Occupational asthma (OA) is a form of work-related asthma characterized by variable airflow obstruction, airway hyperresponsiveness, and airway inflammation attributable to a particular exposure in the workplace and not due to stimuli encountered outside the workplace [1,2]. Two types of OA are distinguished based on their appearance after a latency period: (1) OA caused by workplace sensitizers: allergic or immunological (with a latency period); (2) OA caused by irritants: nonallergic or nonimmunologic, irritant-induced asthma including reactive airways dysfunction syndrome (RADS).
Occupational asthma accounts for approximately 10 to 25 percent of adult onset asthma [3,4]. 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.
The definition, epidemiology, causes, and risk factors of OA are reviewed here. The pathophysiology, clinical assessment, diagnosis, and management of OA and reactive airways dysfunction are discussed separately. (See "Occupational asthma: Pathogenesis" and "Occupational asthma: Clinical features and diagnosis" and "Reactive airways dysfunction syndrome and irritant-induced asthma".)
Several terms are used to define the various forms of work-related asthma :