Asthma - occupational exposure

Definition

Occupational asthma is a lung disorder characterized by attacks of breathing difficulty, wheezing, prolonged exhalation, and cough. It is caused by various agents found in the work place (see also bronchial asthma). These symptoms are usually due to spasms of the muscles lining the airways, which cause them to narrow excessively.

Alternative Names

Asthma - occupational exposure; Irritant-induced reactive airways disease

Causes

There are many agents in the workplace that can cause occupational asthma. Most commonly, these include protein molecules (wood dust, grain dust, animal dander, fungi) or other chemicals (especially di-isocyanates).

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

The following workers are at higher risk:

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

Symptoms

Symptoms usually occur shortly after exposure to the offending agent (the allergen) and often improve or disappear when the affected person leaves the workplace. The symptoms often worsen as the work week progresses and resolve on weekends or vacations. Some people may experience a delayed onset of symptoms, occurring as many as 12 hours after exposure to the allergen.

Shortness of breath
Wheezing
Cough
A feeling of tightness in the chest

Exams and Tests

The medical history reveals a pattern of worsening symptoms associated with exposure to a specific agent or workplace environment. Making the association with the correct allergen can be very difficult.

Wheezing may be heard when listening to the chest with a stethoscope (auscultation).

Tests used in the diagnosis of occupational asthma may include the following:

Pulmonary function tests
Measurement of the peak expiratory flow rate (peak-flow) before and after work
Chest X-ray
CBC
Bronchial provocation test (test measuring reaction to the suspected allergen)
Blood tests to reveal specific antibodies to suspected offending substances

Treatment

The objective of treatment is to limit exposure to the allergen and improve symptoms with bronchodilator therapy. In some instances, symptoms may persist despite removal of the source of exposure. Medications include hand-held inhalers or nebulizers to deliver bronchodilators. Other therapies forbronchial asthma may be added in more severe cases.

Support Groups

Thestress related to illness can often be helped by joining a support group where members share common experiences and problems. See asthma and allergy - support group.

Outlook (Prognosis)

The outcome for people withasthma in general is good, but symptoms may persist for years after workplace exposure has been eliminated.

Possible Complications

Complications include continued asthma symptoms after removal from the source of exposure.

When to Contact a Medical Professional

Call your health care provider if signs of occupational asthma develop.

Call your health care provider if you have occupational asthma and signs of respiratory infection, or if other new symptoms, develop.

Prevention

Once the cause is determined, avoid further exposure to it.