Occupational Asthma : Causes and Prevention

Occupational Asthma : Causes and Prevention

Asthma is a chronic lung disease characterized by reversible inflammation of the airways (bronchi). This inflammation, caused by the immune system, leads to narrowing of the airways, known as bronchoconstriction. Symptoms of asthma include shortness of breath, wheezing, cough, and chest tightness.

Occupational asthma is a type of asthma that is caused by exposure to a particular substance in the workplace. Previously diagnosed asthma that worsens at work is known as work-aggravated asthma.

Occupational asthma is asthma caused by, or worsened by, exposure to substances in the workplace. These substances may cause asthma in one of 3 ways:

An allergic reaction (like people with allergies who develop allergic asthma)

An irritant reaction (like a person that reacts to smoking with asthma)

A reaction which results in the buildup of naturally occurring chemicals such as histamines in the lungs resulting in an asthma attack

Examples of occupational asthma — also called work-related asthma — include:

Health care workers who develop an allergy to latex gloves by breathing in the powdered proteins from the inner lining of the gloves

Workers in the chemical industry who are exposed to substances like ammonia and develop symptoms of asthma as the result of an irritant effects, not an allergic reaction


Occupational asthma symptoms are similar to those caused by other types of asthma. Signs and symptoms may include:

-Wheezing, sometimes just at night
-Shortness of breath
-Chest tightness

Other possible accompanying signs and symptoms may include:

-Runny nose
-Nasal congestion
-Eye irritation and tearing

Occupational asthma symptoms depend on the substance you’re exposed to, how long and how often you’re exposed, and other factors. Your symptoms may:

-Get worse as the workweek progresses, go away during weekends and vacations, and recur when you return to work.
-Occur both at work and away from work.
-Start as soon as you’re exposed to an asthma-inducing substance at work or only after a period of regular exposure to the substance.
-Continue after exposure is stopped. The longer you’re exposed to the asthma-causing substance, the more likely you’ll have long-lasting or permanent asthma symptoms.


More than 250 workplace substances have been identified as possible causes of occupational asthma. These substances include:

Animal substances, such as proteins found in dander, hair, scales, fur, saliva and body wastes.

Chemicals used to make paints, varnishes, adhesives, laminates and soldering resin. Other examples include chemicals used to make insulation, packaging materials, and foam mattresses and upholstery.

Enzymes used in detergents and flour conditioners.

Metals, particularly platinum, chromium and nickel sulfate.

Plant substances, including proteins found in natural rubber latex, flour, cereals, cotton, flax, hemp, rye, wheat and papain — a digestive enzyme derived from papaya.

Respiratory irritants, such as chlorine gas, sulfur dioxide and smoke.

Asthma symptoms start when your lungs become irritated (inflamed). Inflammation causes several reactions that restrict the airways, making breathing difficult. With occupational asthma, lung inflammation may be triggered by an allergic response to a substance, which usually develops over time. Alternatively, inhaling fumes from a lung irritant, such as chlorine, can trigger immediate asthma symptoms in the absence of allergy.


The diagnosis of Occupational asthma should be considered in all working-age individuals with new-onset asthma or worsening asthma. A detailed history of occupational and potential occupational exposures is just as important as identifying environmental triggers when evaluating an asthmatic patient. Although many patients will themselves relate their symptoms to the workplace, many other cases of Occupational asthma are recognized only because the physician performed a detailed environmental history. Common screening questions include the following: What are your workplace exposures? When during the work shift or workweek do symptoms develop? Do symptoms improve during the weekend and over vacations? Do other workers have similar symptoms? The history can be supplemented with material safety data sheets from the workplace and can be compared with agents known to cause Occupational asthma. A worksite visit by the physician or by an occupational hygienist might also provide helpful information.

Although taking a good occupational history is important in establishing a link between symptoms and potential workplace exposures, a history by itself is inadequate to make the diagnosis of Occupational asthma.


The best way to prevent occupational asthma is for workplaces to control the workers’ level of exposure to chemicals and other substances that may be sensitizers or irritants. Such measures can include implementing better control methods to prevent exposures, using less harmful substances and providing personal protective equipment (PPE) for workers.

Although you may rely on medications to relieve symptoms and control inflammation associated with occupational asthma, you can do several things on your own to maintain overall health and lessen the possibility of attacks:

If you smoke, quit. In addition to all its other health benefits, being smoke-free may help prevent or lessen symptoms of occupational asthma.

Get a flu vaccination. This can help prevent illness.

Avoid nonsteroidal anti-inflammatory drugs (NSAIDS) and other medications that may make symptoms worse.

Lose weight. For people who are obese, losing weight can help improve symptoms and lung function.