Occupational Ergonomic Risks Among Women in Underground Coal Mining, South Africa

Abstract

Although women have participated in mining activities across the world for centuries, the industry continues to be perceived as predominantly male-oriented. This perception persists largely due to the male-dominated workforce and the physically demanding nature of mining operations. This paper examines the ergonomic impacts of mining machinery on female mineworkers. The study was conducted in three underground coal mining operations located in Mpumalanga, South Africa, using a quantitative research approach. To evaluate the ergonomic demands placed on women working underground, the researchers employed the Rapid Entire Body Assessment (REBA) in combination with direct observation techniques. The findings revealed that female mineworkers experience considerable challenges when performing tasks requiring significant physical strength and endurance. The observed female mineworker recorded a final REBA score of seven, indicating a medium-risk level. Ergonomic challenges in underground coal mining are further intensified for female mineworkers due to the absence of gender-specific considerations in equipment design, task allocation, and the overall working environment. Although the risk classification was moderate, the results underscore the need for further investigation and the timely implementation of corrective measures. Addressing these issues will require the integration of inclusive ergonomic principles that account for gender diversity within the mining workforce.

1. Introduction

On a global scale, construction, agriculture, and mining are among the most dangerous industries [1]. In every sector, businesses need to enforce safety protocols to prevent accidents and occupational diseases. The activities and processes within these industries pose significant risks to both human health and safety [2,3]. Despite these dangers, mining remains a crucial source of global revenue [4,5], with the production of metals and coal being essential for modern society. These resources are vital for energy, housing, technology, and the creation of new alloys that enhance human life [6]. Investments in mining stimulate economic growth by creating both direct and indirect employment opportunities, promoting social development through various initiatives, significantly improving communities, and aiding in poverty alleviation [7]. Over recent decades, the mining industry has shifted from manual labour to more mechanized operations, resulting in a reduction in the physical demands of work. Nevertheless, workers still perform manual tasks such as installing overhead pipes, cables, and ventilation systems in underground mines, setting up and dismantling conveyor systems, and cleaning and maintaining machinery. They must continuously operate drilling machines, position roof bolting machines in uncomfortable positions, and often twist their necks and hands when using loaders, leading to musculoskeletal strain. Mineworkers frequently work in tight, low-ceiling spaces with poor lighting, forcing them into awkward postures that place significant stress on their musculoskeletal systems, with female mineworkers being particularly affected.

While mechanization has greatly boosted production, it has also brought about new safety risks and occupational hazards, particularly the neglect of ergonomic practices, which contributes to the high incidence of musculoskeletal disorders [8]. Ergonomic Regulations define ergonomics as a scientific discipline focused on understanding the interactions between humans and system elements and applying this knowledge to optimize human well-being and system performance [9]. The International Human Factors and Ergonomics Society (IHFE) outlines that ergonomics encompasses physical ergonomics, cognitive ergonomics, and organizational ergonomics, each addressing different aspects of human interaction with work systems [10]. With that highlighted, a significant ergonomic challenge in mining is the absence of gender-inclusive design in mining equipment. Many machines, such as roof bolters, load haul dumpers (LHD), and shuttle cars, are primarily designed with male body dimensions in mind, often overlooking the smaller size and physical strength of female workers. Mining equipment, particularly in narrow mines, tends to have operator cabins that are often tailored for male workers, leading to poor posture and discomfort for female mineworkers, who may have shorter limbs and smaller body frames [8]. These environmental conditions have the potential to contribute to musculoskeletal disorders (MSDs) among female mineworkers. Musculoskeletal disorders refer to conditions that affect the body’s muscles, bones, tendons, ligaments, nerves, and other supporting structures [11]. These disorders often arise from factors such as excessive physical strain, improper posture, repetitive motions, or extended exposure to vibrations [12]. Pursuantly, gender differences also exist regarding the aerobic capacity of men and women which aggregates the effect of ergonomic exposure of female mineworkers. Ashworth et al. [13] define aerobic capacity as the maximal oxygen uptake that provides a quantitative measure of a person’s ability to sustain high-intensity physical work for longer than five minutes. This implies that aerobic capacity of women is typically 15 to 30% below the values of their male counterparts. This means that women work closer to their aerobic capacity than men and are thus more likely to become fatigued. Fatigue is operationally defined as the ‘reduced muscular ability to continue an existing effort [13]. High levels of fatigue can reduce performance and productivity in the workplace and increase the risk of accidents and injuries occurring [14]. Furthermore, due to women’s inability to perform mine work that requires physical strength and stamina, management and male mineworkers experience unique frustrations and challenges. According to Jager et al. [15], average lifting capacities for women range between 20–30 kg for repetitive tasks, whilst their male counterparts are higher than that. The inclusion of women in these mining processes has highlighted concerns regarding the impact of high-energy tasks on their well-being.

Over the past 40 years, various observational methods have been developed to evaluate risk factors linked to work-related musculoskeletal disorders (WMSDs). These methods can assign numerical values to different work postures and provide an overall indicator of the severity of postural risks, helping designers or decision-makers implement changes in work processes, as well as in the design of machinery and workspaces [16]. This paper aims to highlight the effects of inadequate ergonomics and poorly designed machinery on female mineworkers. It specifically concentrates on physical ergonomics and the associated risk of developing musculoskeletal disorders. The focus of this study was intentionally limited to female mineworkers, as the primary aim was to explore gender-specific ergonomic challenges and postural adaptations in an underground mining environment that has traditionally been designed around male anthropometry. While the authors acknowledge that the confined nature of the machine cabins could affect both male and female operators, the impact differs due to variations in body dimensions, reach distances, and seating fit [17].

2. Materials and Methods

2.1. Study Area

There are 19 identified coalfields in South Africa, predominantly located in the north-eastern regions of the country, specifically within Mpumalanga, Limpopo, KwaZulu-Natal, and the Free State provinces [18]. Most of the coal production originates from the Witbank and Highveld coalfields, which collectively contribute approximately 75% of South Africa’s total coal output [18]. The Witbank coalfield hosts the highest concentration of coal mines [18]. Coal extraction in South Africa primarily employs two mining methods: surface (opencast) mining and underground mining [19]. The mines included in this study utilize mechanized bord-and-pillar techniques for underground operations and employ approximately 1200 to 1600 workers each. One of the mines that participated in this study is in Witbank, while the other two are situated approximately 40 km away. Continuous miner machines are used for coal extraction, and operations are conducted in three rotational shifts of 8–9 h a shift. For confidentiality, the mines are referred to as Mine “A,” Mine “B,” and Mine “C.” The sites were selected based on convenience sampling, a method chosen for its practicality, simplicity, and cost-effectiveness [20]. Figure 1 illustrates the geographic distribution of coal mines in South Africa, highlighting that the majority are concentrated in Mpumalanga province, the selected study area.

2.2. Population and Sampling Size

Underground coal mining was the preferred area for the study since the literature shows little evidence of research in underground coal mining, especially research focusing on female ergonomics in underground coal mines. This paper examined female mineworkers who operate machinery, specifically roof bolters and shuttle cars, as well as those performing general duties like handling continuous miner (CM) cables. The activities mentioned were chosen because the researcher aimed to focus specifically on participants operating machinery and performing general section tasks. This focus was influenced by time constraints; however, it is important to note that this paper represents only a portion of a larger study. The observations were conducted on six female miners who voluntarily participated in the study, were on duty on the day of observation, and held valid machine licences. Although the sample size for this segment was small (n = 6), it is not strictly an exploratory study because this paper forms part of a larger, ongoing study with a broader dataset. The sections were in operation during the observation period. Participation was limited to female mineworkers on the morning shift, in accordance with the agreement established between the researcher and management. The six women across the three different mines (two from each mine) were evaluated using the Rapid Entire Body Assessment (REBA) tool. Among them, three were roof bolter operators, two drove shuttle cars, and one was responsible for hanging the CM cable. Participants were selected using convenience and purposive sampling, a non-probability sampling technique where individuals are chosen based on the researcher’s assessment of their relevance to the study [21]. This ergonomic assessment tool uses a systematic process to evaluate whole body postural Musculoskeletal disorder (MSD) and risks associated with job tasks. A single-page worksheet is used to evaluate the required or selected body posture, forceful exertions, type of movement or action, repetition, and coupling. Its reliability was also evaluated in 2019 by Schwartz et al. [22]. Moreover, it has been compared to other methods, raising the possibility of creating a comprehensive method for all work tasks and all body parts. The REBA was designed for easy use without the need for an advanced degree in ergonomics or expensive equipment [23]. A quantitative ergonomic (postural) analysis was conducted using the REBA method to assess and score musculoskeletal disorder (MSD) risk levels for different body regions. Using the REBA worksheet, the evaluator was able to assign a score for each of the following body regions: wrists, forearms, elbows, shoulders, neck, trunk, back, legs and knees. After the data for each region is collected and scored, tables on the form were then used to compile the risk factor variables, generating a single score that represents the level of MSD risk; see Figure 2 and Figure 3 and

Table 1. MSD risk rating [24].

Score	Level of MSD Risk
1	Negligible risk, no action required
2–3	Low risk, change may be needed
3–7	Medium risk, further investigation, change soon
8–10	High risk, investigate and implement change
11+	Very high risk, implement change

The color coding highlights the level of risk: green indicates everything is fine, orange signals that attention or action is required, and red denotes a high-risk situation where changes need to be made promptly.

below for REBA scoring explanation:

This paper aims to highlight the effects of inadequate ergonomics and poorly designed machinery on female mineworkers. It specifically concentrates on physical ergonomics and the associated risk of developing musculoskeletal disorders. This study supports SDG goal number 5, achieving gender equality and empowering all women and girls.

Inclusion criteria: Women engaged in core underground coal mining roles, such as machine operators and general underground female workers.

Exclusion criteria: Women working in mining sectors other than underground coal mining, as well as those employed in underground coal mining but performing non-core tasks.

2.3. Ethical Approval

Firstly, the researcher received ethical approval from the Tshwane University of Technology (REC Ref #: REC/2023/05/007). Secondly, permission was requested from mine management to conduct the research; then, the researcher visited the research settings to explain the details of the study and to get consent from workers, which was to align with the POPI Act. The following ethical practices were considered: voluntary participation, informed consent, privacy, anonymity, and confidentiality.

3. Results

One of the most pressing ergonomic issues is the lack of gender-inclusive design in mining equipment. Many machines, such as roof bolters, shuttle cars, and Load-haul-dumps (LHD), are designed with male body dimensions in mind, often disregarding the stature and physical strength of female workers. Figure 4 and Figure 5 show female mineworkers operating shuttle cars. It can be observed that the sitting position is not neutral due to the way in which the cabins are designed, which poses the risk of spinal injuries as well as back pains. The region outlined in red highlights the specific body part that is experiencing the greatest strain. The cabin’s interior, which is designed with male body dimensions in mind, significantly affects the female mineworker’s ability to operate the machine comfortably. Additionally, Figure 5 also shows that the worker must continually twist her neck while operating the machine, which can significantly increase the risk of neck strain and musculoskeletal injury.

Figure 6 presents the REBA for the female mineworker operating a shuttle car. Although her final REBA score was 7, classified as medium risk, it signals that further investigation is warranted and corrective actions should be implemented promptly.

Figure 7 and Figure 8 show a female mineworker hanging a CM cable. Figure 8 shows the height of the roof that the worker has to reach in order to hang the cable. The red circle highlights the regions experiencing strain.

Tasks such as lifting heavy materials or operating machinery in underground coal mining force female mineworkers to adopt awkward postures that can lead to injury. Figure 9 shows a female mineworker standing as she operates a roof-bolting machine. She must carry out bolting operations for roughly seven to eight hours, with only brief and infrequent rest intervals.

Table 2. REBA scoring for the second shuttle car operator, three roof bolt operator and a CM cable handler.

Sections of the Body	Shuttle Car 2	Roof Bolter 1	Roof Bolter 2	Roof Bolter 3	CM Cable Handler
Neck	2	2	2	2	2
Trunk	3	1	1	1	4
Leg	1	1	1	1	2
Trunk posture score	2	2	2	2	6
Force load	0	1	1	1	2
Posture + Force load	2	3	3	3	8
Upper arm	5	5	5	5	3
Lower arm	2	2	2	2	1
Wrist	3	2	2	2	2
Posture score	8	8	8	8	4
Coupling	1	2	2	2	3
Coupling score	9	10	10	10	7
Posture + Coupling score	6	8	8	8	10
Activity	1	1	1	1	1
REBA score	7	9	9	9	11

presents the REBA scores for the second shuttle car operator, three roof bolt operators, and the continuous miner (CM) cable handler. The results indicate that the shuttle car and roof bolt operators share identical scores, respectively. However, it is important to note that the REBA does not take into consideration other factors that contribute to ergonomic risk, such as machine vibration, and ground conditions which also add to ergonomic exposure of workers. The CM cable handler recorded a REBA score of 11, which is considered very high. This result suggests an urgent need for corrective action, as such a score indicates a significant risk of musculoskeletal strain, particularly lower back pain.

4. Discussions

The results of this study reveal substantial ergonomic challenges associated with underground coal mining, particularly concerning the absence of gender-inclusive design in mining equipment. Machinery such as roof bolters, shuttle cars, and LHD vehicles are predominantly designed according to male anthropometric parameters [25]. This design bias fails to accommodate the physical stature, strength, and postural requirements of female operators, thereby increasing their susceptibility to musculoskeletal disorders (MSDs). A postural study led by Eger et al. [26] in Canadian underground mines revealed that LHD operators spent more than 94% of their work time with their neck rotated over 40°, while loading and transporting materials. The visibility constraints of the LHD cabin affect both male and female operators, as the restricted cab design limits the field of view for all users. However, the degree of impact differs between men and women due to differences in body size, stature, and seating position. Female operators, who on average may have shorter stature and different eye height levels, could experience more severe visibility limitations, requiring greater postural adjustments (e.g., leaning or twisting) to see their work area. Therefore, while the visibility issue applies to both genders, its ergonomic consequences may be more pronounced for female operators.

The postural pictures presented in Figure 4 and Figure 5 demonstrate that female operators of shuttle cars frequently adopt non-neutral sitting positions due to restrictive cabin configurations. Such conditions elevate spinal load and accelerate the onset of lower back pain [27,28]. Additionally, the constant neck rotation required for visual monitoring, as observed in Figure 5, heightens the risk of cumulative musculoskeletal stress. The REBA score of 7 assigned to the female shuttle car operator (Figure 6) corresponds to a medium risk category; however, given the prolonged duration of exposure and constrained working conditions, this rating may underestimate the true ergonomic burden. A study conducted by Rao and Venkatesh [29] produced comparable results. It involved analyzing thirty drivers from Telangana, India, who had no prior musculoskeletal conditions. The researchers assessed the ergonomic risks linked to the drivers’ seating postures using the Rapid Entire Body Assessment (REBA) method. The findings showed that most drivers (90%) were classified in the medium-risk category, with REBA scores between 4 and 7, highlighting a clear need for ergonomic improvements. When the cabin does not accommodate workers’ anthropometric body dimensions, they may be forced to adopt awkward or improper postures, resulting in discomfort and potential musculoskeletal disorders. Additionally, the cabin design misalignment may increase the risk of trips, falls, and other hazardous situations, especially during emergencies when fast responses are crucial. Improper working posture can lead to musculoskeletal disorders, including pain in the back, neck, and shoulders. It may also result in ongoing joint and spinal discomfort, as well as long-term degenerative conditions.

Further ergonomic concerns emerge from tasks involving cable handling (Figure 7 and Figure 8). These activities often require female workers to lift or suspend heavy CM cables above shoulder height while maintaining balance on uneven surfaces. The combination of overhead reaching and high force exertion substantially increases biomechanical stress on the shoulders and lumbar region [30]. These activities pose immediate health risks such as sprains, strains, and back injuries, as well as long-term issues like chronic pain in the spine, shoulders, and joints due to repeated stress. Repeated exposure to heavy or awkwardly shaped loads can result in chronic musculoskeletal conditions, including carpal tunnel syndrome and disc disorders. Figure 9 illustrates another critical concern: prolonged static posture during roof-bolting operations. Female operators are required to remain standing for approximately seven to eight hours per shift, with minimal rest opportunities. Prolonged exposure to static postures is strongly associated with fatigue accumulation, intervertebral disc compression, and chronic musculoskeletal symptoms [26]. These findings suggest that current workstation designs are misaligned with the anthropometric diversity of the workforce and do not support sustained biomechanical efficiency. The REBA results presented in Table 2 further corroborate these observations. The identical scores recorded for shuttle car operators and roof bolt operators, respectively, suggest similar levels of ergonomic risk exposure across these operational categories. Of particular concern is the REBA score of 11 for the continuous miner (CM) cable handler, which denotes a very high-risk level. Such a result indicates a strong likelihood of lower back injury and underscores the necessity for immediate ergonomic intervention. Despite these challenges, structured breaks remain largely absent, rest breaks are either improvised or dependent on lenient supervisors, and fatigue management policies are rarely implemented in practice. Many female mineworkers eat on the move, endure entire shifts without formal rest, and work in ways that compromise physical well-being. Furthermore, female mineworkers are often expected to perform the same tasks as their male counterparts, despite differences in physical strength and endurance. Musculoskeletal disorders (MSDs) of mine workers such as backache and joint pains have somehow not received due attention, although they probably contribute to high morbidity and absenteeism.

The implementation of ergonomics principles during the design and manufacture of any article for use at a mine is mandated in the Mine Health and Safety Act (Act 29 of 1996) [31]. The goal of ergonomics is to ensure that tasks, jobs, products, machines, equipment, environments, and systems are suited to people to improve their health, safety, productivity, and well-being. Female mineworkers remain at risk of ergonomic hazards, and without proper systems in place to address these issues in underground coal mining, musculoskeletal disorders and back pain will likely continue to be prevalent. This paper aimed at highlighting the effect of inadequate ergonomics and poorly designed mining equipment on female workers, with findings indicating that current machineries are not appropriately configured to accommodate the anthropometric and postural needs of female mineworkers. Overall, the evidence highlights the urgent need to integrate gender sensitive and ergonomically adaptive design principles into mining machinery. Interventions should include adjustable seating systems, modify cabin space, optimized control panel placement, and vibration-dampening mechanisms. Moreover, task redesign, worker training, and rotation schedules could mitigate repetitive strain and reduce cumulative exposure. Beyond the immediate health implications, these findings emphasize that inclusive ergonomic design represents not only a safety imperative but also a strategic approach to improving productivity and job satisfaction.

5. The Authors Acknowledge the Following Limitations

Although this paper reports on a specific objective, it forms part of a larger, ongoing study. The current study focused exclusively on female mineworkers engaged in underground operations, such as machine handling and related activities. Male mineworkers were not included, as the study was not designed as a comparative analysis between genders. Due to the operational constraints of the mining industry, data collection had to be conducted within the limited time frame permitted by mine management. The researcher was not allowed to interrupt or halt production processes, which further restricted access. Additionally, underground mining environments are highly regulated, hazardous, and difficult to access, making it impractical to include a large number of participants. Given the homogeneity of the underground mining workforce, where workers often share similar conditions and experiences, a smaller sample was deemed sufficient to yield the desired results. Nevertheless, the study may have been affected by the reduced participation rate. A larger sample size could potentially have strengthened the findings and enhanced the robustness of the conclusions.

6. Conclusions

This study highlights the significant ergonomic risks faced by female mineworkers, particularly the elevated likelihood of developing musculoskeletal disorders (MSDs) due to prolonged exposure to awkward postures, repetitive motions, heavy lifting, and static or non-neutral body positions, as exemplified by the high REBA score of the CM machine cable handler. The findings suggest that cabin designs are not adequately suited to accommodate female mineworkers, and when combined with prolonged standing without adequate rest, these factors considerably increase the associated risks. Importantly, these challenges are intensified by the continued design of most mining equipment primarily for male operators, with little attention given to the anthropometric and ergonomic needs of female mineworkers. Addressing these issues requires proactive, gender sensitive design strategies that integrate the needs of female mineworkers from the outset, rather than expecting them to adapt to existing machinery. Promoting gender equity in mining is not only a matter of regulatory compliance but also essential for sustaining a safe and productive workforce as the industry continues to operate over the coming decades. The authors advocate for further research to explore the holistic ergonomic challenges faced by female mineworkers. Comparative studies between male and female operators are particularly warranted to identify differences in outcomes, behaviours, and risk exposures, thereby informing targeted interventions. Such research will provide actionable recommendations that enable the mining industry to protect its workforce while adhering to occupational health regulations.