A systematic review of occupational exposure to respirable coal mine dust (RCMD) in the U.S. mining industry

Cumulative inhalation of respirable coal mine dust (RCMD) can lead to severe lung diseases, including coal worker’s pneumoconiosis (CWP), silicosis, mixed dust pneumoconiosis, dust-related diffuse fibrosis (DDF), and progressive massive fibrosis (PMF). Statistics from the number of reported cases showed a significant decrease in the progression of respiratory diseases in the 1990s. However, an unexpected increase in the number of CWP cases was reported in the late 1990s. To date, there has been no comprehensive systematic review to assess all contributing factors to the resurgence of CWP cases. This study aims to investigate the effects of various mining parameters on the prevalence of CWP in coal mines. A systematic review using the preferred reporting items for systematic reviews and meta-analysis (PRISMA) method was conducted to investigate the health effects of RCMD exposure and identify the factors that may contribute to the recent resurgence of CWP cases. The systematic review yielded a total of 401 papers, which were added to the database. The total number of 148 and 208 papers were excluded from the database in the process of screening and eligibility, respectively. Then, 18 papers were considered for data selection and full-text assessment. The review revealed that factors including geographic location, mine size, mining operation type, coal-seam thickness, coal rank, changes in mining practices, technology advancement, and engineering dust control practices are contributing to the recent resurgence of CWP among coal workers. However, the evidence for root causes is limited owing to the methodological constraints of the studies; therefore, further detailed studies are needed.