Work - Volume 47, issue 1

Authors: Eger, Tammy | Thompson, Aaron | Leduc, Mallorie | Krajnak, Kristine | Goggins, Katie | Godwin, Alison | House, Ron

Article Type: Research Article

Abstract: BACKGROUND: Workers who stand on platforms or equipment that vibrate are exposed to foot-transmitted vibration (FTV). Exposure to FTV can lead to vibration white feet/toes resulting in blanching of the toes, and tingling and numbness in the feet and toes. OBJECTIVES: The objectives are 1) to review the current state of knowledge of the health risks associated with foot-transmitted vibration (FTV), and 2) to identify the characteristics of FTV and discuss the associated risk …of vibration-induced injury. PARTICIPANTS: Workers who operated locomotives (n=3), bolting platforms (n=10), jumbo drills (n=7), raise drilling platforms (n=4), and crushers (n=3), participated. METHODS: A tri-axial accelerometer was used to measure FTV in accordance with ISO 2631-1 guidelines. Frequency-weighted root-mean-square acceleration and the dominant frequency are reported. Participants were also asked to report pain/ache/discomfort in the hands and/or feet. RESULTS: Reports of pain/discomfort/ache were highest in raise platform workers and jumbo drill operators who were exposed to FTV in the 40 Hz and 28 Hz range respectively. Reports of discomfort/ache/pain were lowest in the locomotive and crusher operators who were exposed to FTV below 10 Hz. These findings are consistent with animal studies that have shown vascular and neural damage in exposed appendages occurs at frequencies above 40 Hz. CONCLUSIONS: Operators exposed to FTV at 40 Hz appear to be at greater risk of experiencing vibration induced injury. Future research is required to document the characteristics of FTV and epidemiological evidence is required to link exposure with injury. Show more

Keywords: Occupational vibration, Raynaud's, white-foot, standing, vibration white-toes

DOI: 10.3233/WOR-131692

Citation: Work, vol. 47, no. 1, pp. 101-110, 2014

Authors: Hunt, S. | Boyle, C. | Wells, R.

Article Type: Research Article

Abstract: BACKGROUND: Electrical utility workers wear thick rubber gloves and often work in the cold. OBJECTIVE: To document the challenge of working in the cold and the effectiveness of different glove/liner combinations in keeping workers' hands warm. METHODS: Ten experienced male electrical utility employees worked in a controlled temperature walk-in chamber at −20°C for 45 minutes for each of five glove conditions: standard five-finger rubber gloves with cotton liners and gauntlets, mitten style …gloves, a prototype wool liner, and two heating options; glove or torso. Dependent measures were maximum grip force, skin temperatures, finger dexterity and sensitivity to touch, ratings of perceived effort and a rating of thermal sensation. RESULTS: Participants' hand skin temperatures decreased, they perceived their hands to be much colder, their finger sensitivity decreased and their ratings of perceived exertion increased, however their performance did not degrade over the 45 minute trials. The mitten-style gloves showed a smaller drop in skin temperature for the 3rd and 5th digits (p< 0.05) than the other glove conditions. CONCLUSIONS: Mitten style gloves kept workers' hands warmer than the standard five finger glove. Show more

Keywords: Grip, strength, temperature, dexterity, heating

DOI: 10.3233/WOR-131754

Citation: Work, vol. 47, no. 1, pp. 111-121, 2014

Authors: Conrad, Leanne F. | Oliver, Michele L. | Jack, Robert J. | Dickey, James P. | Eger, Tammy R.

Article Type: Research Article

Abstract: OBJECTIVE: The purpose of this work was to help a steel industry partner select the most appropriate of three high end heavy equipment seats to retrofit a number of their heavy mobile machines used in the steel making process. PARTICIPANTS: The participants included 8 males (22.3 ± 2.0 yrs.) and 8 females (23.5 ± 1.8 yrs.) with no experience operating heavy mobile equipment. METHODS: Previously recorded 6-DOF chassis acceleration data from a …Pot Hauler (a machine which picks up and transports pots of slag) were used to extract six, 20 second representative profiles for implementation on a lab-based heavy machine simulator (6-DOF Parallel Robotics System Corporation robot). Subjects sat on three heavy equipment seats (BeGe7150, Grammar MSG 95G1721, and a 6801 Isringhausen with the seat pan cushion retrofitted with a Skydex™ cushion) mounted on the simulator. Each subject completed three trials for each combination of seat (n=3) and vibration profile (n=6). Chassis and operator/seat interface vibration were measured by 2, 6-DOF vibration transducers. Variables included Seat Effective Amplitude Transmissibility (SEAT) (X,Y,Z,Roll,Pitch,Yaw,6DOF Vector Sum) to determine if the seat was attenuating or amplifying the vibration, 6-degree of freedom (DOF) vibration total value weighted predicted comfort (A_{vc} ) (according to ISO 2631-1) and operator reported comfort (ORC). RESULTS: Factorial ANOVAs revealed significant differences (p⩽ 0.05) between seats for all SEAT variables but different seats performed better than others depending on the axis. Significant differences between males and females were observed for SEAT in X,Y, and Pitch as well as for A_{vc} . As expected there were significant differences between vibration profiles for all assessed variables. A number of interaction effects were observed, the most frequently occurring of which was between seat and vibration profile. CONCLUSIONS: Based upon the number of seat and vibration profile interactions, results suggest that a single seat is not suited for all tested conditions. However, SEAT values for all of the seats tested were extremely low (e.g., 6-DOF SEAT < 30%) indicating that all of the seats were capable of providing good vibration attenuation. Show more

Keywords: Whole-body vibration, operator reported comfort, seat selection, ISO 2631-1(1997)

DOI: 10.3233/WOR-131758

Citation: Work, vol. 47, no. 1, pp. 123-136, 2014

Authors: Stevenson, Joan M.

Article Type: Research Article

Abstract: Over my career I have been involved in research covering three different strategies to reduce workplace injuries, namely: (a) developing bona fide occupational requirements for physically demanding jobs, (b) conducting training programs and a case-control study of low back pain in industry, and (c) developing ergonomically-designed equipment and tools. The purpose of this paper is to identify some areas where I believe research is needed to reduce the risks of musculoskeletal disorders. Hopefully, new researchers will …pick up the torch on some of these topics and continue to enhance the impact of occupational biomechanics and ergonomics on improving jobs for workers. Show more

Keywords: Employee selection, biomechanical, ergonomics, manual materials handling, low back disability

DOI: 10.3233/WOR-131691

Citation: Work, vol. 47, no. 1, pp. 137-141, 2014