Asthma is a chronic (long-term, ongoing) inflammation of the breathing passages (bronchi) of the lungs. The inflammation irritates the airway, causing breathing problems. Asthma is triggered by external factors or specific situations. When a person with asthma is exposed to one of his or her triggers, the inflammation worsens and symptoms ensue. Most people with asthma have sudden attacks or periods of bothersome or severe symptoms separated by periods of mild symptoms or no symptoms at all.
Occupational asthma is caused by exposure to a trigger in the workplace. The list of known triggers is long and varied, although they are generally substances that are inhaled.
For many people, asthma attacks may happen more often in the winter.
"There are two challenges for people with asthma in the winter. One is that they spend more time inside. The other is that it’s cold outside," says H. James Wedner, MD, an asthma expert at Washington University in St. Louis.
While you’re indoors, you breathe in asthma triggers such as mold, pet dander, dust mites, and even fires in the fireplace. When you venture out, you could have an asthma attack from inhaling the cold air...
Aggravation of preexisting asthma: This is by far the most common type. Over time, with regular exposure, you develop hypersensitivity to the trigger. With this underlying asthma, continued exposure to the trigger causes attacks.
Irritant asthma: Exposure to certain substances or conditions in the workplace irritates the airways, causing immediate symptoms. Although this is not an allergic-type reaction, the irritation may cause allergy-like or asthma-like symptoms.
Once the attack is triggered, the airways begin to swell and tighten (bronchospasm) and secrete large amounts of mucus. The swelling and extra mucus partially block, or obstruct, the airways. This makes it more difficult to push air out of your lungs (exhale).
Early recognition and avoidance of the asthma trigger is particularly important in occupational asthma.
Because people spend so much time at work, those with occupational asthma tend to have extensive exposure to their trigger by the time the cause of the symptoms is recognized as asthma. The more time you spend exposed to your trigger, the more likely you are to have permanent lung inflammation and airway hypersensitivity.
Occupational asthma is the most common work-related lung disease in developed countries. In up to 15% of people with asthma in the United States, the condition is at least partly related to their work.