Ensuring that respiratory protection is effective for all can be difficult if limited resources are available to assist with selecting a well-fitting respirator model and user guidance. To better understand how various N95® filtering facepiece respirator models fit on a variety of face sizes, a quantitative fit evaluation was performed on 12 different N95 respirators distributed by the Strategic National Stockpile using five manikin headform sizes representative of most of the U.S. worker population (540 total tests). Manikin fit factor results varied depending on the respirator model and headform combination. Four respirator models achieved passing fit results across all headform sizes. Predictive modeling was then initiated, where the headform most closely aligned to an individual's facial dimensions is determined and then used to identify N95 respirators that may provide an acceptable fit. A multinomial logistic regression model was trained and tested using NIOSH's 2003 Anthropometric U.S. Survey and was found to have an accuracy of 85%. To address potential risks associated with predicting only a single headform size, a modified model allowing for multiple headform size predictions was also assessed and found to have an improved accuracy rate of 98%. With further human subject validation and field testing, this modeling approach could be used as a tool to aid in making the fit testing process more efficient, less burdensome, and better enable individuals to use respirators that fit more effectively, thereby adequately protecting them from hazards.

Between 2018 and 2022, an average of 21,955 fireground injuries occurred annually in the United States [1]. Among these, thermal burns were one of the most common injuries, accounting for approximately 10% of fireground incidents [1]. This underscores the urgent need to improve turnout gear technology to provide better thermal protection for firefighters. Phase change materials (PCMs) can absorb substantial amounts of latent heat during the melting process while maintaining a constant temperature, which makes them ideal for enhancing thermal protection. Our proposal aims to leverage this protective property integrating PCM segments into turnout gear to improve its thermal protective performance (TPP). This study involves numerical simulations, which will serve as a foundation for future experimental designs and testing protocols. While existing numerical studies on fire protective clothing typically utilize one-dimensional (1D) models [2], there is a lack of comprehensive three-dimensional (3D) models that are capable of assessing the overall thermal performance of turnout gear on the human body. The goal is to determine the optimal PCM melting temperature range for turnout gear, maximizing thermal protection for firefighters. MethodWe conducted 3D heat transfer simulations using COMSOL Multiphysics (COMSOL, Inc., Burlington, MA 01803, USA). To accommodate firefighters' movements and activities in fire scenes, PCM was broken into multiple segments covering the main body while avoiding joints. The bioheat transfer module was utilized to model the human body's thermal regulation. The equivalent heat capacity method was employed to simulate the phase change process. Adhering to the guidelines of the National Fire Protection Association (NFPA 1971, Standard on Protective Ensembles for Structural Fire Fighting and Proximity Fire Fighting), heat fluxes of 83 kW/m2 and 8.3 kW/m2 were applied to the outer surface of turnout gear to replicate flashover and hazardous conditions, respectively [3,4]. These heat fluxes represented the radiant/convective heat sources in fire scenes. The 3.0-mm-thick PCM segments were utilized based on the prior research by our team [5]. We investigated the effects of different melting points of PCMs at various locations in clothing fabrics on the thermal protection behavior of PCM-integrated turnout gear. PCM melting points in the range of 40°C-200°C were evaluated. Three PCM locations-1 mm, 2 mm, and 3 mm beneath the outer shell surface-were investigated to explore the effect of PCM location on the optimum melting temperaturesResultsResults show that a PCM melting temperature range of 50°C-70°C provides optimal protection for the human body, extending the time it takes to reach second-degree burns from 18 seconds to approximately 45 seconds. This range is particularly effective because it aligns with the threshold for second-degree burns (approximately 60°C), helping to maintain skin temperature at or below 60°C for extended periods during fire exposure, thereby reducing the risk of severe burn injuries. Additionally, positioning the PCM closer to the inner surface of the clothing enhances its thermal protective performance.ConclusionIncorporating PCM segments with melting point of 50°C-70°C into firefighter turnout gear could increase the time it takes for skin to reach the threshold for second-degree burns by around 1.5 to 3 times, compared to traditional gear without PCM technology. The insights gained from 3D modeling provide a valuable foundation for developing next-generation turnout gear for firefighters.DisclaimerThe findings and conclusions in this abstract are those of the authors and do not necessarily represent the official position of the National Institute for Occupational Safety and Health (NIOSH), Centers for Disease Control and Prevention (CDC). Mention of any company or product does not constitute endorsement by NIOSH, CDC.References[1] Campbell, R. Firefighter Injuries on the Fireground. NFPA Research, July 2024. Available from: https://www.nfpa.org/education-and-research/research/nfpa-research/fire-statistical-reports/patterns-of-firefighter-fireground-injuries[2] Fonseca, A., Neves, S.F., Campos, J.B.L.M., 2021. Thermal performance of a PCM firefighting suit considering transient periods of fire exposure, post-fire exposure and resting phases. Applied Thermal Engineering 182, 115769.[3] NFPA 1971, Standard on Protective Ensembles for Structural Fire Fighting and Proximity Fire Fighting, 2018.[4] Coletta, G.C., Arons, I.J., Ashley, L.E., Drennan, A.P.,1976. The Development of Criteria for Firefighters' Gloves Volume II: Glove Criteria and Test Methods. Contract No. CDC-99-74-59, February 1976.

Phase change materials (PCMs) are extensively utilized in thermal management applications. We examined thermal protection enhancement in structural firefighting gloves through the incorporation of PCMs, particularly under conditions influenced by moisture from hand sweating or external water sources. We conducted experiments to assess the impact of varying moisture content (MC) levels within glove fabrics on the temperature regulation performance of PCM-integrated firefighters' gloves. Three scenarios in fire settings were considered in the study, including contact with hot surfaces (conductive heat) and exposure to hazardous environments and flashovers (radiant/convective heat sources). Our findings indicate that under intense heat, the time before reaching a second-degree burn threshold (60 degrees C) on hand skin surface was minimized at lower MC levels. However, when the MC level exceeded specific values, the duration of thermal protection increased with higher moisture levels. The PCM integration extended thermal protection by between 1.4 and 2.1 times during direct contact tests and by between 1.2 and 1.5 times under radiant/convective heat exposures, compared to non-PCM gloves under similar wet conditions. Additionally, PCM layer's release of latent heat during solidification led to a prolonged temperature rise on skin surface at post-exposure, while moisture assisted in enhancing the thermal dissipation rate following heat exposure due to effective water evaporation.

Filtering facepiece respirators (FFRs) are manufactured in discrete sizes, with some models being limited in accommodating the fit of some sex and race combinations. This study presents the development of a custom-fit respiratory protective device (RPD) which conforms to a user's facial features and flexes and moves with facial movements during use. Our design also integrates a pressure-sensing network, which continuously monitors fit and will alert the user when the fit is compromised. In this Part II of the three-part series, we design and incorporate a continuous fit monitoring system in the RPD designed in Part I to enhance its role in protecting users from inhalation hazards in an effective manner during its use. The fit monitoring system comprises a fabric-based sensor network integrated into the RPD and an Android-based App designed to alert the user when the pressure at the faceseal falls below a given threshold established during the initial configuration of the RPD for the user. We also develop algorithms for the incorporation of the sensor slots and data buses into the custom-fit RPD using the Taxonomy of Landmarks defined in Part I. We enhance the structure developed in Part I to secure the sensor network during the use of the RPD. We develop algorithms for customizing a fastening hub to suit the head profiles of individuals to enable them to don the RPD quickly, easily, effectively, and in a repeatable manner. We demonstrate the successful application of the total design methodology by creating digital prototypes for three individuals with different facial profiles and make further advances to our goal of ensuring equitable respiratory protection for all including children, for whom RPDs are currently limited.

Firefighters often work under dangerous and harmful conditions, which could cause unexpected accidents, injuries, and deaths. There were 19,200 injuries that occurred on the fireground in the United States in the year 2021, and more than 10% of these injuries were caused by burns and thermal stress [1]. The current NFPA 1971 (Standard on Protective Ensembles for Structural Fire Fighting and Proximity Fire Fighting) requests that firefighters’ turnout gear textiles meet the minimum requirement of a thermal protective performance (TPP) rating of 35, equating to 17.5 seconds until second-degree burns occur in a flashover situation [2]. Notably, exposure to a high-temperature environment could be much longer than a few seconds when firefighters conduct rescue tasks at a fire scene. Hence, research is needed to explore novel turnout gear technology that can significantly enhance thermal protection for firefighters. Phase change materials (PCMs) can absorb large amounts of latent heat while maintaining a constant melting temperature. We use this phenomenon to incorporate PCM into turnout gear to enhance the TPP. Numerical simulations were performed in this work which can guide future experimental design and testing to save time and effort. Currently, a three-dimensional (3D) turnout gear-equipped human thermal model is unavailable. Therefore, this work is the first 3D numerical study to explore (1) the thermal protection improvements of firefighters’ turnout gear by using PCM segments under flashover/explosive and hazardous conditions, and (2) the minimum amount of PCM required to enhance the thermal protection without significantly increasing the weight of firefighters’ turnout gear. Methods3D heat transfer simulations were performed through COMSOL Multiphysics (COMSOL, Inc., Burlington, MA 01803, USA). To maintain firefighters’ activities and movements in the fire scene, PCM was broken down into several segments to cover the main body but avoid joints. The blood circulation effect in the body was considered as a bioheat source in the model. The equivalent heat capacity method was used to simulate the phase-changing process. The heat flux applied at the outer surface of turnout gear (mimicking combined radiant and convective heat sources at the fire scene) was 83 kW/m2 for flashover/explosive conditions and 8.3 kW/m2 for typical hazardous conditions according to the current NFPA 1971 standard [2,3]. Various PCM segment thicknesses were studied to determine the minimum amount of PCM required to achieve sufficient thermal protection.ResultsThis study found that the 3.0-mm-thick PCM segments with a melting temperature of 60°C can extend the time for the skin surface to reach second-degree burn injury (60°C [3]) by 18 seconds and 52 seconds under flashover/explosive and hazardous conditions, respectively. Moreover, thinner PCM segments, i.e., 1.0-3.0 mm thickness, could also remarkably mitigate the temperature increase on the skin surface while reducing the added weight of turnout gear.ConclusionThe PCM segments could increase the time for the skin surface to reach second-degree burn injury by around 2.0 times compared to conventional firefighters’ turnout gear with no PCM. The 3D modeling results can be used to develop a next-generation firefighter turnout gear technology. DisclaimerThe findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the National Institute for Occupational Safety and Health (NIOSH), Centers for Disease Control and Prevention (CDC). References[1] Campbell, R., Hall, S., United States firefighter injuries in 2021, NFPA Res. December 2022. [2] NFPA 1971, Standard on Protective Ensembles for Structural Fire Fighting and Proximity Fire Fighting, 2018.[3] Coletta, G.C., Arons, I.J., Ashley, L.E., Drennan, A.P., 1976. The Development of Criteria for Firefighters' Gloves Volume II: Glove Criteria and Test Methods, Contract No. CDC-99-74-59, February 1976.

Some respiratory protective devices (RPDs) such as filtering facepiece respirators (FFRs) are manufactured in discrete sizes, with some models being limited in accommodating the fit of some gender and race combinations. This study presents the development of a custom-fit RPD which conforms to a user’s facial features and flexes and moves with facial movements during use. Our design also integrates a pressure-sensing network, which continuously monitors fit and will alert the user when the fit is compromised. In this final part of the three-part series, we transform the digital prototypes of the custom-fit RPD presented in Parts I and II to physical prototypes through 3D printing (additive manufacturing) using silicone-based elastomers. We identify the key material properties required for creating the physical prototypes. Based on a comparative analysis of commercially available materials, we select two of them and create prototypes of the RPD using two different commercial 3D printers. We then demonstrate the responsiveness of the custom-fit RPD to changes in facial profile during use from natural (neutral facial expression with mouth closed) to talking, to smiling, and to yawning, and the quantification of the changes in pressure at the faceseal by the continuous fit monitoring system through an App running on an Android tablet. With the realization of the successful custom-fit RPDs using the developed methodology, we lay the foundation for providing respiratory protection, and improved source control, to the full spectrum of individuals in the United States public including children, for whom FFRs options are currently limited.

Phase change material (PCM) has been widely studied for efficient thermal management. This work is the first holistic experimental research on the temperature control performance of PCM-integrated firefighters' gloves. The results showed that the thermal protection time could be extended by 2-5 times in the direct contact to hot object tests and around 1.5 times under the radiant/convective heat source tests when embedding a 1-mm-thick PCM layer in gloves. The PCM of melting point 68 °C showed the best thermal protection performance in all test conditions since it had the most efficient phase change function during the heating process. Considering the PCM location effect, the PCM with lower melting point (68 °C) showed better performance when located close to external environment (heat source) and the PCM with higher melting point (108 °C and 151 °C) showed better performance when located close to hand. The optimum PCM thickness would be in the range of 0.5-1.0 mm for both thermal protection improvement and hand dexterity purposes. In addition, the time for continuous temperature rises on the hand surface at post-heat exposure was longer when embedding PCM in firefighters’ gloves due to the stored latent heat in PCM.

In 2022, approximately 65,650 firefighter injuries were recorded on duty, marking an 8% rise from the 2021 tally of 60,750 injuries [1]. The majority of these injuries took place during fireground operations, with burns and thermal stress accounting for about 15% of such incidents [1]. Given this problem,a pressing need exists to advance turnout gear technology for better thermal protection for firefighters. Our proposal involves integrating phase change material (PCM) into firefighters' turnout gear to enhance its protective capabilities through utilizing the large amounts of latent heat of fusion. Our study involves numerical simulations, serving as a guide for future experimental designs and testing protocols to streamline efforts and time investment. Notably, existing numerical investigations on fire protective clothing predominantly employ one-dimensional (1D) models [2], lacking a comprehensive three-dimensional (3D) turnout gear-equipped human thermal model to assess the overall thermal performance of turnout gear on the body. Therefore, our study represents a pioneering effort, being the first 3D numerical analysis aimed at determining the optimal dimensions of PCM and strategically placing PCM segments within the turnout gear to maximize thermal protection coverage while minimizing the PCM quantity required. MethodsWe conducted 3D heat transfer simulations using COMSOL Multiphysics (COMSOL, Inc., Burlington, MA 01803, USA). To accommodate firefighters' movements and activities in fire scenes, PCM was divided into multiple segments covering the main body while avoiding joints to maintain firefighter body movement and activities. The bioheat transfer module in COMSOL was utilized to model the human body's thermal regulation. The equivalent heat capacity method was employed to simulate the phase change process. Adhering to the guidelines of the National Fire Protection Association (NFPA 1971), Standard on Protective Ensembles for Structural Fire Fighting and Proximity Fire Fighting [3], heat fluxes of 83 kW/m2 and 8.3 kW/m2 were applied to the outer surface of turnout gear to replicate flashover and hazardous conditions, respectively [4]. These heat fluxes represented the radiant/convective heat sources in fire scenarios. Utilizing 3.0-mm-thick PCM segments with a melting temperature of 60°C, as established in prior research by our team [5], we investigated three different sizes of PCM segments and their corresponding distributions within the turnout gear. These sizes included small (1"-2") segments ranging from 4 to 12 pieces, medium (2"-4") segments with 2 to 6 pieces, and large (4"-6") segments with 1 to 2 pieces distributed in each thermal zone of the human body. Using a larger number of small PCM segments can maintain the same latent heat capacity as the large PCM segments but have more efficient heat absorption.ResultsThe size of PCM segments did not significantly affect the thermal protection time as long as there were enough PCM segments to cover the area. These segments proved effective in reducing temperature increases in areas not directly shielded by PCM segments during periods of intense heat.ConclusionThis computational study has demonstrated that the segment size of PCM has minimal impact on the overall thermal protection efficacy of PCM-integrated firefighters’ turnout gear, provided there is sufficient coverage of PCM pieces within the gear. However, smaller PCM segments are recommended for enhanced flexibility and comfort in firefighters’ turnout gear. The findings from 3D modeling can serve as a foundation for the advancement of next-generation firefighter turnout gear.DisclaimerThe findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the National Institute for Occupational Safety and Health (NIOSH), Centers for Disease Control and Prevention (CDC). Mention of any company or product does not constitute endorsement by the NIOSH, CDC

Transient three-dimensional (3D) heat and moisture transfer simulations were conducted to analyze the thermal performances of the entire phase change material (PCM) integrated into firefighters' gloves. PCM was broken down into several segments to cover the back and palm of the hand but to avoid finger joints to keep hand functions. Parametric studies were performed to explore the effects of PCM melting temperatures, PCM locations in the glove and PCM layer thicknesses on the overall thermal performance improvement of firefighters' gloves. The study found that PCM segments could extend the time for hand skin surfaces (areas covered or not covered by PCM) to reach second-degree burn injury (60 °C) by 1.5-2 times compared to conventional firefighters' gloves without PCM. Moreover, PCM segments could help mitigate the temperature increase on hand skin and glove surface after fire exposure.

Injuries associated with hands and fingers are highly prevalent in mining and identifying factors associated with these injuries are critical in developing prevention efforts. This study identifies nonfatal injury incidence rates, nature of injury, work activities, glove usage, and sources of hand and finger injuries in the U.S. mining industry, as reported to the Mine Safety and Health Administration (MSHA) from 2011 - 2017. Hand and finger injuries occur at a rate of 6.53 per 1000 full-time employees, which is nearly double the rate of the next highest affected body part, the back. Most of the hand and finger injuries were classified as cuts/lacerations/punctures (53%) followed by bone fractures/chips (26%). Materials handling and maintenance/repair were common activities at the time of the incident with miscellaneous metals (pipe, wire, guarding) and hand tools as the primary sources of hand and finger injury. Although the information on glove use was limited, leather gloves were most often worn when an injury occurred. When worn, gloves were found to contribute to 20% of the injuries, indicating their potential to protect the hands, but also potentially put the hands at risk. Further research is necessary to determine performance requirements for gloves used in mining operations, specifically those offering cut and puncture resistance.

Firefighter injures caused by burns and thermal stress occupies around 5%-10% of the total injuries annually. Glove is the thinnest/weakest components among the firefighter turnout gear, which can put firefighters, are at risk of severe wrist and hand burns during fire calls. Burns can occur quickly and enhancing the thermal protective performance of firefighters' gloves will prevent these burns. One-dimensional (1D) heat transfer modeling and simulations were performed through the COMSOL Multiphysics software to investigate the improvement of thermal protective performance when integrating a Phase Change Material (PCM) layer into a conventional structural firefighting glove. Parametric studies were conducted to explore the effects of PCM thermal properties, layer thickness, and location in glove structure on hand protection. It was found that a PCM with a higher density, specific heat, and latent heat of fusion had a larger heat capacity and thermal inertia, resulting in better thermal protective performance. The optimum melting point of PCM was found to be in the range of 80°C-140°C. A PCM layer with a thickness of 0.5 mm-1.0 mm showed sufficient thermal protection. The location of the PCM layer should be close to the inner glove surface for high-heat situations. Overall, modeling suggests that the addition of a PCM layer could significantly enhance the thermal protective performance of firefighters' gloves, with results showing increased time (2-4 times as long) for skin to reach second-degree burn temperature when compared to the conventional glove without PCM.

Slips, trips, and falls (STFs) are the second leading cause of non-fatal injuries and can lead to fatal incidents in the mining industry. Hazard identification is an essential first step in remediating STF hazards and creating a safer work environment. Previous research has identified industry-specific risk factors for STFs, evaluated exposures to those risk factors, and developed taxonomies of the hazards for the construction and farming sectors. In comparison, ErgoMine-a mobile device application-based ergonomics audit tool-is the only systematic evaluation tool that covers STF hazards in the mining industry. However, ErgoMine was not specifically developed to address STF hazards. This paper describes the development of a taxonomy that helps identify STF hazards at surface mining sites and provides recommendations to address these hazards to inform future evaluation tools. The objective was to develop a taxonomy that was self-explanatory, observable, repeatable, and solution oriented. In addition to current regulations, standards and guidelines were used to develop the taxonomy to ensure the focus was beyond basic compliance. A detailed description of how the STF hazard taxonomy was created for walkways, stairways, and fixed ladders is provided, along with two specific applications of its use. The STF hazard taxonomy can be used to develop tools like checklists and ergonomics audits to identify and remediate slip, trip, and fall hazards at surface mining facilities, thereby improving worker safety.

Material handling injuries reported to the U.S. Mine Safety and Health Administration (MSHA) result in nearly 70,000 days of work lost each year. Several mitigation efforts for these injuries focus on the back, but shoulder injuries account for four times the days lost. Nonfatal incidents reported to MSHA from 2013 through 2017 were limited to shoulder sprains and strains and were analyzed to determine what contributed the most to these injuries. Injuries were coded based on the task performed, motions involved, and the tools used. The analysis indicated that auto maintenance and tasks involving loading/unloading supplies led to the highest number of injuries. Many of these injuries were related to operating equipment or the use of specific tools. The injuries often involved lifting/lowering or pulling/pushing movements. These findings suggest future mitigation strategies for the risk of shoulder sprains and strains should focus on auto maintenance and tasks involving loading/unloading supplies.

Improving mine worker safety and health is a key goal for the Pittsburgh Mining Research Division of the National Institute for Occupational Safety and Health (NIOSH). Opportunities to enhance the safety and health of mobile mining equipment operators through strategies to lower the risk of musculoskeletal disorders and traumatic injuries is an important element of the overall NIOSH mining research program. This paper reviews various emerging technologies that, if fully developed and implemented, could positively impact the health and safety of mine workers who operate mobile mining equipment. Those technologies showing potential for enhancing operator safety and health in the near future are addressed herein.

During a public health emergency, respirator shortages can have a profound impact on the national response, such as for the current coronavirus disease 2019 (COVID-19) pandemic. Due to a severe shortage of respirators (particularly filtering facepiece respirators [FFRs]), there may be contexts in which understanding the performance of FFRs that are approved for use as part of a crisis capacity strategy is desired. This includes FFRs that are not covered under the National Institute for Occupational Safety and Health (NIOSH) Respirator Approval Program because they have been stored past their designated shelf life, have been decontaminated, or are approved by international certification bodies other than NIOSH. The purpose of this document is to provide a general framework to assess the performance of FFRs that are only being used as a crisis capacity strategy. The intended audience are those who are responsible for managing large amounts of FFRs. This framework includes a four-step process consisting of: 1) defining the population of FFRs to be sampled; 2) providing sampling strategy options; 3) inspecting and testing the sampled units; and 4) evaluating the results. In addition to the four-step process, we provide an example of how NIOSH recently evaluated the quality of FFRs sampled from ten U.S. stockpiles.

Footwear plays an important role in worker safety. Work boots with safety toes are often utilized at mine sites to protect workers from hazards. Increasingly, mining operations require metatarsal guards in addition to safety toe protection in boots. While these guards provide additional protection, the impact of metatarsal guards on gait are unknown. This study aimed to measure the effects of 4 safety work boots, steel toe, and steel toe with metatarsal protection in wader- and hiker-style boots, on level and inclined walking gait characteristics, during ascent and descent. A total of 10 participants completed this study. A motion capture system measured kinematics that allowed for the calculation of key gait parameters. Results indicated that gait parameters changed due to incline, similar to previous literature. Wader-style work boots reduced ankle range of motion when ascending an incline. Hip, knee, and ankle ranges of motion were also reduced during descent for this style of boot. Wader-style boots with metatarsal guards led to the smallest ankle range of motion when descending an inclined walkway. From these results, it is likely that boot style affects gait parameters and may impact a miner's risk for slips, trips, or falls.

Within the metal/nonmetal mining sector, fall-related incidents account for a large proportion of fatal and non-fatal injuries. However, the events and contributing factors leading up to these incidents have not been fully investigated. To help provide a clearer picture of these factors, an analysis of imminent danger orders issued by the Mine Safety and Health Administration (MSHA) between 2010 and 2017 at both surface and underground metal/nonmetal mine sites revealed that most orders are associated with fall risks. Of these cases, 84% involved the workers not using fall protection, fall protection not being provided, or the improper use of fall protection. Fall risks for workers most frequently occurred when standing on mobile equipment, performing maintenance and repairs on plant equipment, or working near highwalls. In most cases, a single, basic, corrective action (e.g., using fall protection) would have allowed workers to perform the task safely. Overall, these findings suggest that a systematic approach is needed to identify, eliminate, and prevent imminent danger situations. Furthermore, to protect mineworkers from falls from height, frequently performed tasks requiring fall protection should be redesigned to eliminate the reliance on personal fall protection.

Slips, trips, and falls (STF) contribute significantly to nonfatal incidents at surface mines. Although fall fatalities and STF from mobile equipment have been investigated, nonfatal incidents and STF hazards encountered at mines are not well documented. This paper aims to identify occupations and activities associated with nonfatal STF incidents at surface stone, sand, and gravel mines, document through a systematic observation the STF hazards encountered, and corroborate the findings of the hazard assessment using an analysis of nonfatal injury narratives reported in the Mine Safety and Health Administration (MSHA) injury database. Mobile equipment operators, laborers/utility men, and mechanics were most often involved in nonfatal STF incidents. Walking/running, getting on/off equipment, machine maintenance and repair, and handling supplies and materials accounted for over 80% of the activities being performed at the time of the incident. Solid debris, in the form of rocks and stones on unpaved surfaces and material accumulation on paved surfaces, and liquid contaminants, primarily pooled water, were common hazards identified during the systematic observation. Stair tread issues and transitions to and from ladders were also identified as hazards. These findings were in line with injury data where rocks, ice/snow, uneven ground, water, hoses, mud, and loose/unstable material were the most common contaminants and hazards encountered at the time of the incident. In addition, several recommendations are provided to help eliminate or remediate the identified hazards.

A large proportion of non-fatal slips, trips, and falls (STFs) at surface mining facilities are associated with mobile equipment. Ingress and egress from mobile equipment can pose a fall risk to mobile equipment operators. The objective of this study was to determine mobile equipment operators' views of STF risks from mobile equipment, and to ascertain what factors, tasks, and conditions they perceive as contributing to these risks. A thematic analysis of 23 individual interviews and 2 group interviews was conducted, with 10 overarching themes identified from the transcripts. Mobile equipment operators indicated that being unable to see their feet or the ladder rungs during descent and the presence of contaminants on the ladders caused by normal operation make egress more dangerous than ingress. The flexible rails and high heights of the lower rungs identified over 40 years ago as issues for mobile equipment operators still pose a perceived STF risk. Further, the requirements of routine maintenance tasks such as oil and filter changes, greasing, and cleaning windows pose fall risks due to inadequate access and the need to carry supplies up and down equipment ladders. In addition to the mobile equipment, hazardous ground conditions and insufficient lighting were found to be key issues around the mobile equipment and in parking areas. The findings of this work indicate that mobile equipment operators feel at risk for STFs due to the design and condition of their equipment, and would like to see ladders replaced with safer stairways as the primary ingress/egress system.