Occupational Asthma

Asthma and your occupation

Approximately 10 to 25 percent of adults with asthma experience occupational asthma. Occupational asthma is a type of asthma caused by exposure to inhaled irritants in the workplace. Occupational asthma is often a reversible condition, which means the symptoms may disappear when the irritants that caused the asthma are avoided. However, permanent damage can result if the person experiences prolonged exposure. Examples of workplace irritants include:

  • Dusts

  • Gases

  • Fumes

  • Vapors

What are the symptoms of occupational asthma?

Occupational asthma symptoms are the same as any asthma exacerbation, such as wheezing, shortness of breath, runny nose, nasal congestion, eye irritation, and chest tightness. These symptoms may get worse during exposure to the irritant(s) at work. The cause can be allergic or nonallergic in nature. Symptoms may get better when the person is not at work. Sometimes, occupational asthma symptoms do not appear until several hours after the exposure, even while at home after work. At the onset of the disease, symptoms may subside during weekends and vacations, but exposure to an occupational irritant can cause asthma within 24 hours. However, during later stages of occupational asthma, asthma symptoms may become a problem during exposure to other, more common asthma triggers, such as smoke, dust, and temperature changes.

What substances cause occupational asthma?

Although new substances are developed every day that may cause occupational asthma, some known airborne irritants in the workplace include:



Type of occupations/
environments at risk

Chemical dusts and vapors

Isocyanates, trimellitic anhydride, phthalic anhydride

Manufacturers of foam mattresses and upholstery, insulation, packaging materials, plasticizers, and polyurethane paint

Animal substances

Bacterial dusts, dander, hair, mites, protein dusts, small insects

Farmers, animal handlers, kennel workers, jockeys, and veterinarians

Organic dusts

Cereals, coffee, flour, grains, tea

Millers, bakers, and other food processors

Cotton, flax, and hemp dust

Dusts from cotton and textile industry

Cotton and textile workers


Chromium, nickel sulfate, platinum, soldering fumes

Manufacturers of metals and refineries

Man wearing a face mask while sanding a wood floor.

How can occupational asthma be prevented?

Avoidance of triggers is the best prevention against asthma. If occupational asthma symptoms do occur, you may need to change jobs to avoid exposure. However, certain steps taken in the workplace can help reduce the risk of occupational asthma:

  • Change the work process to better handle irritant exposure

  • Use industrial hygiene techniques that are appropriate for the type of irritant you are exposed to and that will keep exposure levels to a minimum

  • Have regular medical checkups to identify possible damage that may be occurring to the lungs or other medical conditions specifically related to the irritant exposure

  • Be aware of any personal and/or family medical history of asthma which may put you at greater risk for occupational asthma in certain industries

The degree to which cigarette smoking contributes to occupational asthma is not known, but smokers are more likely than nonsmokers to develop lung problems in general.

How is occupational asthma diagnosed?

Diagnosis of occupational asthma usually includes a detailed medical history and a medical examination to establish the relationship of the symptoms to exposure at work. Other diagnostic procedures may include pulmonary function tests before and after work to detect narrowing of the airways, blood and sputum lab tests, and a chest X-ray to rule out other lung diseases.

Treatment for occupational asthma

Treatment for occupational asthma usually includes avoiding the substance that triggers the asthma attack or symptoms. Persons with occupational asthma should also avoid inhaling gases, such as chlorine, or nitrogen dioxide, and sulfur dioxide, as these substances can make asthma symptoms more severe. Other treatment may include medications to control the asthma. If the occupational asthma is advanced, treatment may also include:

  • Medications

  • Physical therapy

  • Breathing aids

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