You can develop asthma in response to a chemical or allergen exposure at work. Here's a partial list of the substances found in the workplace that can trigger asthma symptoms:

• Animals — Furry animals can expose laboratory workers, farmers and veterinarians to allergens. For people who are susceptible, long-term exposure to pigeons, birds or chickens in breeding areas or poultry plants can trigger an allergy reaction that imitates pneumonia, called hypersensitivity pneumonitis.
• Tobacco — Bars, clubs, and some restaurants are among the workplace locations where cigarette smoke exposure may be substantial. Second-hand smoke inhalation is a common cause of occupational asthma.
• Paints, plastics, foams and glues — The chemicals toluene diisocyanate, diphenylmethane and anhydrides are present in certain paints, resins or varnishes and are released during the production of some polyurethane foams and plastics. Ethanolamines can be released when some paints are applied.
• Hospital exposures — Formalin and latex are common asthma or allergy triggers in hospitals.
• Crustaceans — Crabs and shrimp in food-processing plants have been reported to trigger allergy.
• Enzymes — Trypsin and papain are used in some detergents, in meat processing and in the manufacture of drugs by the pharmaceutical industry.
• Metals — Platinum, nickel, chromium, cobalt and vanadium are used in metal plating, leather tanning and the metal refining industry. Soldering may also release ethanolamines.
• Grains — Grain dust and baking flour found in grain mills and grain-handling areas can trigger asthma.
• Soldering — Colophony (pine resin) and ethanolamine have triggered symptoms after soldering. This is a concern in the electronics industry.
• Vegetable products — Gum acacia may be an exposure within printing plants.
• Wood dust — Cedar and redwood dust are present in carpentry shops, construction sites and wood mills.

If your asthma symptoms are triggered by exposure to any of the substances you encounter at work, you may have occupational asthma.

If you think you might have this form of asthma, track your symptoms in a diary. You might notice you feel improved when you're away from work (especially during weekends and vacations), or you might go to work feeling relatively well but notice that your breathing changes toward the end of the day. Symptoms generally improve at home until the next time you go to work.

There is a wide range of severity for occupational asthma — not all require a change in occupation (although this is ideal). You may be able to control your asthma by making changes in the workplace, such as moving to an area where you won't inhale the irritating materials, or using a personal respirator. Depending upon the type of reaction that you have had, it may take as long as two years for your symptoms to disappear after you eliminate exposure. If you don't reduce or eliminate your exposure, your asthma is likely to worsen. Less severe occupational asthma symptoms can be controlled with medication. If you have asthma symptoms, be sure to tell your doctor about the irritants and chemicals you are exposed to at work, because occupational asthma is often misdiagnosed as chronic bronchitis or chronic obstructive pulmonary disease.