In May 1982, 606 adults volunteered to participate in studies involving human exposures to card-generated cotton dusts at the USDA Cotton Quality Research Station in Clemson, SC. Using baseline spirometry and a standardized questionnaire, subjects with medical contraindications or potentially confounding occupational exposures were excluded from further participation. During each of two subsequent weeks, remaining subjects were scheduled to undergo one exposure to card-generated dust from commercially-available, strict low middling Mississippi-grown (Cotton Quality Research Station Study # MQBO) cotton, and one exposure to a clean room, with spirometry measured immediately before and after each exposure. This paper presents a summary of the acute exposure-related respiratory reactions, including prevalences of dust-related respiratory symptoms and objective changes in forced expiratory volume in one second (FEV(1)). The importance of several host factors -- sex, race, age, smoking status, baseline FEV(1)/FVC ratio, and history of prior cotton textile mill work -- are examined as determinants of the acute response to inhaled cotton dust.