Characteristics and occupational exposure assessment of VOCs in different coal mines

Introduction The occupational health risk to miners from exposure to volatile organic compounds (VOCs) in underground coal mines has not been adequately quantified. This study aimed to investigate the pollution characteristics and assess the health risks of VOCs in three typical mining areas. Methods VOC concentrations and compositions were monitored and analyzed across different locations (working face, air return tunnel, air intake tunnel) in three distinct mines: Pan San Mine, Qinghai Yuqa Mine, and Hongliulin Mine, which employed different mining and transport methods. Results The main findings were: ① Underground VOC concentrations substantially exceeded surface levels, with peaks of 10.8 mg/m 3 (Pan San), 9.31 mg/m 3 (Qinghai Yuqa), and 14.29 mg/m 3 (Hongliulin) at the working face. A consistent spatial pattern (working face > air return tunnel > air intake tunnel) identified the face as the primary source. ② VOC composition varied with mining methods. In mines using cage elevators or monkey cars, alkane proportions increased by 18.7–23.4% with depth, while OVOCs decreased by 12.1–15.6%, indicating dominant natural emissions from coal seams. In contrast, the mine using diesel transport showed minimal variation (≤4.8%), highlighting the strong influence of mining activities. Discussion/Conclusion The analysis revealed that for the limited subset of VOCs with established occupational exposure limit values (17 of 116), exposure indices were significantly below 1. Furthermore, exposure to the remaining compounds was also negligible. These results indicate that, under the studied conditions, the observed VOC levels did not pose a significant occupational health risk.