Aerosolized crab antigens are suspected etiologic agents for asthma among crab processing workers. The goal of this study was to characterize crab antigen levels in processing facilities in relative to the prevalence of respiratory symptoms. Industry and labor representatives in the Northwest have identified respiratory illness, specifically asthma, among those who process crab. In addition, industry representatives have noted difficulty in determining which processing areas may be associated with the greatest risk. UniSea, a Dutch Harbor, Alaska crab processing company, was identified as a research study site to assess the respiratory health of crab processing workers. Specifically, the project goals were to characterize the cross-seasonal changes in respiratory function, as well as determine the incidence of respiratory symptoms, particularly those meeting a rigorous case definition of asthma. The study included pre- and post-season questionnaire administration, pulmonary function testing including methacholine challenge, blood collection to assess immune system responsiveness to crab proteins, and crab antigen exposure assessment.