Definition

Occupational asthma is a form of lung disease in which the breathing passages shrink, swell, or become inflamed or congested as a result of exposure to irritants in the workplace.

  Description

As many as 15% of all cases of asthma may be related to on-the-job exposure to:

• animal hair
• dander
• dust composed of bacteria, protein, or organic matter like cereal, grains, cotton, and flax
• fumes created by metal soldering
• insulation and packaging materials
• mites and other insects
• paints

Hundreds of different types of jobs involve exposure to substances that could trigger occupational asthma, but only a small fraction of people who do such work develop this disorder. Occupational asthma is most apt to affect workers who have personal or family histories of allergies or asthma, or who are often required to handle or breathe dust or fumes created by especially irritating material.

  Causes and symptoms

More than 240 causes of occupational asthma have been identified. Even short-term exposure to low levels of one or more irritating substances can cause a very sensitive person to develop symptoms of occupational asthma. A person who has occupational asthma has one or more symptoms, including coughing, shortness of breath, tightness in the chest, and wheezing. Symptoms may appear less than 24 hours after the person is first exposed to the irritant or develop two or three years later.

At first, symptoms appear while the person is at work or several hours after the end of the workday. Symptoms disappear or diminish when the person spends time away from the workplace and return or intensify when exposure is renewed.

As the condition becomes more advanced, symptoms sometimes occur even when the person is not in the workplace. Symptoms may also develop in response to minor sources of lung irritation.

  Diagnosis

An allergist, occupational medicine specialist, or a doctor who treats lung disease performs a thorough physical examination and takes a medical history that explores:

• the kind of work the patient has done
• the types of exposures the patient may have experienced
• what symptoms the patient has had
• when, how often, and how severely they have occurred

Performed before and after work, pulmonary function tests can show how job-related exposures affect the airway. Laboratory analysis of blood and sputum may confirm a diagnosis of workplace asthma. To pinpoint the cause more precisely, the doctor may ask the patient to inhale specific substances and monitor the body's response to them. This is called a challenge test.

  Treatment

The most effective treatment for occupational asthma is to reduce or eliminate exposure to symptom-producing substances.

Medication may be prescribed for workers who can't prevent occasional exposure. Medication, physical therapy, and breathing aids may all be needed to relieve symptoms of advanced occupational asthma involving airway damage.

A patient who has occupational asthma should learn what causes symptoms and how to control them, and what to do when an asthma attack occurs.

Because asthma symptoms and the substances that provoke them can change, a patient who has occupational asthma should be closely monitored by a family physician, allergist, or doctor who specializes in occupational medicine or lung disease.

  Prognosis

Occupational asthma is usually reversible. However, continued exposure to the symptom-producing substance can cause permanent lung damage.

In time, occupational asthma can cause asthma-like symptoms to occur when the patient is exposed to tobacco smoke, household dust, and other ordinary irritants.

Smoking aggravates symptoms of occupational asthma. Patients who eliminate workplace exposure and stop smoking are more apt to recover fully than those who change jobs but continue to smoke.

  Prevention

Industries and environments whose employees have a heightened exposure to substances known to cause occupational asthma can take measures to diminish or eliminate the amount of pollution in the atmosphere or decrease the number of workers exposed to it.

Regular medical screening of workers in these environments may enable doctors to diagnose occupational asthma before permanent lung damage takes place.

   Resources:

Organizations

• American College of Allergy, Asthma and Immunology. 85 West Algonquin Road, Suite 550, Arlington Heights, IL 60005. (847) 427-1200.

Other

• "Occupational Asthma." American Lung Association Page. 16 May 1998 http://www.lungusa.org
• "On-Job Exposure Triggers Asthma." The Detroit News 15 Dec. 1997. 16 May 1998 http://detnews.com/1997/discover/9712/16/12150021.htm