Occupational exposure to dusts of vegetable or animal origin, often referred to collectively as "organic dust," have been known to give rise to asthma (1). Examples of such exposures include animal confinement areas, baker's flour, insect handling, textile dust, and wood dusts. Although there are more than 200 agents known to cause workplace asthma, with many of the high molecular-weight compounds vegetable or animal in origin, the relationship between long-term exposure to these agents and chronic airway disease is less clear. The clinical conditions generally encompassed by the term chronic obstructive pulmonary disease (COPD) are clearly multifactorial in origin (2); however, besides tobacco smoking, alpha(1)-antitrypsin deficiency was the only other factor accepted as being causally related to COPD in the 1985 U.S. Surgeon General's Report, though host susceptibility factors such as atopic status, airway hyperresponsiveness, and prior respiratory health, as well as environmental factors such as low socioeconomic status, community air pollution and occupational exposures to the development of chronic airway disease has been a subject of considerably more controversy than the contribution of workplace exposures (particularly sensitizers) to the development of asthma.