Occupational asthma (OA) is a form of work-related asthma that is characterized by variable airflow obstruction, airway hyperresponsiveness, and airway inflammation induced by exposures in the work environment rather than exposures encountered outside the workplace . Work-exacerbated asthma (also known as work-aggravated asthma) is defined as preexisting or concurrent asthma that subjectively worsens in the workplace.
The agents that cause OA include both immunologic and nonimmunologic stimuli . Immunologic OA is the classic form of OA in which the worker’s immune system is sensitized to an occupational agent through IgE-mediated or other immune recognition. Nonimmunologic OA is a form of irritant-induced asthma that results from single or multiple exposures to a nonimmunologic, irritant substance at a high level of intensity. Reactive airways dysfunction syndrome (RADS), a form of irritant-induced asthma, is triggered by an acute high level exposure to a nonimmunologic stimulus.
The diagnosis of OA is based on the appearance of new adult-onset asthma since the time of initial occupational exposure to a causative agent, evidence of reversible airflow obstruction (based on pulmonary function testing), and demonstration of sensitization to a potential causative agent.
The management, prognosis, and prevention of OA will be reviewed here. The definition, epidemiology, causes, risk factors, pathogenesis, clinical features, evaluation, and diagnosis of OA, and the diagnosis and management of RADS and irritant–induced asthma are discussed separately. (See "Occupational asthma: Definitions, epidemiology, causes, and risk factors" and "Occupational asthma: Pathogenesis" and "Occupational asthma: Clinical features and diagnosis" and "Reactive airways dysfunction syndrome and irritant-induced asthma".)
The key element is to make the diagnosis and remove the subject from exposure as quickly as possible after the onset of symptoms. OA can be cured if this is done rapidly and efficiently. The management of OA requires a combination of avoidance of further exposure to sensitizing agents, reduction in exposure to irritant agents (eg, environmental tobacco smoke, strong fumes and fragrances, extremes of temperature and humidity) and pharmacotherapy based on the severity of asthma. The management of occupational rhinitis, which may accompany OA, is discussed separately. (See "Occupational rhinitis".)