may continue for years after workplace exposure has been eliminated.

Complications

• Negative impact on personal finances and career for people who need to change jobs
• Respiratory fatigue
• Side effects of asthma medications

Calling your health care provider

Call your health care provider if you have symptoms of asthma.

Prevention

You can reduce asthma symptoms by avoiding known allergens and airway irritants.

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References

Dykewicz MS. Occupational asthma: current concepts in pathogenesis, diagnosis, and management. J Allergy Clin Immunol. 2009;123:519-528.