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Evaluation of work station design factors in VDT operations
Controls 13.4.24 (82513)
Banks, W.W., and Boone, M.P. A method for quantifying control accessibility. Human Factors, Jun 1981, 23.3, 2 9 9 - 3 0 3 . A method of statistically quantifying the accessibility of controls was proposed and validated. The results index of accessibility (Ia) takes into account three sources of variability: operator's reach envelope, frequency of use, and relative physical position of controls with respect to the operator. Operator ratings and measurement (percent of controls reached) were significantly correlated with I a values, lending support to the notion that I a is a valid and sensitive measure of control placement.
Workplace layout and equipment design 13.4.25 (82321) Stammerjohn, L.W., Smith, M.J., and Cohen, B.G.F. Evaluation of work station design factors in VDT operations. Human Factors, Aug 1981, 23.4, 4 0 1 - 4 1 2 . An on-site evaluation was conducted at five establishments using VDTs to examine VDT workstation designs and to compare these designs with recommendations obtained from the literature. Measurements were made of such critical design factors as keyboard height, screen height, workstation illumination, and glare. Illumination levels were generally in the 500 to 700 lx range, and questionnaire data confirmed that these levels were acceptable to most employees. A number of design problems were found in the VDT workstations, including excessive keyboard heights and screen positioning which would require excessive inclination of the head and neck for screen viewing. A majority of the operators surveyed found a number of factors to be bothersome, including screen readability, reflected glare, screen brightness, and flicker. A number of the dissatisfaction parameters were found to be related te levels of somatic (health) complaints.
Dubrovnik, Yugoslavia, 25-30 Sep 1978, Edited by R. Plestina. Institute for Medical Research and Occupational Health, Zagreb, Yugoslavia, 1980, 4, 1 7 2 5 - 1 7 3 4 . The purpose of this paper is to review the results of a preliminary survey conducted by the occupational health team regarding the main occupational health problems affiliated with the National Iranian Oil Company and other off-shore oil companies in the Persian Gulf, which began operating in 1958. The report is based upon the results obtained from questionnaires, direct communication with the authorities concerned, site visits and evaluation of some environmental factors. Environmental heat forms one of the major occupational health problems in this area. The average temperature in the shade in summer is about 40°C, with humidity spells as high as 100%. Despite such adverse climatic conditions no instances of clinical heat exhaustion are recorded, due to optimal air-conditioning of the living and recreational quarters, where the employees spend most of their time in hot seasons. The use of light clothing, protection from sunlight exposure (helmets, working in shade), consumption of adequate amount of salt and fluid are additional protective factors. Operational heat loss is increased by the outdoor nature of the operations. Occupational noise is another major problem. Diving operations take place in depths of 30 to 80 m. A mixture o f oxygen and helium is used instead of compressed air in depths greater than 50 m. Diving accidents have occurred less often than during similar operations in rough seas with cold waters. Other occupational health problems are reviewed and the difficulties of tackling them are discussed. Suggestions are made for a better control of occupational health problems of those companies. 13.4.27 (82378)
Suma'mur, P.K. Development of health and safety standards of work microclimate in Indonesia. In: Proceedings of the XIX
International Congress on Occupational Health, Dubrovnik, Yugoslavia, 25-30 Sep 1978, Edited by R. Plestina. Institute for Medical Research and Occupational Health, Zagreb, Yugoslavia, 1980, 4, 1 7 1 3 - 1 7 1 7 .
Thermal conditions 13.4.26 (82374) Aryanpur, J. Occupational health problems in offshore oil operations in Iran. In:
Proceedings of the XIX International Congress on Occupational Health,
As a tropical country, Indonesia should determine work microclimate standards to safeguard the human factor in the working environment. Average air temperature in this country ranges from 24"0 to 27" I°C, with relative humidity never less than 65%. Radiation heat is usually 2 8 - 2 9 ° C indoors and 30°C outdoors. Evaporation is an
important mechanism ensuring a balanced body temperature. Unless the fluid balance is maintained, body weight will be reduced. A wet bulb temperature of 30°C is generally considered as the point at which some untoward effects become observable. The Belding Hatch Index indicated very high percentages, although no complaints on the part of the workers were recorded. Further study showed that a wet bulb globe thermometer (WBGT) assessment might have been more suitable. For WBGT less than 27"7°C there were no complaints or sensation of heat stress, the latter becoming noticeable at 28-9-29.6°C. When the WBGT exceeds 30-2°C, the heat stress becomes unbearable. For cold workplaces, the threshold is 21°C wet bulb. The comfort zone is about 2 4 - 2 6 ° C dry bulb. 13.4.28 (82381)
Henane, R., et al Thermal strain resulting from protective clothing of an armoured vehicle crew in warm conditions. Aviation, Space and Environmental Medicine, Jun 1979, 50.6, 5 9 9 - 6 0 3 . The purpose of the study is to define a method of evaluation of physiological strain resulting from protective garments worn in warm conditions by the armoured vehicle crew. A technique is developed evaluating evaporative transfer through clothing by continuous weighing of the active man (accuracy +3/g). An index is defined (Iw) as the ratio of steadystate evaporative rate in clothed conditions to steady-state evaporation of nude subject in the same conditions of work and heat stress. The I w index is significantly related to physiological strain determined by increased body heat content and reduced tolerance time. The results are compared to other previous findings concerning evaporative transfer through clothing and physiological strain indexes. The technique shows that evaporation through heavy clothing is not negligible. It is suggested that usual static measurements using physical models underestimate the evaporative heat transfer through clothing layers.
Altitude and depth 13.4.29 (82391) Weybrew, B.B., and Noddin, E.M. Psychiatric aspects of adaptation to long submarine missions. Aviation,
Space and Environmental Medicine, Jun 1979, 50.6, 5 7 5 - 5 8 0 . The case histories of 261 submariners disqualified psychiatrically for further submarine duty revealed that the
Applied Ergonomics December 1982
309
Banks, W.W., and Boone, M.P. A method for quantifying control accessibility. Human Factors, Jun 1981, 23.3, 2 9 9 - 3 0 3 . A method of statistically quantifying the accessibility of controls was proposed and validated. The results index of accessibility (Ia) takes into account three sources of variability: operator's reach envelope, frequency of use, and relative physical position of controls with respect to the operator. Operator ratings and measurement (percent of controls reached) were significantly correlated with I a values, lending support to the notion that I a is a valid and sensitive measure of control placement.
Workplace layout and equipment design 13.4.25 (82321) Stammerjohn, L.W., Smith, M.J., and Cohen, B.G.F. Evaluation of work station design factors in VDT operations. Human Factors, Aug 1981, 23.4, 4 0 1 - 4 1 2 . An on-site evaluation was conducted at five establishments using VDTs to examine VDT workstation designs and to compare these designs with recommendations obtained from the literature. Measurements were made of such critical design factors as keyboard height, screen height, workstation illumination, and glare. Illumination levels were generally in the 500 to 700 lx range, and questionnaire data confirmed that these levels were acceptable to most employees. A number of design problems were found in the VDT workstations, including excessive keyboard heights and screen positioning which would require excessive inclination of the head and neck for screen viewing. A majority of the operators surveyed found a number of factors to be bothersome, including screen readability, reflected glare, screen brightness, and flicker. A number of the dissatisfaction parameters were found to be related te levels of somatic (health) complaints.
Dubrovnik, Yugoslavia, 25-30 Sep 1978, Edited by R. Plestina. Institute for Medical Research and Occupational Health, Zagreb, Yugoslavia, 1980, 4, 1 7 2 5 - 1 7 3 4 . The purpose of this paper is to review the results of a preliminary survey conducted by the occupational health team regarding the main occupational health problems affiliated with the National Iranian Oil Company and other off-shore oil companies in the Persian Gulf, which began operating in 1958. The report is based upon the results obtained from questionnaires, direct communication with the authorities concerned, site visits and evaluation of some environmental factors. Environmental heat forms one of the major occupational health problems in this area. The average temperature in the shade in summer is about 40°C, with humidity spells as high as 100%. Despite such adverse climatic conditions no instances of clinical heat exhaustion are recorded, due to optimal air-conditioning of the living and recreational quarters, where the employees spend most of their time in hot seasons. The use of light clothing, protection from sunlight exposure (helmets, working in shade), consumption of adequate amount of salt and fluid are additional protective factors. Operational heat loss is increased by the outdoor nature of the operations. Occupational noise is another major problem. Diving operations take place in depths of 30 to 80 m. A mixture o f oxygen and helium is used instead of compressed air in depths greater than 50 m. Diving accidents have occurred less often than during similar operations in rough seas with cold waters. Other occupational health problems are reviewed and the difficulties of tackling them are discussed. Suggestions are made for a better control of occupational health problems of those companies. 13.4.27 (82378)
Suma'mur, P.K. Development of health and safety standards of work microclimate in Indonesia. In: Proceedings of the XIX
International Congress on Occupational Health, Dubrovnik, Yugoslavia, 25-30 Sep 1978, Edited by R. Plestina. Institute for Medical Research and Occupational Health, Zagreb, Yugoslavia, 1980, 4, 1 7 1 3 - 1 7 1 7 .
Thermal conditions 13.4.26 (82374) Aryanpur, J. Occupational health problems in offshore oil operations in Iran. In:
Proceedings of the XIX International Congress on Occupational Health,
As a tropical country, Indonesia should determine work microclimate standards to safeguard the human factor in the working environment. Average air temperature in this country ranges from 24"0 to 27" I°C, with relative humidity never less than 65%. Radiation heat is usually 2 8 - 2 9 ° C indoors and 30°C outdoors. Evaporation is an
important mechanism ensuring a balanced body temperature. Unless the fluid balance is maintained, body weight will be reduced. A wet bulb temperature of 30°C is generally considered as the point at which some untoward effects become observable. The Belding Hatch Index indicated very high percentages, although no complaints on the part of the workers were recorded. Further study showed that a wet bulb globe thermometer (WBGT) assessment might have been more suitable. For WBGT less than 27"7°C there were no complaints or sensation of heat stress, the latter becoming noticeable at 28-9-29.6°C. When the WBGT exceeds 30-2°C, the heat stress becomes unbearable. For cold workplaces, the threshold is 21°C wet bulb. The comfort zone is about 2 4 - 2 6 ° C dry bulb. 13.4.28 (82381)
Henane, R., et al Thermal strain resulting from protective clothing of an armoured vehicle crew in warm conditions. Aviation, Space and Environmental Medicine, Jun 1979, 50.6, 5 9 9 - 6 0 3 . The purpose of the study is to define a method of evaluation of physiological strain resulting from protective garments worn in warm conditions by the armoured vehicle crew. A technique is developed evaluating evaporative transfer through clothing by continuous weighing of the active man (accuracy +3/g). An index is defined (Iw) as the ratio of steadystate evaporative rate in clothed conditions to steady-state evaporation of nude subject in the same conditions of work and heat stress. The I w index is significantly related to physiological strain determined by increased body heat content and reduced tolerance time. The results are compared to other previous findings concerning evaporative transfer through clothing and physiological strain indexes. The technique shows that evaporation through heavy clothing is not negligible. It is suggested that usual static measurements using physical models underestimate the evaporative heat transfer through clothing layers.
Altitude and depth 13.4.29 (82391) Weybrew, B.B., and Noddin, E.M. Psychiatric aspects of adaptation to long submarine missions. Aviation,
Space and Environmental Medicine, Jun 1979, 50.6, 5 7 5 - 5 8 0 . The case histories of 261 submariners disqualified psychiatrically for further submarine duty revealed that the
Applied Ergonomics December 1982
309