Occupational asthma is characterized by variable airflow limitation and airway hyper responsiveness due to conditions related to a particular occupational environment. There are two types of occupational asthma -- nonlatent and latent -- distinguished by when symptom onset occurs; immediately after an exposure or after a prolonged or latent period, respectively. The latent form primarily refers to the "classic" sensitizer-induced immunologic form of occupational asthma. It usually occurs following exposure to either a high- or low-molecular-weight antigen in the workplace, but symptoms manifest only after a prolonged period. There are certain forms of occupational asthma with latency for which an immunologic mechanism has not been identified (eg, meat wrappers' asthma and pot room asthma).
Occupational asthma accounts for approximately 10 to 25 percent of adult onset asthma. In the case of allergic OA, a high degree of clinical suspicion is needed as the latency period for sensitization varies from a few months to several years, depending on several factors, including the intensity of exposure, the specific sensitizing agent, and individual susceptibility. It's important that occupational asthma be diagnosed and the patient avoids further exposure, because most patients with occupational asthma will get worse over time if they remain exposed. Occupational asthma can be treated the same as regular asthma, with inhaled medicines called bronchodilators that open (dilate) the airways as well as inhaled anti-inflammatory medicines (glucocorticoids).