Worker health and safety in high-altitude tunnel construction: a study on oxygen supply standards and measures based on physiological indicators

Oxygen supply is a critical factor in ensuring the safety of high-altitude tunnel workers. However, current oxygen supply standards are relatively broad and do not sufficiently account for the varying labour intensities across different construction processes. As a result, workers in high-altitude tunnel construction face increased health risks. This study combines field testing with cycling simulation experiments to evaluate the physiological responses of 50 workers at altitudes between 2,500 and 4,700 meters. Based on the experimental data, optimal oxygen supply standards for different construction processes were established, and targeted oxygen supply measures were proposed. The results demonstrate that as altitude increases, the physiological burden on workers rises significantly, as indicated by higher energy metabolism rates (EPM), elevated heart rates (HR), and lower blood oxygen saturation (SPO2). By developing a multivariate coupling model that links physiological indicators, altitude, and oxygen concentration, specific oxygen supply concentration standards were recommended. Furthermore, an innovative '3 regions + 5 oxygen supply measures' approach for high-altitude tunnel construction was proposed. After implementation, during the six-week monitoring period before and after the intervention, work efficiency improved by 13.6% to 28.6%, and no severe hypoxia cases were reported in this sample. The findings effectively ensure worker safety.