Key points
- Manual material handling is consistently the leading cause of non-fatal strain and sprain injuries in mining.
- To address these hazards, NIOSH has performed audits, conducted analysis, and created safety principles and documentation.
- After an uptick in mining-related knee injuries, NIOSH created a knee pad for low-seam mining environments.
Hazard
Manual material handling (MMH) is the leading cause of nonfatal injuries in mining. It is the process of routinely moving and handling objects by:
- Carrying
- Holding
- Lifting
- Pulling
- Pushing
- Stooping
MMH is performed by many types of workers in surface and underground mining including:
- Maintenance workers
- Electricians
- Mechanics
- Laborers
- Some equipment operators
Workspace constraints, common in underground mining, contribute to injury risk for workers performing MMH tasks.
Sprains or strains are the leading type of non-fatal injuries in mining for MMH. According to a study comparing 1983–1984 and 2003–2004 MSHA data, the percentage of cumulative injuries was similar (37% and 33%). However, many more work days were lost due to injury in 2003–2004. Cumulative back injuries decreased by 10%, potentially due to use of assist devices. Cumulative knee injuries increased by 8%, possibly a result of kneeling/crawling in low-seam mines.
The most common MMH activities that were the primary sources of non-fatal days lost injuries were:
- Handling supplies or material load and unload (45%)
- Machine maintenance/repair (24.3%)
- Handling coal, rock, waste or ore (5.3%)
- Move power cable (4.5%)
- Hand shoveling/mucking (3.8%)
- Get on or off equipment machines, etc. (3.0%)
- Moving equipment (1.7%)
The top five sources of MMH injury include:
- Metal not elsewhere classified (pipe, wire, nails, manhole covers) (17.8%).
- Metal covers and guards (14.8%)
- Broken rock, coal, ore, waste (9%)
- Belt conveyors (4.6 %)
- Conductors, electric cables and trolley poles (4.6 %)
What NIOSH is doing
Ergonomics
NIOSH research has been designed to provide tools to help mines identify risk factors. The tools also help implement and audit ergonomics processes, as well as provide specific interventions to address ergonomics problems in mining. Two recent projects involved developing ergonomics audits for specific types of operations:
- Haul truck operation
- Bagging operations
- Maintenance and repair in processing and preparation plants
Additionally, the projects involved developing a knee pad for low-seam mining environments.
These projects used a mix of laboratory and field investigations to assess the problems and develop guidelines for remediating ergonomics issues. Another recent project assessed injuries sustained by mine workers when handling machine covers and guards.
Interface job design
Equipment design refers to overall design specifications. Additionally, equipment design includes the components and interface used by mine workers to do their jobs and to maintain the equipment. The types of injuries related to equipment design include repetitive strain such as whole body vibration and overexertion.
Much work has been accomplished in the area of seating and whole body vibration effects on health and safety. NIOSH is developing and conducting testing in the areas of proximity warning systems. The testing will provide operators with the knowledge of how close they are to hazards in and around equipment. This will help operators make better decisions for their own health and safety. Additionally, an audit program is currently underway. The audit program aims to help mines to evaluate their equipment and jobs to reduce musculoskeletal injuries.
NIOSH is also conducting tests in the area of controls design to help limit acute injuries. The tests focus on injuries caused by operators inadvertently activating the incorrect control or the correct control in the wrong direction.
Significant findings
Ergonomics
Cumulative injuries are a major financial burden to the industry. Using NIOSH-developed tools for incorporating ergonomics in the workplace was shown to be a tremendous success. The success indicated that ergonomics can be used to reduce injuries and costs.
NIOSH Mining has published two Information Circulars publications on ergonomics processes and participatory methods for mines:
Practical Demonstrations of Ergonomics Principles was developed to provide safety trainers with several demonstrations for teaching ergonomics principles to mine workers.
With attention focused on the knee, NIOSH published on preventing injury in Keeping Knees Healthy. NIOSH summarized experimental investigations of pressures and moments on the knee during different activities and while wearing different knee pads. It details stress distributions while wearing commonly-worn knee pads. Additionally, it details physiological and biomechanical responses due to different postures and modes of locomotion.
The audits have been published as printable PDFs as well as the ErgoMine Android application for phone and tablet. The app is free and available in the Google Play store. Several recommendations that stemmed from these audits can be found in the Simple Solutions document that can be downloaded and printed.
NIOSH conducted an analysis of injuries associated with machine maintenance and discovered that machine guards caused a significant number of injuries. Machine guards are designed to protect mine workers from dangerous work areas or equipment. However, the guards are often heavy pieces of solid metal. These pieces of metal can require significant physical exertion if a mine worker has to remove the guard to perform maintenance. NIOSH suggests reducing the size and weight of machine guards to reduce injuries related to machine maintenance.
Slips, trips, and falls
Slips, trips, and falls are the second largest contributor to non-fatal injuries in the U.S. mining industry such as:
- Strains
- Sprains
- Other injuries
Mine operators have indicated problem areas such as footwear and ingress/egress from mobile equipment as potential sources of slips, trips, and falls hazards. The exact elements of these sources that pose a risk are still largely unknown. To address these issues, NIOSH is studying slips, trips, and falls hazards at mining facilities to help identify and remediate these hazards. As part of this study, researchers examined 20 years of injury data. Researchers found that a considerable number of injuries occurred when operators were getting off of front-end loaders. Most often when the operator was on the ladder or steps. Researchers recommend:
- Ensuring consistent rung heights on ladders
- Providing designated parking areas free of hazardous ground conditions
- Providing adequate lighting and handholds
- Using stairs instead of ladders
- Completing regular inspections
- Maintaining ingress/egress systems
Next steps
NIOSH will continue to research safe practices and solutions to reduce MMH.
The slips, trips, and falls project is continuing to investigate hazards in mining facilities. Researchers are examining the influence of metatarsal boots on ascent and descent of inclined walkways and stairs. A longitudinal study of boot wear is also in progress. The study aims to provide mining operations with knowledge to determine when to replace footwear. NIOSH researchers are actively working to help mining companies reduce slip, trip, and fall hazards in their work environments.