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Further development of a non-linear hearing defender
training and repeated wearing subjects could experience a significant adaptation to discomfort. Ten subjects t o o k part in the trial in a tropical environhaent by wearing helmets repeatedly (6 h per day) for one month. Subjective evaluations of discomfort were made at the end of the 1st, 3rd, 5th, 14th and 30th day. It was revealed that complaints of discomfort, viz, hotness, heaviness, bad fit, ere, decreased markedly throughout the 30-day period. Though positive responses of adaptation to discomfort seem to reach an optimum towards 30 days, it is difficult to draw any conclusions on the optimum period of adaptation for each discomfort factor• In relation to inherent discomforts that are extremely difficult to overcome without compromising the protection efficiency of a PPD, the principle of adaptation seems to be a very important facet which has to be developed for an effective PPD programme.
22.2.58 (119358)
Nielson, R., Gavhed, D.C.E., and Nilsson, H. Tlaermal function of-a clothing ensemble during work: dependency on inner clothing layer fit. Ergonomics, 1989, 32.12, 1 5 8 1 - 1 5 9 4 , 35 refs. A tight-fitting crewneck undergarment (U) and a loose-fitting shirt (S) were studied as part of a commonlyused clothing ensemble (lto t = 0-22 m K/W). Ten clothed male subjects performed standardised packing work (VO2 = 0.76 1/min) at three climatic conditions, 20°C and V a = 0.45 m/s ( 0 - 3 0 min), at 5°C and V a = 0"39 m/s ( 3 0 - 6 0 min) and at 5°C and V a = 1.23 m/s ( 7 6 - 9 0 rain). F r o m 6 0 - 7 5 min the subjects rested at 200C. The physiological and subjective responses varied with the environment from slightly warm to cool. U resulted in warmer responses than S: torso and upper arm skin temperatures were hzgher at both 5 C and 20 C, evaporatzon rate was h~gher at 20 C, mean skin temperature was higher during work at 20 C, sweating tended to begin earlier and skin wettedness to be higher with U than with S. No differences were observed in core temperature, heart rates and subjective thermal evaluations. It was concluded that a tight-fitting inner layer (U) compared with a loose-fitting one (S) allows for less cooling of the skin in both a cool and a slightly warm environment. .
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22.2.57 (119351)
Lees, A., and Thornley, N.J. The effect of a running shoe air circulation system on the temperature and sweat accumulation of the foot during running. In: E.J. Lovesey (Ed). Contemporary Ergonomics 1990, Taylor & Francis, London, 1990, pp 1 5 4 - 1 5 9 , 5 refs. A running shoe air circulation system, known as the 'whirlwind' system, was tested for its effectiveness in reducing in-shoe temperature and sweat accumulation during running. Eight healthy male subjects each performed six trials of 40-rain duration on a treadmill. Four of the subjects ran at 3.5 m/s whilst the other four ran at 3.0 m/s. Each subject performed three trials using the 'whirlwind' system running shoe and three in an identical shoe without the system. Results showed that the foot temperature reached an asymptote after 20 rain of running. The mean increase in foot temperature was 7-4°C and the mean sweat accumulation was 5.57 g. There were no significant differences between the 'whirlwind' system and the identical shoe without the system. There was a significant difference (p < 0.05) for both variables between the two running speeds. It was concluded that the shoe promoted the build-up of heat in the foot, and this was n o t ameliorated by the air circulation system under investigation.
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22.2.59 (119365)
Watson, P.R. Further development of a non-linear hearing defender. Report on Project No 7249-13-019 for Community Ergonomics Action, European Coal and Steel Community, Luxembourg, 1988, 53 pp, 0 refs. A study by the Institute of Occupational Medicine identifies a particular requirement for a form of non-linear hearing protector device to be used in intermittent loud noise. The repeated donning of earmuffs is inconvenient, but when worn, the middle and highfrequency attenuation of the muffs prevents normal conversation. Also lost is much of the audible information from the working environment. The use of a hearing p r o t e c t o r which has an attenuation characteristic dependent on noise level is therefore potentially attractive. The Institute of Sound and Vibration Research had separately developed a device of this type which was submitted for e~,aluation. The out-
come was that ISVR was awarded a contract to modify the design in a number of respects, to produce a number for evaluation, and to examine a n u m b e r of associated matters relating to the production and use of the device underground. The requirement was for a hearing protector exhibiting a flat attenuation characteristic providing 1 0 - 1 5 dB(A) of assumed protection.
22.2.60 (119367)
Jette, M., Thoden, J., and Livingstone, S. Physiological effects of inspiratory resistance on progressive aerobic work.
Europ Y Applied Physiol and Occupat Physiol, 1990, 60.1, 6 5 - 7 0 , 18 refs. The purpose of this study was to determine the potential effects on progressive aerobic work while breathing through a new military t y p e chemical and biological (CB) respirator loaded with three different types of purifying canisters. Twelve healthy well-motivated male subjects (mean age 23 + 3 years) participated in the study. Results indicated that mean maximal oxygen uptake (VO 2 max), time to exhaustion, respiratory exchange ratio, rate of perceived exertion, respiratory rate and tidal volume at exhaustion, maximal lactate and the 2-rain post-exercise lactate were not significantly influenced; when breathing with the respirator and the canisters in comparison with a laboratory valve. Mean pulmonary ventilation, however, was reduced by 21% while oxygen and carbon dioxide ventilatory equivalents were significantly lower by 9% and 8% respectively. Review of the stage-by-stage responses" to the treadmill test between the laboratory valve and respirator/canister conditions indicated no significant differences (NS) in oxygen uptake but slightly lower heart rates (NS). Ventilation was not influenced by the canisters until 80% of VO2 m a x , at which time the mean oxygen ventilatory equivalent became significantly lower. Blood lactate was significantly depressed between 60% and 90% VO2 max under the respiratory/canister conditions. It was concluded that, although physiological adaptation occurred, breathing with the new CB respirator and each of the three purifying canisters had no detrimental effect on progressive aerobic work to exhaustion. However, prolonged work at intensities greater than 8 0 - 8 5 % of VO 2 max would in all probability be impaired when breathing with the CB mask and the canisters.
Applied Ergonomics April 1991
137
22.2.58 (119358)
Nielson, R., Gavhed, D.C.E., and Nilsson, H. Tlaermal function of-a clothing ensemble during work: dependency on inner clothing layer fit. Ergonomics, 1989, 32.12, 1 5 8 1 - 1 5 9 4 , 35 refs. A tight-fitting crewneck undergarment (U) and a loose-fitting shirt (S) were studied as part of a commonlyused clothing ensemble (lto t = 0-22 m K/W). Ten clothed male subjects performed standardised packing work (VO2 = 0.76 1/min) at three climatic conditions, 20°C and V a = 0.45 m/s ( 0 - 3 0 min), at 5°C and V a = 0"39 m/s ( 3 0 - 6 0 min) and at 5°C and V a = 1.23 m/s ( 7 6 - 9 0 rain). F r o m 6 0 - 7 5 min the subjects rested at 200C. The physiological and subjective responses varied with the environment from slightly warm to cool. U resulted in warmer responses than S: torso and upper arm skin temperatures were hzgher at both 5 C and 20 C, evaporatzon rate was h~gher at 20 C, mean skin temperature was higher during work at 20 C, sweating tended to begin earlier and skin wettedness to be higher with U than with S. No differences were observed in core temperature, heart rates and subjective thermal evaluations. It was concluded that a tight-fitting inner layer (U) compared with a loose-fitting one (S) allows for less cooling of the skin in both a cool and a slightly warm environment. .
O
•
O
22.2.57 (119351)
Lees, A., and Thornley, N.J. The effect of a running shoe air circulation system on the temperature and sweat accumulation of the foot during running. In: E.J. Lovesey (Ed). Contemporary Ergonomics 1990, Taylor & Francis, London, 1990, pp 1 5 4 - 1 5 9 , 5 refs. A running shoe air circulation system, known as the 'whirlwind' system, was tested for its effectiveness in reducing in-shoe temperature and sweat accumulation during running. Eight healthy male subjects each performed six trials of 40-rain duration on a treadmill. Four of the subjects ran at 3.5 m/s whilst the other four ran at 3.0 m/s. Each subject performed three trials using the 'whirlwind' system running shoe and three in an identical shoe without the system. Results showed that the foot temperature reached an asymptote after 20 rain of running. The mean increase in foot temperature was 7-4°C and the mean sweat accumulation was 5.57 g. There were no significant differences between the 'whirlwind' system and the identical shoe without the system. There was a significant difference (p < 0.05) for both variables between the two running speeds. It was concluded that the shoe promoted the build-up of heat in the foot, and this was n o t ameliorated by the air circulation system under investigation.
O
.
O
.
22.2.59 (119365)
Watson, P.R. Further development of a non-linear hearing defender. Report on Project No 7249-13-019 for Community Ergonomics Action, European Coal and Steel Community, Luxembourg, 1988, 53 pp, 0 refs. A study by the Institute of Occupational Medicine identifies a particular requirement for a form of non-linear hearing protector device to be used in intermittent loud noise. The repeated donning of earmuffs is inconvenient, but when worn, the middle and highfrequency attenuation of the muffs prevents normal conversation. Also lost is much of the audible information from the working environment. The use of a hearing p r o t e c t o r which has an attenuation characteristic dependent on noise level is therefore potentially attractive. The Institute of Sound and Vibration Research had separately developed a device of this type which was submitted for e~,aluation. The out-
come was that ISVR was awarded a contract to modify the design in a number of respects, to produce a number for evaluation, and to examine a n u m b e r of associated matters relating to the production and use of the device underground. The requirement was for a hearing protector exhibiting a flat attenuation characteristic providing 1 0 - 1 5 dB(A) of assumed protection.
22.2.60 (119367)
Jette, M., Thoden, J., and Livingstone, S. Physiological effects of inspiratory resistance on progressive aerobic work.
Europ Y Applied Physiol and Occupat Physiol, 1990, 60.1, 6 5 - 7 0 , 18 refs. The purpose of this study was to determine the potential effects on progressive aerobic work while breathing through a new military t y p e chemical and biological (CB) respirator loaded with three different types of purifying canisters. Twelve healthy well-motivated male subjects (mean age 23 + 3 years) participated in the study. Results indicated that mean maximal oxygen uptake (VO 2 max), time to exhaustion, respiratory exchange ratio, rate of perceived exertion, respiratory rate and tidal volume at exhaustion, maximal lactate and the 2-rain post-exercise lactate were not significantly influenced; when breathing with the respirator and the canisters in comparison with a laboratory valve. Mean pulmonary ventilation, however, was reduced by 21% while oxygen and carbon dioxide ventilatory equivalents were significantly lower by 9% and 8% respectively. Review of the stage-by-stage responses" to the treadmill test between the laboratory valve and respirator/canister conditions indicated no significant differences (NS) in oxygen uptake but slightly lower heart rates (NS). Ventilation was not influenced by the canisters until 80% of VO2 m a x , at which time the mean oxygen ventilatory equivalent became significantly lower. Blood lactate was significantly depressed between 60% and 90% VO2 max under the respiratory/canister conditions. It was concluded that, although physiological adaptation occurred, breathing with the new CB respirator and each of the three purifying canisters had no detrimental effect on progressive aerobic work to exhaustion. However, prolonged work at intensities greater than 8 0 - 8 5 % of VO 2 max would in all probability be impaired when breathing with the CB mask and the canisters.
Applied Ergonomics April 1991
137