Occupational Asthma

Abstract

Occupational asthma (OA) accounts for up to 20 % of all new cases of asthma diagnosed annually. The definition of OA has expanded to include work-related and work-exacerbated asthma. Hundreds of potential causes have been identified in the workplace, and every year new inciting agents are being reported. High molecular weight agents (molecular weight >1000 kd) are associated with IgE-mediated type I hypersensitivity immune responses. Low molecular weight agents (molecular weight <1000 kd) include a spectrum of chemicals, some of which can react with endogenous proteins to form a new allergen capable of inducing an IgE-mediated response, but frequently these agents induce irritant-induced asthma also known as reactive airways dysfunction syndrome. Successful management of OA requires a comprehensive medical history including details about the worker’s job process and workplace exposures as well as establishing an objective diagnosis of asthma. It is also important to assess potential risk factors such as atopy. In vitro serologic testing and in vivo skin testing may be helpful in supporting a diagnosis of OA but are not diagnostic. The gold standard for diagnosis is specific provocation which may not always be possible or feasible but when performed should be conducted in a controlled medical environment under the supervision of someone with medical expertise in this area. Management of OA requires removing the worker from further exposure and treatment with medications similar to non-OA. Immunosurveillance programs have been established in some industries which have been very successful in monitoring workers exposed to potentially sensitizing agents to prevent sensitization and the subsequent development of OA.