Comparative Assessment of Physiological Vulnerability Among Male Underground and Surface Coal Mine Workers: A Cross-Sectional Study

Introduction: Underground miners experience exposure to coal dust, poor ventilation, physical effort, stress, and difficult underground conditions, whereas surface miners experience dust and environmental conditions on the ground. This study aimed to compare physiological characteristics, such as cardiovascular, pulmonary, and oxygenation functions among male underground and surface coal miners. Methods: This study compares two groups of men: 90 underground workers (UW) and 90 surface workers (SW). Anthropometric characteristics, blood pressure, peripheral oxygen saturation (SpO2), pulse rate, peak expiratory flow rate (PEF), forced vital capacity (FVC), forced expiratory volume in one second (FEV1), FEV1/FVC ratio, and forced expiratory flow between 25%–75% of FVC (FEF25–75) were measured. Differences between the two groups were analysed using the Welch t-test, Mann-Whitney U test, chi-square/Fisher’s exact test, and correlation analysis. Results: The worker groups were similar in terms of age, body mass index, height, and weight. Underground laborers exhibited significantly higher systolic blood pressure (143.17 vs. 132.39 mmHg; p<0.001), diastolic blood pressure (88.60 vs. 81.47 mmHg; p<0.001), and heart rate at rest (91.04 vs. 77.39 bpm; p<0.001), but significantly lower SpO2 (94.12% vs. 97.40%; p<0.001), PEF (353.24 vs. 455.10 L/min; p<0.001), FVC (2.73 vs. 3.37 L; p<0.001), FEV1 (1.95 vs. 2.74 L; p<0.001), FEV1/FVC (0.713 vs. 0.812; p<0.001), and FEF25–75 (1.93 vs. 2.89 L/s; p<0.001). The prevalence of hypertension, SpO2 < 95%, tachycardia, FEV1/FVC < 0.7, and PEF < 300 was significantly higher in underground miners. Adjusting for age and body mass index, underground work was significantly associated with almost all cardiovascular, oxygenation, and spirometric variables. Conclusion: Underground male coal miners showed significantly higher physiological vulnerability than their counterparts working on the surface evidenced by decreased pulmonary function, low oxygen saturation, increased resting heart rate, and elevated blood pressure.