Merck Manual

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Work-Related Asthma

(Occupational Asthma)


Carrie A. Redlich

, MD, MPH, Yale Occupational and Environmental Medicine Program Yale School of Medicine;

Efia S. James

, MD, MPH, Yale School of Medicine;

Brian Linde

, MD, MPH, Yale Occ and Env Medicine Program

Reviewed/Revised Nov 2023
Topic Resources

Work-related asthma is a reversible narrowing of the airways caused by inhaling particles or vapors in the workplace, which act as irritants or cause an allergic reaction.

  • Work-related asthma may cause shortness of breath, tightness in the chest, wheezing, and coughing.

  • The key to diagnosis is a careful occupational and environmental exposure history.

  • Treatment involves avoiding the trigger and, when that is not possible, using medications to open the airways and reduce inflammation.

Approximately 15 percent of adult-onset asthma is attributed to occupational exposure. Work-related asthma should be suspected in all adults with asthma, especially those with new-onset or worsening asthma.

Workplace-related asthma can continue to cause symptoms even after exposure to the irritant or allergen has stopped.

Work-related asthma can take various forms:

  • Sensitizer-induced occupational asthma

  • Irritant exposure and reactive airways dysfunction syndrome (RADS)

  • Work-exacerbated asthma

Sensitizer-induced occupational asthma

Sensitizer-induced occupational asthma develops following an immune response Overview of the Immune System The immune system is designed to defend the body against foreign or dangerous invaders. Such invaders include Microorganisms (commonly called germs, such as bacteria, viruses, and fungi) Parasites... read more to an allergen encountered in the workplace. Examples of allergens include grain dusts, latex, chemicals, metals, animal dander, and wood dusts. Hundreds of workplace substances can be allergens and cause asthma. Risk of developing sensitizer-induced asthma varies by occupation and the specific substances encountered in the workplace.

Irritant exposure and reactive airways dysfunction syndrome

Irritant-induced asthma refers to asthma that occurs following exposure to respiratory irritants at work. Irritants can cause cell damage and inflammation. A high level of exposure to an irritant, such as in a workplace accident or chemical spill, can result in reactive airways dysfunction syndrome Reactive airways dysfunction syndrome Asthma is a condition in which the airways narrow—usually reversibly—in response to certain stimuli. Coughing, wheezing, and shortness of breath that occur in response to specific triggers are... read more Reactive airways dysfunction syndrome (RADS). RADS refers to the new onset of asthma symptoms within 24 hours of a high-level exposure to a known irritant.

In addition to RADS, irritant-induced asthma also includes development of asthma in workers with chronic exposure to moderate levels of irritants. Asthma can also be triggered by recurrent low-level exposure to irritants, such as cleaning products and disinfectants.

Work-exacerbated asthma

Work-exacerbated asthma is pre-existing asthma that is worsened by asthma triggers at work. Multiple exposures can exacerbate (worsen) asthma including temperature extremes, humid and damp environments, dust, cleaning products, and a wide range of irritants and allergens that are common in the environment.


Symptoms of Work-Related Asthma

Symptoms of work-related asthma caused by sensitization to a substance in the workplace typically develop over weeks to years. Once sensitized to a particular substance, the worker can respond to very low concentrations of that substance, making exposure control challenging.

Typical symptoms include shortness of breath, chest tightness, wheezing, and cough. Sometimes people show signs of allergy at work, with symptoms of sneezing, runny nose, and watery eyes. These allergy symptoms may be present for months or years before shortness of breath and other breathing symptoms develop.

Symptoms typically develop and/or worsen at work and improve when the person is away from work (for example, on weekends and holidays). Continued exposure at work causes the symptoms to become more chronic and persistent, and the association with work can become less apparent.

Diagnosis of Work-Related Asthma

  • History of asthma symptoms at work

To make a diagnosis of work-related asthma, doctors ask about the symptoms and about exposure to any substances known to cause asthma.

Doctors consider work-related asthma in adults with new-onset or worsening asthma. Improvement in asthma symptoms when the person is away from work (for example, on weekends or holidays) raises doctors' suspicion of work-related asthma.

Following clarification of the asthma diagnosis, doctors document the timing, onset, and progression of asthma in relationship to work and also non-workplace exposures to asthma triggers. They obtain a thorough occupational history, including job title, industry, job tasks, and description of the work environment and materials used. Doctors should ask about specific processes, locations, or exposures at work that are associated with worsening symptoms.

Safety data sheets, mandatory at all work sites in the United States, can be used to identify irritants and allergens that can cause asthma. However, the absence of a known irritant on the safety data sheet does not exclude the diagnosis of work-related asthma. For the few asthma-causing substances for which commercially available allergy testing is available, such as for certain animals and grains, allergy testing can help identify a causative substance.

People may use a device to monitor their airways while at work and away from work. This device, called a portable peak flow meter, measures the rate at which a person can blow air out of the lungs. When rates are slower at work than at home, this suggests work-related asthma.

Work-exacerbated asthma

Doctors base the diagnosis of work-exacerbated asthma on the person's history of pre-existing asthma (symptoms, medical history, medication usage, variable airflow obstruction) and the presence of conditions at work that can exacerbate (worsen) asthma. Worsening asthma related to work can be documented by noting worsening symptoms, increased frequency of doctor visits for asthma symptoms, increased use of asthma medications, or rarely, worsening lung function related to work. Recurrence of asthma that had resolved may be new-onset work-related asthma.

Treatment of Work-Related Asthma

  • Eliminating or reducing exposure

  • Medications to open airways

  • Workplace modification or change

In addition to reducing or eliminating exposures at work, medical treatments are the same as for other types of asthma Drugs for Preventing and Treating Asthma Drugs allow most people with asthma to lead relatively normal lives. Most of the drugs used to treat an asthma attack can be used (often in lower doses) to prevent attacks. (See also Asthma... read more Drugs for Preventing and Treating Asthma . Medications that open the airways (bronchodilators) may be given, preferably in an inhaler (for example, albuterol). Medications that reduce inflammation may be given, either in an inhaler (for example, the corticosteroid triamcinolone) or as a tablet (for example, montelukast). For severe attacks, corticosteroids such as prednisone may be taken by mouth for a short time. For long-term management, inhaled corticosteroids are preferred to oral corticosteroids. Increases of asthma medications or their doses should raise concern for ongoing, triggering exposures at work.

With sensitizer-induced occupational asthma, people can react to extremely low levels of airborne exposure once they have been sensitized to a substance. Thus, the recommended management consists of identification of and complete removal from further exposure to the sensitizing substance. Given that complete removal from the workplace can involve substantial socioeconomic consequences, transfer to a different work area at the same workplace or improving engineering controls (by controlling the environment) is sometimes tried. In situations with potential for ongoing exposure to the sensitizing substance, close monitoring for worsening asthma is essential, including symptoms, medication usage, and lung function. Early recognition and prompt removal from the sensitizing substance result in better outcomes, but asthma commonly persists even when the person is away from the substance.

People with irritant-induced occupational asthma and work-exacerbated asthma may be able to continue their current jobs if adequate measures are implemented to reduce triggering exposures and conditions. These include better environmental controls of irritant exposures and accommodations to avoid certain job tasks or locations, such as work in a hot or cold room. Regular monitoring of asthma symptoms and control is important.

Prevention of Work-Related Asthma

Industries using substances that can cause asthma should have measures to control inhalational exposures as much as possible. However, complete elimination is often not possible. Continued exposure can lead to more severe and persistent asthma, underscoring the importance of early recognition of work-related asthma.

Drugs Mentioned In This Article

Generic Name Select Brand Names
Accuneb, ProAir digihaler, Proair HFA, ProAir RespiClick, Proventil, Proventil HFA, Proventil Repetabs, Respirol , Ventolin, Ventolin HFA, Ventolin Syrup, Volmax, VoSpire ER
Aristocort, Aristocort A, Aristocort Forte, Aristocort HP, Aristo-Pak, Aristospan, Azmacort, Children's Nasacort Allergy 24HR Nasal Spray, Cinalog, Cinolar, Flutex, Hexatrione, Kenalog, Kenalog in Orabase, Kenalog-10, Kenalog-40, Kenalog-80, Nasacort, Nasacort AQ, Oralone, SP Rx 228 , Tac-3 , Triacet , Triamonide , Trianex , Triderm , Triesence, XIPERE, Zilretta
Deltasone, Predone, RAYOS, Sterapred, Sterapred DS
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