The goal of this SCOR program is to provide the scientific basis for the prevention of fibrotic and immunologic lung diseases which are related to the occupational environment. A multidisciplinary approach is utilized in order to establish causal relationships, dose-response curves, and threshold levels of exposure in lung disorders which are related to the inhalation of mineral and organic dusts, and chemical vapors and gases. Disciplines incorporated in this Center include pulmonary physiology, epidemiology, biostatistics, immunology, chest roentgenography, bioengineering, environmental chemistry and industrial hygiene. Significant emphasis is placed on newer methods of characterizing the inhaled environment which should lead to establishment of those methods which relate best to the indexes of an altered biologic response, and therefore most closely estimate the true exposure dose. The overall significance of this program lies in the fact that these occupational lung disorders are potentially completely preventable, and data from these studies should lead to the establishment of rational occupational environmental standards for hazardous inhalants.