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October 20, 1956


JAMA. 1956;162(8):715-719. doi:10.1001/jama.1956.02970250015005

• Of 230 soft-coal miners who presented some form of cardiorespiratory symptoms, over half were found to have x-ray evidence of coal workers' pneumonoconiosis. These findings, over a one-year period, and repeated in the following year, showed the incidence of this condition represented almost 31 % of a total hospital population of coal miners. This deposition of coal dust and fibrosis, which can cause disability and even death, is significantly different from classic silicosis therapeutically and prognostically.

Chest x-rays alone, while presenting characteristic lesions, do not necessarily indicate the degree of disability. Vital capacity, timed vital capacity, and maximal breathing capacity, expressed as a percentage of the estimated normal, appear to demonstrate disability inversely proportional to the decrease in maximal breathing capacity. Miners who had less than 35% of the estimated normal could do little more than walk slowly on a level plane. The studies seem to indicate that this condition poses a significant hazard to those in the coal industry.