Ergonomic Risk Assessment of Manual Drilling in an Underground Copper Mine: Fatigue Assessment

Aims: This study evaluated manual drilling to identify high-risk activities and quantify the risks of muscle fatigue and cumulative low back injury.
Method and Materials: This descriptive study involved direct observation of a full work shift. Three tools were used including Hierarchical Task Analysis (HTA) to deconstruct and time tasks, Muscle Fatigue Assessment (MFA) to identify high-risk body parts, and the Lifting Fatigue Failure Tool (LIFFT) to calculate cumulative damage to the low back from lifting tasks.
Findings: The HTA revealed that the drilling the wall task was the most time-consuming, accounting for 50% of the total shift time. The MFA results identified this task as posing a very high risk priority for the shoulders and back, and a high risk for the wrists/hands/fingers. The LIFFT analysis yielded a cumulative damage score of 0.09895, which corresponds to an approximate 67% probability of low back injury, classifying the job as high-risk. The tasks of drilling and moving tools contributed to over 99% of the total cumulative damage.
Conclusion: Manual drilling is a high-risk occupation with significant ergonomic hazards for the shoulder, back, and upper limbs. The alignment of these results with epidemiological data validates the assessment. Targeted interventions to reduce biomechanical loading are strongly recommended to mitigate the high risk of musculoskeletal disorders.