Abstract

This project undertook a retrospective study of the long-term evolution of respiratory function in silicosis victims compensated by the CSST (Commission de la santé et de la sécurité du travail du Québec, Québec Occupational Health and Safety Commission). The study group was composed of 107 workers having undergone at least four examinations within the last six years, and was drawn from an initial group of 980 workers for whom respiratory function measurements were available. No difference was observed between the age-specific rate of decrease of vital capacity in affected and unaffected subjects. The vital capacity at the time of diagnosis was within normal limits in 78.6% of workers, and abnormal in 21.6% of workers. On average, vital capacity decreased by 410 ml, or 10% of the predicted capacity. Similar results were observed with resting carbon monoxide diffusing capacity. As well, average blood oxygen pressure of silicosis victims, at rest and during moderate exercise on a treadmill was almost normal, varying between 79 and 76 mm Hg during the 12-year observation period, while the average age of workers rose from 47 to 59 years.