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Occupational Asthma

Occupational asthma is a disease that results from exposure to sensitizing agents in the workplace. Roughly 10% of adults who have asthma are estimated to have occupational asthma. Occupational asthma is usually diagnosed by a specialist and there are certain conditions that have to be met to secure a diagnosis. They include:

  • Exposure to a sensitizing agent
  • An intial symptom-free period of exposure
  • Improvements in symptoms when away from work

Not everyone exposed to the same sensitizing agent or in the same occupation will develop occupational asthma. To determine whether you’ve developed occupational asthma, ask yourself the following questions:

  • Did your asthma symptoms appear within weeks or months of starting a new job, or moving to a new area within your current job?
  • Do your asthma symptoms regularly and predictably occur while you’re at work or within a few hours of leaving the workplace?
  • Do you notice that your symptoms improve on weekends or when you’re on vacation, and then get worse when you go back to work?
  • Do other people at work have the same symptoms?

If you suspect you have occupational asthma, talk to your doctor, who may refer you to a respirologist for further assessment.

If your employer has taken every preventive measure possible and your symptoms are still severe, you may have to consider switching careers. Remember, you can always talk to your healthcare provider if you think your job is making you sick. You can learn more about occupational asthma here.

Who Gets Occupational Asthma?

A previous history of asthma is not a risk factor for occupational asthma. The latency period varies considerably from person to person, sometimes taking years before the occupational asthma shows up. There is a long list of occupations that are most at risk for the development of occupation asthma including animal breeders, bakery workers, carpenters, hairdressers, farmers etc.

If you have any of the following jobs, you may be at risk for occupational asthma:

Grains, flours, plants and gums

  • Bakers, chemists and farmers

Animals, insects and fungi

  • Poultry workers, entomologists, laboratory workers and veterinary professionals


  • Aircraft fitters, brewery workers, pulp mill workers, electronic workers, hairdressers, refrigeration workers, resin manufacturers and dye weighers

Isocynates and metals

  • Car sprayers, boat builders, foam, TDI and refrigerator manufacturers, platinum chemists and refiners, printers and laminators and welders

Drugs and enzymes

  • Ampicillin, detergent and enzyme manufacturers, pharmacists and pharmaceutical workers


  • Carpenters, millers, saw-mill workers, wood finishers and machinists

You can learn more about occupational asthma on the Canadian Centre for Occupational Health and Safety (CCOHS) website by clicking here.

Indoor Triggers

Asthma & Allergy HelpLine

Outdoor Triggers

Breath Easy: Triggers

Download a copy of our Breathe Easy Booklet Series on asthma triggers. It provides useful information on managing your asthma, avoiding triggers and staying symptom-free . [Click here to download in French].