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PURPOSE: We investigated the influence of passive arm-support exoskeleton (ASE) with different levels of torque (50, 75, and 100%) on upper arm osteokinematics. METHODS: Twenty participants completed a cyclic overhead drilling task with and without ASE. Task duration, joint angles, and angular acceleration peaks were analyzed during ascent and descent phases of the dominant upper arm. RESULTS: Maximum ASE torque was associated with decreased peak acceleration during ascent (32.2%; SD 17.8; p < 0.001) and descent phases (38.8%; SD 17.8; p < 0.001). Task duration remained consistent. Increased torque led to a more flexed (7.2°; SD 5.5; p > 0.001) and internally rotated arm posture (17.6°; SD 12.1; p < 0.001), with minimal changes in arm abduction. CONCLUSION: The small arm accelerations and changes in osteokinematics we observed, support the use of this ASE, even while performing overhead cyclic tasks with the highest level of support.
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Work-related musculoskeletal disorders (WMSDs) are a major health concern in the construction industry. Occupational exoskeletons (EXOs) are a promising ergonomic intervention to help reduce WMSD risk. Their adoption, however, has been low in construction. To understand the contributing factors to EXO use-intention and assist in future decision-making, we built decision trees to predict responses to each of three EXO use-intention questions (Try, Voluntary Use, and Behavioural Intention), using online survey responses. Variable selection and hyperparameter tuning were used respectively to reduce the number of potential predictors and improve prediction performance. The importance of variables in each final tree was calculated to understand which variables had a greater influence. The final trees had moderate prediction performance. The root node of each tree included EXOs becoming standard equipment, fatigue reduction, or performance increase. Important variables were found to be quite specific to different decision trees. Practical implications of the findings are discussed.Practitioner summary: This study used decision trees to identify key factors influencing the use-intention of occupational exoskeletons (EXOs) in construction, using online survey data. Key factors identified included EXOs becoming standard equipment, fatigue reduction, and performance improvement. Final trees provide intuitive visual representations of the decision-making process for workers to use EXOs.
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This study explores the integration of Wide Field Optical Coherence Tomography (WF-OCT) with an AI-driven clinical decision support system, with the goal of enhancing productivity and decision making in breast cancer surgery margin assessment. A computationally efficient convolutional neural network (CNN)-based binary classifier is developed using 585 WF-OCT margin scans from 151 subjects. The CNN model swiftly identifies suspicious areas within margins with an on-device inference time of approximately 10 ms for a 420 × 2400 image. In independent testing on 155 pathology-confirmed margins, including 31 positive margins from 29 patients, the classifier achieved an AUROC of 0.976, a sensitivity of 0.93, and a specificity of 0.98. At the margin level, the deep learning model accurately identified 96.8% of pathology-positive margins. These results highlight the clinical viability of AI-enhanced margin visualization using WF-OCT in breast cancer surgery and its potential to decrease reoperation rates due to residual tumors.
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OBJECTIVE: The aim was to systematically evaluate the usability of all public electric vehicles (EV) direct current fast chargers (DCFC) in the San Francisco region. BACKGROUND: To achieve a rapid transition to EVs, a highly reliable and easy to use charging infrastructure is critical to building confidence among consumers. METHODS: The functionality and usability of all 182 open, public DCFC charging stations with CCS connectors (combined charging system) in the 9 counties of the Bay Area were tested (655 electric vehicle service equipment (EVSE) ports). An EVSE was classified as functional if it charged an EV for 2 minutes. RESULTS: Overall, 73.3% of the 655 EVSEs were functional. The causes of the nonfunctioning EVSEs (23.5%) were blank or unresponsive screens or error messages; payment system failures; charge initiation failures; network failures; or broken connectors. In addition, the cable was too short to reach the EV inlet for 3.2% of the EVSEs. A random sampling of 10% of the EVSEs, approximately 8 days after the first evaluation, found no overall change in functionality. CONCLUSIONS: The level of functionality found with field testing conflicts with the 95-98% uptime reported by the EV service providers (EVSPs) who operate the EV charging stations. There is a need for precise and verifiable definitions of uptime, downtime, and excluded time, as applied to public EV chargers. APPLICATION: The level of failure of the existing public EV DCFC charge infrastructure highlights the importance of improving the system design and maintenance to improve adoption of EVs.
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Observer, manual single-frame video, and automated computer vision measures of the Hand Activity Level (HAL) were compared. HAL can be measured three ways: (1) observer rating (HALO), (2) calculated from single-frame multimedia video task analysis for measuring frequency (F) and duty cycle (D) (HALF), or (3) from automated computer vision (HALC). This study analysed videos collected from three prospective cohort studies to ascertain HALO, HALF, and HALC for 419 industrial videos. Although the differences for the three methods were relatively small on average (<1), they were statistically significant (p < .001). A difference between the HALC and HALF ratings within ±1 point on the HAL scale was the most consistent, where more than two thirds (68%) of all the cases were within that range and had a linear regression through the mean coefficient of 1.03 (R2 = 0.89). The results suggest that the computer vision methodology yields comparable results as single-frame video analysis.Practitioner summary: The ACGIH Hand Activity Level (HAL) was obtained for 419 industrial tasks using three methods: observation, calculated using single-frame video analysis and computer vision. The computer vision methodology produced results that were comparable to single-frame video analysis.
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Mano , Análisis y Desempeño de Tareas , Humanos , Estudios Prospectivos , Extremidad Superior , Computadores , Grabación en Video/métodosRESUMEN
OBJECTIVE: The aim of this study was to estimate associations between biomechanical exposures and workplace neck and shoulder musculoskeletal disorders (NSMSDs) in a prospective cohort. METHODS: Manufacturing workers (N = 349) were followed for 28 months. Biomechanical exposures were collected on each individual, and physical examinations were performed every 4 months. Prevalent cases at baseline (n = 30) were excluded from the analysis. RESULTS: There were 18 incident cases of NSMSDs. Greater than 33% time in forceful hand exertion doubled the rate of incident NSMSDs. Greater than 18 degrees of shoulder abduction, during forceful hand exertion, increased the rate by 55%. Confidence intervals were wide. CONCLUSIONS: Effect estimates of the relationship between forceful hand exertions and NSMSDs were consistently elevated whether measured in isolation or while in shoulder abduction. Following a larger cohort with more frequent physical examinations would improve estimates of the model.
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Enfermedades Musculoesqueléticas , Enfermedades Profesionales , Humanos , Enfermedades Musculoesqueléticas/epidemiología , Enfermedades Profesionales/epidemiología , Esfuerzo Físico , Estudios Prospectivos , Factores de Riesgo , HombroRESUMEN
BACKGROUND: Although recent studies have identified important risk factors associated with incident carpal tunnel syndrome (CTS), risk factors associated with its severity have not been well explored. OBJECTIVE: To examine the associations between personal, workplace psychosocial and biomechanical factors and incident work disability among workers with CTS. METHODS: Between 2001 and 2010 five research groups conducted coordinated prospective studies of CTS and related work disability among US workers from various industries. Workers with prevalent or incident CTS (N=372) were followed for up to 6.4 years. Incident work disability was measured as: (1) change in work pace or work quality, (2) lost time or (3) job change following the development of CTS. Psychosocial factors were assessed by questionnaire. Biomechanical exposures were assessed by observation and measurements and included force, repetition, duty cycle and posture. HRs were estimated using Cox models. RESULTS: Disability incidence rates per 100 person-years were 33.2 for changes in work pace or quality, 16.3 for lost time and 20.0 for job change. There was a near doubling of risk for job change among those in the upper tertile of the Hand Activity Level Scale (HR 2.17; 95% CI 1.17 to 4.01), total repetition rate (HR 1.75; 95% CI 1.02 to 3.02), % time spent in all hand exertions (HR 2.20; 95% CI 1.21 to 4.01) and a sixfold increase for high job strain. Sensitivity analyses indicated attenuation due to inclusion of the prevalent CTS cases. CONCLUSION: Personal, biomechanical and psychosocial job factors predicted CTS-related disability. Results suggest that prevention of severe disability requires a reduction of both biomechanical and organisational work stressors.
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Síndrome del Túnel Carpiano , Enfermedades Profesionales , Síndrome del Túnel Carpiano/epidemiología , Síndrome del Túnel Carpiano/etiología , Humanos , Enfermedades Profesionales/epidemiología , Enfermedades Profesionales/etiología , Enfermedades Profesionales/prevención & control , Estudios Prospectivos , Factores de Riesgo , Lugar de Trabajo/psicologíaRESUMEN
There is a need for design criteria for above-shoulder work to prevent shoulder fatigue and supraspinatus injuries. A tool is developed to estimate maximum acceptable manual arm forces for above-shoulder work based on 25th % female strength with adjustments for supraspinatus tendon impingement and shoulder fatigue. The tool equations are presented along with tables of maximum acceptable manual arm forces in 77 locations in the 3 D space above the shoulder that accommodates a 50th % female reach. The largest acceptable anterior force, 140.3 N, occurs at shoulder height, 0.5 m anterior to the shoulder. The largest acceptable superior force, 84.4 N, occurs at shoulder height, 0.1 m anterior and 0.2 m medial to the shoulder. The new tool provides design criteria for arm exertions at a higher level of detail than prior ergonomic tools, making it useful for engineers. Based on sensitivity analyses, the tool is robust to parameter assumptions. Practitioner summary: Above-shoulder work is associated with increased risk for shoulder fatigue and injuries. A new tool is developed that estimates maximum acceptable manual arm forces for work at or above shoulder height. The tool can be used to design acceptable above-shoulder work so that it can be accomplished by most workers. Abbreviations: AFF: arm force field; AP: anterior/posterior; DC: duty cycle; GH: glenohumeral angle; HT: humerothoracic angle; LM: lateral/medial; MAE: maximum acceptable effort; MAF: maximum acceptable force; MAS: manual arm strength; MVC: maximum voluntary contraction; N: newton; OCRA: occupational repetitive action; R: reach distance; RMS: root means square; RULA: rapid upper limb assessment; SF: scale factor; SI: superior/inferior; ST: scapulothoracic angle; T: thoracicKEY POINTSA new design tool is introduced that estimates maximum acceptable hand forces for specific locations above the shoulder.This above-shoulder tool is based on a 50th percentile female anthropometry and 25th percentile female manual arm strength.These base strengths are multiplied by scaling factors that adjust for subacromial impingement and fatigue.The tool was shown to be robust based on sensitivity analysis.
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Articulación del Hombro , Hombro , Brazo , Fenómenos Biomecánicos , Fatiga , Femenino , Humanos , Masculino , Manguito de los RotadoresRESUMEN
BACKGROUND: International consensus is needed on case definitions of work-related musculoskeletal disorders and diseases (MSDs) for use in epidemiological research. We aim to: 1) study what information is needed for the case definition of work-related low back pain (LBP), lumbosacral radicular syndrome (LRS), subacromial pain syndrome (SAPS), carpal tunnel syndrome (CTS), lateral and medial elbow tendinopathy, and knee and hip osteoarthritis, and to 2) seek consensus among occupational health professionals/researchers regarding the case definitions of these work-related MSDs. METHODS: A two-round Delphi study was conducted with occupational health professionals/researchers from 24 countries. Definition of work-related MSDs were composed of a case definition with work exposures. Round 1 included 32 case definitions and round 2, 60 case definitions. After two rounds, consensus required 75% of the panellists to rate a case definition including work exposures ≥7 points on a 9-point rating scale (completely disagree/completely agree). RESULTS: Fifty-eight panellists completed both rounds (response rate 90%). Forty-five (70%) panellists thought that for LBP a case definition can be based on symptoms only. Consensus was only reached for work-related medial elbow tendinopathy, while the lowest agreement was found for knee osteoarthritis. Where consensus was not reached, this was - except for LBP - related to physical examination and imaging rather than disagreement on key symptoms. CONCLUSION: Consensus on case definitions was reached only for work-related medial elbow tendinopathy. Epidemiological research would benefit from harmonized case definitions for all MSDs including imaging and physical examination for LRS, SAPS, CTS, lateral elbow tendinopathy and hip and knee osteoarthritis.
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Dolor de la Región Lumbar , Enfermedades Musculoesqueléticas , Osteoartritis de la Cadera , Osteoartritis de la Rodilla , Técnica Delphi , Humanos , Dolor de la Región Lumbar/diagnóstico , Dolor de la Región Lumbar/epidemiología , Enfermedades Musculoesqueléticas/diagnóstico , Enfermedades Musculoesqueléticas/epidemiologíaRESUMEN
National standards for surgical respirators and masks are written and enforced to protect healthcare workers from particles and microorganisms such as Severe Acute Respriatory Syndrome Coronavirus 2 (SARS-CoV-2). In addition to the ability to filter particles (e.g. filtration efficiency, FE), the standards address breathability (e.g. differential pressure), how well the mask seals to a worker's face (e.g. fit test), the level of protection from a fluid splash, and other factors. Standards used in the USA, European Union (EU), and China were compared with respect to testing methods and certification criteria. Although there are substantial similarities in standards for respirators, such as surgical N95, FFP2, and KN95 filtering facepiece respirators (FFRs), there are differences with respect to who performs that testing and fit-testing requirements that influence certification. There is greater variation in test methods between countries for surgical (USA) or medical (EU and China) masks than for FFRs. Surgical/medical masks can be certified to different levels of protection. The impact of the similarities and differences in testing methods and certification criteria on FFR and mask performance for protecting healthcare workers from SARS-CoV-2 are discussed, as well as the value of a new standard in the EU for testing fabrics for masks used by the public. Health and safety personnel in healthcare settings must understand the differences between standards so that they can select respirators and masks that provide appropriate protection for healthcare workers.
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COVID-19 , Exposición Profesional , China , Personal de Salud , Humanos , Máscaras , Exposición Profesional/prevención & control , Pandemias , SARS-CoV-2 , Ventiladores MecánicosRESUMEN
The World Health Organization and the United States Centers for Disease Control have recommended universal face masking by the general public to slow the spread of COVID-19. A number of recent studies have evaluated the filtration efficiency and pressure differential (an indicator of breathability) of various, widely available materials that the general public can use to make face masks at home. In this review, we summarize those studies to provide guidance for both the public to select the best materials for face masks and for future researchers to rigorously evaluate and report on mask material testing. Of the tested fabric materials and material combinations with adequate breathability, most single and multilayer combinations had a filtration efficiency of <30%. Most studies evaluating commonly available mask materials did not follow standard methods that would facilitate comparison across studies, and materials were often described with too few details to allow consumers to purchase equivalent materials to make their own masks. To improve the usability of future study results, researchers should use standard methods and report material characteristics in detail.
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COVID-19 , Máscaras , Filtración , Humanos , SARS-CoV-2 , TextilesRESUMEN
BACKGROUND: The aim of this study was to identify case definitions of diagnostic criteria for specific musculoskeletal disorders (MSDs) for use in occupational healthcare, surveillance or research. METHODS: A scoping review was performed in Medline and Web of Science from 2000 to 2020 by an international team of researchers and clinicians, using the Arksey and O'Malley framework to identify case definitions based on expert consensus or a synthesis of the literature. Seven MSDs were considered: non-specific low back pain (LBP), lumbosacral radicular syndrome (LRS), subacromial pain syndrome (SAPS), carpal tunnel syndrome (CTS), lateral or medial elbow tendinopathy, and knee and hip osteoarthritis (OA). Case definitions for occupational healthcare or research were charted according to symptoms, signs and instrumental assessment of signs, and if reported, on work-related exposure criteria. RESULTS: In total, 2404 studies were identified of which 39 were included. Fifteen studies (38%) reported on non-specific LBP, followed by knee OA (n = 8;21%) and CTS (n = 8;21%). For non-specific LBP, studies agreed in general on which symptoms (i.e., pain in lower back) and signs (i.e., absence of red flags) constituted a case definition while for the other MSDs considerable heterogeneity was found. Only two studies (5%), describing case definitions for LBP, CTS, and SAPS and lateral and medial elbow tendinopathy respectively, included work-related exposure criteria in their clinical assessment. CONCLUSION: We found that studies on non-specific LBP agreed in general on which symptoms and signs constitute a case definition, while considerable heterogeneity was found for the other MSDs. For prevention of work-related MSDs, these MSD case definitions should preferably include work-related exposure criteria.
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Síndrome del Túnel Carpiano , Enfermedades Musculoesqueléticas , Enfermedades Profesionales , Consenso , Atención a la Salud , Humanos , Enfermedades Musculoesqueléticas/diagnóstico , Enfermedades Musculoesqueléticas/epidemiología , Enfermedades Profesionales/diagnóstico , Enfermedades Profesionales/epidemiologíaRESUMEN
Introduction: During a pandemic, when the supply of N95 filtering facepiece respirators (FFRs) is limited, FFRs may be decontaminated by methods that inactivate pathogens as long as they do not damage FFR function. Hydrogen peroxide (H2O2) is widely used for decontamination in medical settings. Objective: To review the literature on the use of H2O2 to decontaminate N95 FFRs and identify methods that inactivate virus and preserve FFR filtration efficiency and fit. Methods: The literature was searched for studies evaluating H2O2 decontamination methods on inactivating SARS-CoV-2 and other viruses and microorganisms inoculated on N95 FFRs and the effects on respirator filtration efficiency and fit. Current U.S. Federal guidelines are also presented. Results: Findings from relevant laboratory studies (N = 24) are summarized in tables. Commercially available H2O2 decontamination systems differ on how H2O2 is delivered, the temperature, the duration of treatment, and other factors that can impact N95 FFR filtration efficiency and fit. Some methods inactivate SARS-CoV-2 virus-contaminated N95 FFRs with >3 log attenuation, whereas other methods are yet to be evaluated. Discussion and Conclusion: Most of the H2O2 methods reviewed effectively decontaminate N95 FFRs without damaging FFR function. However, some methods adversely impact N95 fit or filtration efficiency, which could go undetected by the end user and compromise their protection from pathogen inhalation. When making decisions about H2O2 decontamination of respirators, it is important to understand differences in methods, effects on different FFR models, and potential hazards to workers who manage the decontamination process.
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BACKGROUND AND AIMS: Endoscopists experience upper extremity musculoskeletal injuries. The primary aim of this study was to compare distal upper extremity biomechanical risk factors during colonoscopy with established risk thresholds. Secondary aims were to determine which subtasks during colonoscopy are associated with the greatest risk and to evaluate an intervention to reduce risks. METHODS: Twelve endoscopists performed 2 to 4 colonoscopies while thumb pinch force and forearm muscle loads of extensor carpi radialis (ECR) and flexor digitorum superficialis (FDS) muscles were collected. Peak exertion values were analyzed using amplitude probability distribution functions. An endoscope support device was evaluated during simulated colonoscopy (n = 8). RESULTS: Mean endoscopist age was 42.3 years; 67% were men. Peak thumb pinch force exceeded risk thresholds for pinch force (10 N) and percent of time spent in forceful pinch for all colonoscopy subtasks. Peak ECR and FDS muscle activity exceeded the action limit (10% maximum voluntary contraction [MVC]) in both forearms. Peak left FDS, left ECR, and right ECR activity exceeded the threshold limit value (>30% MVC). Peak left FDS and ECR activity were significantly greater during insertion than during withdrawal (P < .05). Peak right FDS and ECR activity were significantly greater during right colon insertion compared with withdrawal (P < .05). The endoscope support device reduced left ECR muscle activity (P = .02). CONCLUSIONS: Thumb pinch forces and time spent in forceful pinch indicate high-risk exposures during colonoscopy. Left wrist extensor muscle activity exceeded established thresholds with the greatest risk occurring during insertion. An endoscope support device reduced loads to the left wrist extensors.
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Antebrazo , Enfermedades Musculoesqueléticas , Adulto , Colonoscopía , Electromiografía , Femenino , Humanos , Masculino , Enfermedades Musculoesqueléticas/etiología , Factores de RiesgoRESUMEN
Many academics and researchers have responded to the COVID-19 pandemic by forming on-line national and international collaborative groups to rapidly investigate issues of prevention and treatment. This commentary describes the spontaneous formation of an international team of 115 researchers who summarized the literature on safe methods for decontaminating N95 filtering facepiece respirators in response to the supply crisis. The summary reports and fact sheets on the (www.n95decon.org) website have had more than 200 000 unique visits and the organization's webinars have reached health care professionals from more than 50 countries. The team is extending its mission to cover other personal protective equipment. The success of these collaborations may alter how scientific questions are tackled in the future.
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Infecciones por Coronavirus/prevención & control , Descontaminación/métodos , Cooperación Internacional , Pandemias/prevención & control , Neumonía Viral/prevención & control , Dispositivos de Protección Respiratoria , Betacoronavirus , COVID-19 , Contaminación de Equipos , Equipo Reutilizado , Humanos , Exposición Profesional/prevención & control , Dispositivos de Protección Respiratoria/provisión & distribución , Dispositivos de Protección Respiratoria/virología , SARS-CoV-2RESUMEN
Lifting equipment can reduce the risk of injury from patient handling, but limited availability and adoption have been a persistent problem. Data from statewide surveys of California nurses (Nâ¯=â¯389) in 2013 and 2016 were analyzed to evaluate lift use, perceptions about lifts and injury risk, and musculoskeletal symptoms by type of available lifts. Nurses with ceiling lifts (23%) were significantly more likely to use lifts and had more positive perceptions about lifts, regarding worker safety, patient safety and comfort, ease of use, access, and storing, than nurses with only floor lifts (77%). Nurses with ceiling lifts reported less low back pain and shoulder pain. Our study findings suggest that providing ceiling lifts can result in superior outcomes to floor-based lifts in multiple aspects, including better acceptance and use by nurses for patient handling, as well as being associated with reduced work-related musculoskeletal symptoms in the low back and shoulders.
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Actitud del Personal de Salud , Movimiento y Levantamiento de Pacientes/instrumentación , Personal de Enfermería en Hospital , Enfermedades Profesionales/prevención & control , California , Estudios Transversales , Ergonomía , Humanos , Dolor de la Región Lumbar/prevención & control , Persona de Mediana Edad , Dimensión del Dolor , Dolor de Hombro/prevención & control , Encuestas y CuestionariosRESUMEN
Recent studies have shown the 2001 American Conference of Governmental Industrial Hygienists (ACGIH®) Threshold Limit Value (TLV®) for Hand Activity was not sufficiently protective for workers at risk of carpal tunnel syndrome (CTS). These studies led to a revision of the TLV and Action Limit. This study compares the effect of applying the 2018 TLV vs. the 2001 TLV to predict incident CTS within a large occupational pooled cohort study (n = 4,321 workers). Time from study enrollment to first occurrence of CTS was modeled using Cox proportional hazard regression. Adjusted and unadjusted hazard ratios for incident CTS were calculated using three exposure categories: below the Action Limit, between the Action Limit and TLV, and above the TLV. Workers exposed above the 2001 Action Limit demonstrated significant excess risk of carpal tunnel syndrome, while the 2018 TLV demonstrated significant excess risk only above the TLV. Of 186 total cases of CTS, 52 cases occurred among workers exposed above the 2001 TLV vs. 100 among those exposed above the 2018 value. Eliminating exposures above the 2001 TLV might have prevented 11.2% of all cases of CTS seen in our pooled cohort, vs. 25.1% of cases potentially prevented by keeping exposures below the 2018 value. The 2018 revision of the TLV better protects workers from CTS, a recognized occupational health indicator important to public health. A significant number of workers are currently exposed to forceful repetitive hand activity above these guidelines. Public health professionals should promulgate these new guidelines and encourage employers to reduce hand intensive exposures to prevent CTS and other musculoskeletal disorders.
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Síndrome del Túnel Carpiano/etiología , Enfermedades Profesionales/etiología , Salud Laboral/normas , Medición de Riesgo/normas , Valores Limites del Umbral , Adolescente , Adulto , Anciano , Síndrome del Túnel Carpiano/epidemiología , Estudios de Cohortes , Femenino , Humanos , Masculino , Persona de Mediana Edad , Enfermedades Profesionales/epidemiología , Factores de Riesgo , Adulto JovenRESUMEN
Drilling large holes (e.g., 10-20 mm diameter) into concrete for structural upgrades to buildings, highways, bridges, and airport runways can produce concentrations of respirable silica dust well above the ACGIH® Threshold Limit Value (TLV® = 0.025 mg/m3). The aim of this study was to evaluate a new method of local exhaust ventilation, hollow bit dust extraction, and compare it to a standard shroud local exhaust ventilation and to no local exhaust ventilation. A test bench system was used to drill 19 mm diameter x 100 mm depth holes every minute for one hour under three test conditions: no local exhaust ventilation, shroud local exhaust ventilation, and hollow bit local exhaust ventilation. There were two trials for each condition. Respirable dust sampling equipment was placed on a "sampling" mannequin fixed behind the drill and analysis followed ISO and NIOSH methods. Without local exhaust ventilation, mean respirable dust concentration was 3.32 (± 0.65) mg/m3 with a quartz concentration of 16.8% by weight and respirable quartz dust concentration was 0.55 (± 0.05) mg/m3; 22 times the ACGIH TLV. For both LEV conditions, respirable dust concentrations were below the limits of detection. Applying the 16.8% quartz value, respirable quartz concentrations for both local exhaust ventilation conditions were below 0.007 mg/m3. There was no difference in respirable quartz dust concentrations between the hollow bit and the shroud local exhaust ventilation systems; both were below the limits of detection and well below the ACGIH TLV. Contractors should consider using either local exhaust ventilation method for controlling respirable silica dust while drilling into concrete.
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Contaminantes Ocupacionales del Aire/análisis , Cuarzo/análisis , Ventilación/métodos , Industria de la Construcción/instrumentación , Polvo/análisis , Exposición por Inhalación/análisis , Exposición Profesional/prevención & controlRESUMEN
OBJECTIVES: Both pneumatic rock drills and electric rotary hammer drills are used for drilling large holes (e.g., 10-20â¯mm diameter) into concrete for structural upgrades to buildings, highways, bridges, and airport tarmacs. However, little is known about the differences in productivity, and exposures to noise, handle vibration, and dust between the two types of drills. The aim of this study was to compare these outcomes with similar mass electric rotary and pneumatic rock drills drilling into concrete block on a test bench system. METHOD: Three experiments were conducted on a test bench system to compare an electric (8.3â¯kg) and pneumatic drill (8.6â¯kg) on (1) noise and handle vibration, (2) respirable silica dust, and (3) drilling productivity. The test bench system repeatedly drilled 19â¯mm diameter x 100â¯mm depth holes into cured concrete block while the respective exposure levels were measured following ISO standards. RESULTS: Productivity levels were similar between the electric and the pneumatic drill (9.09â¯mm/s vs. 8.69â¯mm/s ROP; pâ¯=â¯0.15). However, peak noise (LPeak: 117.7 vs. 139.4 dBC; pâ¯=â¯0.001), weighted total handle vibration (ahw: 7.15 vs. 39.14â¯m/s2; pâ¯=â¯0.002), and respirable silica dust levels (0.55 vs. 22.23â¯mg/m3; pâ¯=â¯0.003) were significantly lower for the electric than the pneumatic drill. DISCUSSION: While there were no differences in drilling productivity between an electric and pneumatic drill of similar mass, there were substantial differences in exposure levels of noise, handle vibration, and respirable silica dust. Structural contractors should switch from pneumatic rock drills to electric rotary hammer drills for structural drilling into concrete in order to reduce worker exposures to the hazards of noise, hand vibration, and silica dust.