Occupational Asthma

Types of work-related asthma

See reactive airways dysfunction for irritant-induced asthma.

Common causes and jobs at risk

More than 400 workplace substances can cause occupational asthma.

Symptoms

• wheezing
• cough, often dry
• chest tightness
• shortness of breath
• runny nose, sneezing and itchy eyes (occupational rhinitis, a form of allergic rhinitis), often months before asthma
• symptoms worse during or after work, sometimes delayed to the evening or night, and better on days off and vacations

The pattern can blur over time: in long-standing cases, symptoms may not improve on short breaks.

Diagnosis

Early, accurate diagnosis is important because of the consequences for health and employment.

1. Detailed work history: job tasks, materials used, when symptoms started, improvement away from work, coworkers affected. Safety data sheets help identify agents.
2. Confirming asthma: spirometry before and after a bronchodilator, and methacholine challenge testing.
3. Linking asthma to work: - serial peak flow monitoring: recording peak flow at least 4 times a day for several weeks, at work and away - lung function tests or methacholine challenge done after a period at work and after time away - skin-prick or IgE blood tests for some sensitizers, such as flour, latex and animal proteins - specific inhalation challenge in specialized centers
4. Sputum eosinophil counts at and away from work, in some centers.

Diagnosis should be made while the person is still working, if possible, because testing after leaving work is less reliable.

Treatment

Removing exposure

For sensitizer-induced asthma, complete avoidance of the causative agent offers the best chance of improvement or cure. Options:

• substituting a safer material
• engineering controls: enclosure, local exhaust ventilation
• moving to a different role or location without exposure
• respiratory protective equipment is not a reliable substitute for removing exposure for sensitized workers

For irritant-induced or work-exacerbated asthma, reducing exposure may be enough.

Asthma medicines

Standard treatment following asthma guidelines:

• inhaled corticosteroids, often combined with a long-acting bronchodilator
• reliever inhalers
• biologic therapies for severe asthma

Medicines control symptoms but do not replace avoiding the cause.

Work and legal considerations

Workers have rights. In the US, OSHA requires employers to protect workers from hazardous exposures, and occupational asthma may qualify for workers' compensation. An occupational medicine physician can help with workplace adjustments and documentation.

Outlook

People who are diagnosed early and removed from exposure soon after symptoms start are most likely to improve. Even after removal, many continue to have some asthma, especially if they were exposed for a long time after symptoms began. Continued exposure leads to worsening and permanent asthma.

Prevention

• substitute less hazardous materials where possible
• use enclosed processes and ventilation
• provide training, safety data sheets and appropriate respiratory protection
• use powder-free, low-protein latex gloves or non-latex alternatives
• protect the skin too, since the same agents can cause occupational dermatitis
• health surveillance for workers in high-risk jobs, with questionnaires and lung function checks
• report early nose, eye or chest symptoms

See asthma for general information on asthma symptoms and treatment.

Frequently asked questions

What is occupational asthma?

Occupational asthma is asthma caused by breathing in substances at work, such as dusts, fumes, gases or vapors. It causes wheezing, coughing, chest tightness and breathlessness that are typically worse at work and better on days off.

What are the most common causes of occupational asthma?

Common causes include isocyanates in spray paints and foams, flour and grain dust, latex, wood dust, cleaning chemicals, animal proteins, hair dye chemicals, and metal and solder fumes. More than 400 workplace agents have been linked to it.

How is occupational asthma diagnosed?

Doctors confirm asthma with breathing tests and then link it to work using a detailed job history, serial peak flow readings at work and away from work, allergy tests for some agents, and sometimes specialized challenge tests.

Can occupational asthma go away?

It can improve or resolve, especially if the exposure is removed early. Some people continue to have asthma even after leaving the job, particularly after long exposure. Continuing to work with the cause usually makes asthma worse.

Do I have to leave my job if I have occupational asthma?

Not always. Sometimes the substance can be replaced, ventilation improved, or you can move to a role without exposure. For sensitizer-induced asthma, complete avoidance of the specific agent is needed. An occupational medicine specialist can help with options.