[Investigation on the status of respirable dust hazards in underground mines in China].

Objective: To understand the hazard degree of respirable dust (exhaled dust) in coal mine underground workplaces in China, and to provide reference for the prevention and treatment of pneumoconiosis. Methods: A total of 98 representative coal mines were selected from 2016 to 2018, and the dust concentration of the underground working face was detected by the methods of on-the-spot investigation and on-the-spot detection, the dust control measures of 29 coal mines were investigated, and the hazard degree of dust exhaling in the underground working place was analyzed statistically. Results: All 1238 samples of individual coal dust (exhaled dust) were detected in 98 underground coal mines, and the concentration was 4.0 (2.2, 7.3) mg/m(3), the over-standard rate was 73.3% (908/1238) . The concentration of coal dust (exhaled dust) in coal mining face was 5.4 (3.0, 10.6) mg/m(3), and the concentration of coal dust (exhaled dust) in heading face was 3.7 (2.1, 7.2) mg/m(3). The concentration exceeding standard rate of coal dust (exhaled dust) in coal mining face was higher than that in heading face, and the difference was statistically significant ( P <0.05) . Coal seam water injection was found in 57.7% (15/26) coal mining face and 42.9% (9/21) heading face in the application of dust control measures, and the high pressure spray of shearer roadheader only accounted for 38.5% (10/26) and 28.6% (6/21) . Conclusion: The concentration of coal dust (exhaled dust) in the underground face of coal mine is seriously exceeding the standard, and the dust prevention measures have not been put in place.Compulsory standards for classified management of dust in underground coal mines should be formulated, and the research and implementation of dust control technologies should be strengthened.