Coal Workers’ Pneumoconiosis and Related Risk Indices

Abstract

Coal Workers’ Pneumoconiosis and Related Risk Indices: Qiao Niu, et al. Department of Public Health, Shanxi Medical College—Cross sectional epidemiological studies were carried out in three coal mines (Mines A, B and C), that produce differnt types of coal in order to examine the relationship between the prevalence of coal workers’ pneumoconiosis (CWP) and factors contributing to the development and seriousness of CWP. Seven factors were taken into consideration and two of them were calculated as “risk indices”. They concerned composition (including carbon, ash, volatile content of coal, free silica in coal dust and rock dust) and exposure factors (including dust concentration, duration of exposure and type of operation). Composition factors were: carbon 90%, ash 23.13%, volatile content 13.85%, free silica in coal dusts 2.58% and free silica in rock dusts 32.88% in Mine A. Carbon 82%, ash 8%, volatile content 28.5%, free silica in coal dusts 5.90% and free silica in rock dusts 33.0% in Mine B. Carbon 94%, ash 20.46%, volatile content 10.76%, free silica in coal dusts 2.04% and free silica in rock dusts 24.04% in Mine C. Differences in the coal dust concentration over a period of 20 to 30 years were not significant in the three mines. The rock dust concentration in Mine B was much higher than those in the other two mines. The CWP prevalence was 2.22% in Mine A, 13.20% in Mine B and 1.86% in Mine C. Analysis has shown that both composition and exposure factors were related to CWP prevalence, but the strength of the relationship between the factors was different in the three mines, especially in Mine B, where there was a high CWP prevalence, and the association of CWP with free silica and high volatile content was strong. It was interesting that, though the rank of coal in Mine B was much lower than those in Mine A and Mine C, the prevalence of CWP in Mine B was much higher than those in Mine A and Mine C. This result was in contrast with those reported before. The calculation of risk indices indicated that there was a positive correlation between the risk indices and exposure duration.