This study was designed to examine whether retail food store employees have an unusual prevalence or incidence of respiratory symptoms or pulmonary function abnormalities attributable to their work environment. The methodology and development of exposure assignments are presented. Employees from 75 supermarkets (a total of 685 meat cutters, wrappers and store clerks) were tested in a base-line survey, and those still available (305) were resurveyed four years later. Each subject completed a standard questionnaire on job history, health history, cigarette smoking, and respiratory symptoms and also performed five forced expiratory efforts on a standardized spirometer. The major air contaminants were identified including the composition and levels of exposures associated with the different ways of cutting plastic film wrap. A cumulative exposure estimate for each subject was made. Parts II and III of this study present the association of these work environment factors with respiratory symptoms and ventilatory function.