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Symptoms and Signs of Occupational Asthma

Doctor's Notes on Occupational Asthma

Asthma is a chronic (ongoing, long-term) inflammation of the breathing passages of the lungs that irritates the airways, causing breathing problems. The inflammatory reaction in asthma is triggered by external factors or specific situations and exposure to a trigger worsens inflammation and results in asthma symptoms. Occupational asthma is caused by exposure to a trigger in the workplace. Common triggers include contaminants in the air, such as smoke, chemicals, vapors (gases), fumes, dust, or other particles; respiratory infections, such as colds and flu (viruses); allergens in the air, such as molds, animal dander, and pollen; temperature or humidity extremes; and emotional excitement or stress.

Symptoms for people with occupational asthma occur a short time after beginning work and subside after leaving work. For some people, symptoms worsen gradually during the workweek, go away over the weekend, and return when the new work week starts. Symptoms of occupational asthma include coughing, wheezing, chest tightness, chest pain, prolonged shortness of breath, and extreme fatigue. Allergy symptoms that occur at work but improve away from work may be a sign there are irritants in the air that could provoke asthma symptoms. Allergic symptoms include itchy, burning, or watery eyes; itchy or stuffy nose, sneezing; or itchy, red, or irritated skin.

Medical Author: John P. Cunha, DO, FACOEP
Medically Reviewed on 3/22/2019

Occupational Asthma Symptoms

In most people with occupational asthma, the symptoms appear a short time after beginning work and subside after leaving work.

  • Many have no symptoms or milder symptoms on days they do not work. The symptoms return when they return to work.
  • In some, the symptoms worsen gradually over the work week, go away over the weekend, and return when the new work week starts.
  • In others, the symptoms are slow to develop and may not be noticed until after leaving work for the day. This pattern makes it difficult to recognize a workplace trigger.
  • In the later stages of the disease, after long-term regular exposure, symptoms may not go away after you leave the workplace.

These are the most common symptoms of occupational asthma. Most people do not have all these symptoms.

Allergy symptoms that occur at work but get better away from work also may be a sign of irritants in the air that could provoke asthma symptoms. The following symptoms could occur:

  • Eyes: itchy, burning, or watery
  • Nose: itchy or stuffy, sneezing
  • Skin: itchy, red, or irritated

Occupational Asthma Causes

Asthma has two components: the underlying chronic inflammation and the periodic attacks. We do not know for certain what causes the underlying inflammation. What we do know is that the tendency to have asthma runs in families and that some people are born with the tendency.

We do know what causes asthma attacks: exposure to a trigger. The attack is similar in many ways to an allergic reaction.

  • An allergic reaction is a response by the body's immune system to an "invader." That invader can be a substance or anything that the body senses as "different."
  • When the cells of the immune system sense an invader, they set off a series of reactions that help fight off the invader.
  • It is this series of reactions that causes the production of mucus and bronchospasms. These responses cause the symptoms of an asthma attack.

In occupational asthma, the trigger is a substance or condition in the workplace that causes asthma symptoms. Most of these substances and conditions are very common and are not normally considered hazardous. Although these substances and conditions can be encountered in almost any workplace, occupational asthma is most common in workers in the following industries and jobs:

  • Plastics industry
  • Rubber industry
  • Chemical industry
  • Textile industry
  • Electronics industry
  • Painting
  • Printing
  • Dyeing
  • Metalworking
  • Welding
  • Oil refining
  • Cleaning
  • Baking and food processing
  • Farming
  • Gardening, landscaping, and horticulture
  • Working with animals
  • Laboratory work

Triggers that are often associated with a delay in the onset of symptoms (latency period) come in two groups (characterized by the size of the molecules involved). These are either high molecular weight or low molecular weight agents.

The high molecular weight agents tend to be proteins, and polysaccharides. Examples of these agents include a variety of enzymes (used in the baking and food industry), cereals (also seen in the baking industries), animal waste and shellfish (found in laboratory technicians, farmers, food processors), and latex (found in health-care workers).

Low molecular agents often have a shorter onset of symptoms and usually do not include nasal and eye irritation. Some examples of these agents include anhydrides (often used in plastics, dyes, and epoxy), metals (used in refineries, electroplating, welding), diisocyanates (found in plastics, spray paints, foundries), specific wood dusts like red cedar (found in wood carvers, furniture makers, sawmill workers), and cleaning agents (found in maintenance workers health-care professionals).

Not everyone exposed to these conditions will develop asthma. Some people are more susceptible to asthma than others. Also, exposure to some of these substances can produce chronic lung diseases other than asthma. Risk factors for occupational asthma include the following:

If asthma is not treated, the airways gradually develop a pattern of overreacting, hence, the alternative term for asthma, reactive airways disease. Common, everyday conditions, such as cigarette smoke or cold air, may cause asthma symptoms. In fact, it is part of the normal human condition for a small degree of bronchospasm to occur when the airways are exposed to cold or dry air. Normally, the body's upper airway warms and moistens the air to prevent this from occurring.

What is Asthma? Asthma Myths Debunked Slideshow

What is Asthma? Asthma Myths Debunked Slideshow

These are some of the many faces of asthma. Most researchers believe that the different patterns of asthma are all related to one condition. Other researchers feel that separate lung conditions exist. There is currently no cure for asthma, and no single exact cause has been identified. Therefore, understanding the changes that occur in asthma, how it makes you feel, and how it can behave over time is vital. This knowledge empowers you to take an active role in your own health care. Test your "asthma IQ" by taking the following true or false quiz:


Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.