Deep body core temperatures in industrial workers under thermal stress

To date, no field study has continuously monitored the deep body core temperatures of industrial workers. A program to continuously measure deep body core temperatures in 36 industrial workers working 10-, 12-, and 12.5-hour day and nightshifts in a hot, deep, underground mine in the Tropics was conducted. No heat illness occurred in these workers during the study. Miniaturized radio-transponders ("pills") taken orally were used to measure temperature during the transit time in the gastrointestinal tract. Commonly recommended limits for industrial hyperthermia are 38.0 degrees C, or an increase of +1 degree C. The results showed that miners regularly exceeded these limits in terms of maximum deep body core temperature (average, 38.3 degrees C; standard deviation, 0.4 degree C), maximum temperature rise (1.4 degrees C, 0.4 degree C), and maximum heat storage (431 kJ, 163 kJ) without reporting any symptoms of heat illness. A significant component of the observed elevated core temperatures was attributable to the normal circadian rhythm, which was measured at 0.9 degree C (standard deviation, 0.2 degree C). Evidence was found that workers "self-pace" when under thermal stress.     

Comparison of estimated core body temperature measured with the BioHarness and rectal temperature under several heat stress conditions

Monitoring and measuring core body temperature is important to prevent or minimize physiological strain and cognitive dysfunction for workers such as first responders (e.g., firefighters) and military personnel. The purpose of this study is to compare estimated core body temperature (Tco-est), determined by heart rate (HR) data from a wearable chest strap physiology monitor, to standard rectal thermometry (Tre) under different conditions.

?Tco-est and Tre measurements were obtained in thermoneutral and heat stress conditions (high temperature and relative humidity) during four different experiments including treadmill exercise, cycling exercise, passive heat stress, and treadmill exercise while wearing personal protective equipment (PPE).

?Overall, the mean Tco-est did not differ significantly from Tre across the four conditions. During exercise at low-moderate work rates under heat stress conditions, Tco-est was consistently higher than Tre at all-time points. Tco-est underestimated temperature compared to Tre at rest in heat stress conditions and at a low work rate under heat stress while wearing PPE. The mean differences between the two measurements ranged from ?0.1 ± 0.4 to 0.3 ± 0.4°C and Tco-est correlated well with HR (r = 0.795 – 0.849) and mean body temperature (r = 0.637 – 0.861).

?These results indicate that, the comparison of Tco-est to Tre may result in over- or underestimation which could possibly lead to heat-related illness during monitoring in certain conditions. Modifications to the current algorithm should be considered to address such issues.     

Heat stress and strain in an aluminum smelter.

Studies of worker heat stress and strain in aluminum smelters have found that heat exposure likely to exceed the American Conference of Governmental Industrial Hygienists' threshold limit value (TLV) and that the dose-response relationship between heat stress and strain was weak. A heat stress model based on climatic data and a task analysis indicated exposures to heat stress in excess of the TLV during the July/August study period. To study the impact of working above the TLV, heat strain data (i.e., oral temperature, recovery heart rate, average heart rate) were collected. Recovery heart rates indicated high strain most of the time, and oral temperatures after peak demands were above the no-strain threshold of 37.5 degrees C about a quarter of the time, indicating that heat stress had an effect. About 95% of the readings were below 38.0 degrees C, the acute oral temperature threshold for a safe exposure. Average heart rates over 6- and 12-hour intervals were generally below acceptable limits of 120 and 110 bpm, respectively. Oral temperature and average heart rates indicated good control of heat stress exposures. Because recovery heart rates were high, some employees were working near their individual limits. The dose-response relationship for recovery heart rate and oral temperature were examined against the level of heat stress above the TLV. There was no relationship between oral temperature and heat stress level. There was an apparent trend toward higher recovery heart rates with heat stress. The lack of a dose-response relationship may be explained by brief periods of very high wet bulb globe temperatures that drove the time-weighted average up out of proportion to the physiological response.     

Prediction of rectal temperature by the Questemp II personal heat strain monitor under low and moderate heat stress

This study assessed the use of aural canal temperature measured with the Questemp II personal heat strain monitor (Tq) relative to rectal temperature (Tre) during simulated industrial work in three different wet bulb globe temperatures (WBGT). Sixteen subjects performed walking and arm curl exercise at a rate of 300 kcal/hour for 4 hours while wearing Saranex protective coveralls in 18, 23, and 27 degrees C WBGT environments and wearing the Questemp II. Correlations were determined between Tre and Tq for the three conditions and for all conditions combined. Pearson r values were 0.48 (18 degrees C WBGT), 0.42 (23 degrees C WBGT), 0.38 (27 degrees WBGT), and 0.50 (all trials). Because a major concern is safe maximum core body temperature, means and standard deviations for differences between Tre and Tq were assessed at peak temperatures to determine the predictability of Tre from Tq solely at these points. Large standard deviations in delta values relative to a small overall tolerable temperature range ruled out the use of Tq in this manner. Based on the current data, aural canal temperature as measured with the Questemp II did not provide an accurate reflection of Tre across time nor at peak core temperatures during low to moderate heat strain.     

A comparison of physiological responses to two types of particle barrier, vapor permeable clothing ensembles.

Chemical protective clothing (PC) use while working results in elevated rectal temperatures (Tre) that limit work time. Particle barrier, vapor permeable (PBVP) PCs allow workers to cool themselves by evaporating some sweat. The purpose of this study was to compare the effects on worker productivity of two types of PBVP suits, a Kleenguard (PPPC) (Kimberly Clark), and a Tyvek (PEPC) (DuPont) suit. Fifteen males in a repeated measures design performed four work tests consisting of a walk/arm curl combination at a time-weighted work rate of 1.0 L/min (300 kcal/hr), two in a wet bulb globe temperature (WBGT) of 26 degrees C and two in a WBGT of 18 degrees C, with subjects wearing each suit once in each environment. No significant difference (p > 0.05) was observed between the suits at 18 degrees C WBGT, but a significant difference was found (p < 0.05) between the suits, with the PPPC having a lower Tre in the WBGT = 26 degrees C at the 80th, 100th, and 120th min. A significant difference (p < .05) was also seen in the 26 degrees C WBGT with the PPPC resulting in a lower heart rate (HR) at the 40th, 60th, 80th, 100th, and 120th min and rate of perceived exertion (RPE) at the 75th, 90th, and 120th min. Additionally, a significant difference (p < .05) was seen between PEPC and PPPC for Tre, delta Tre, mean skin temp (mTsk), delta mTsk, and HR, each regressed against time in the 26 degrees C WBGT. Twelve of the 15 subjects also reported feeling cooler in the PPPC versus the PEPC in either WBGT environment.     

The management of heat stress for the firefighter: a review of work conducted on behalf of the Toronto Fire Service

This report provides a summary of research conducted through a grant provided by the Workplace Safety Insurance Board of Ontario. The research was divided into two phases; first, to define safe work limits for firefighters wearing their protective clothing and working in warm environments; and, the second, to examine strategies to reduce the thermal burden and extend the operational effectiveness of the firefighter. For the first phase, subjects wore their protective ensemble and carried their self-contained breathing apparatus (SCBA) and performed very light, light, moderate or heavy work at 25 degrees C, 30 degrees C or 35 degrees C. Thermal and evaporative resistance coefficients were obtained from thermal manikin testing that allowed the human physiological responses to be compared with modeled data. Predicted continuous work times were then generated using a heat strain model that established limits for increases in body temperature to 38.0 degrees C, 38.5 degrees C and 39.0 degrees C. Three experiments were conducted for the second phase of the project. The first study revealed that replacing the duty uniform pants that are worn under the bunker pants with shorts reduced the thermal strain for activities that lasted longer than 60 min. The second study examined the importance of fluid replacement. The data revealed that fluid replacement equivalent to at least 65% of the sweat lost increased exposure time by 15% compared with no fluid replacement. The last experiment compared active and passive cooling. Both the use of a mister or forearm and hand submersion in cool water significantly increased exposure time compared with passive cooling that involved only removing most of the protective clothing. Forearm and hand submersion proved to be most effective and produced dramatic increases in exposure time that approximated 65% compared with the passive cooling procedure. When the condition of no fluid replacement and passive cooling was compared with fluid replacement and forearm and hand submersion, exposure times were effectively doubled with the latter condition. The heat stress wheel that was generated can be used by Commanders to determine safe work limits for their firefighters during activities that involve wearing their protective clothing and carrying their SCBA.     

Psychrometric limits to prolonged work in protective clothing ensembles

When work is performed by workers in protective clothing, sweat evaporation is limited and body temperature rises. In an attempt to quantify the limits such ensembles place on safe work, 6 acclimated men and women walked at 30% VO2max (150-200 W/m2) in 2 protocols involving environmental transients. In one, ambient water vapor pressure (Pw) was fixed at 10 torr, and after rectal temperature (Tre) plateaued, ambient dry-bulb temperature (Tdb) was raised 2 degrees C every 10 min. In the second, Tdb was constant and Pw was increased 2 torr every 10 min. Critical temperature (Tcrit) and pressure (Pcrit) were defined as the Tdb or Pw at which thermal balance could no longer be maintained and Tre rose sharply. Each test was performed in various clothing ensembles ranging from light cotton work clothes to "impermeable" suits. Lines connecting mean Tcrit and mean Pcrit define a limit for safe prolonged exposure/exercise for approximately 50% of the population in each ensemble. Similar lines, drawn to represent values 2 standard deviations below the mean, should provide critical environmental limits for 95% of the population.     

Maximal tachycardia and high cardiac strain during night shifts of emergency physicians

Purpose

To compare tachycardia and cardiac strain between 24-hour shifts (24hS) and 14-hour night shifts (14hS) in emergency physicians (EPs), and to investigate key factors influencing tachycardia and cardiac strain.

Methods

We monitored heart rate (HR) with Holter-ECG in a shift-randomized trial comparing a 24hS, a 14hS, and a control day, within a potential for 19 EPs. We also measured 24-h HR the third day (D3) after both shifts. We measured perceived stress by visual analog scale and the number of life-and-death emergencies.

Results

The 17 EPs completing the whole protocol reached maximal HR (180.9?±?6.9 bpm) during both shifts. Minutes of tachycardia?>100 bpm were higher in 24hS (208.3?±?63.8) than in any other days (14hS: 142.3?±?36.9; D3/14hS: 64.8?±?31.4; D3/24hS: 57.6?±?19.1; control day: 39.2?±?11.6 min, p?<?.05). Shifts induced a cardiac strain twice higher than in days not involving patients contact. Each life-and-death emergency enhanced 26 min of tachycardia?≥100 bpm (p?<?.001), 7 min?≥?110 bpm (p?<?.001), 2 min?≥?120 bpm (p?<?.001) and 19 min of cardiac strain?≥30% (p?=?.014). Stress was associated with greater duration of tachycardia?≥100, 110 and 120 bpm, and of cardiac strain?≥30% (p?<?.001).

Conclusion

We demonstrated several incidences of maximal HR during shifts combined with a high cardiac strain. Duration of tachycardia were the highest in 24hS and lasted several hours. Such values are comparable to those of workers exposed to high physical demanding tasks or heat. Therefore, we suggest that EPs limit their exposure to 24hS. We, furthermore, demonstrated benefits of HR monitoring for identifying stressful events. ClinicalTrials.gov identifier: NCT01874704.

     

Heat Exposure Standards and Women's Work

Although there is an abundant literature on the health effects of occupational heat exposure, very few authors have addressed the question of the effects of heat stress on women workers. Knowledge about the effects of work in hot environments is mainly derived from the study of "heavy" muscular activity and current heat exposure standards are based on an energy criterion according to metabolic load. Metabolic load does not reflect cardiac strain associated with sedentary, repetitive work, involving static effort. The research presented here was conducted in an industrial laundry with 11 women mangle operators exposed to moderate heat stress during the summer months and whose work activity is classified as light on the basis of energy expenditure. Physiological and symptomatological responses, work activity and ambient temperature were assessed over 3 complete work days in summer and in winter. Recorded and perceived temperature, discomfort, feelings of fatigue and symptoms of thermal stress were significantly higher in summer than in winter. Symptoms of drowsiness and musculo-skeletal aches were reported equally in both seasons. Heart rate was high in both seasons, as were calculated indices of cardiac strain. Rccommended limits for cardiac strain were surpassed significantly more often in summer than in winter. It is suggested that threshold levels should be redefined to include the prevention of cardiac strain resulting from cumulative effects of heat stress and sedentary, repetitive activity, typical of many women's job with low energy requirement.     

Heat exposure standards and women's work: equitable or debatable?

Although there is an abundant literature on the health effects of occupational heat exposure, very few authors have addressed the question of the effects of heat stress on women workers. Knowledge about the effects of work in hot environments is mainly derived from the study of "heavy" muscular activity and current heat exposure standards are based on an energy criterion according to metabolic load. Metabolic load does not reflect cardiac strain associated with sedentary, repetitive work, involving static effort. The research presented here was conducted in an industrial laundry with 11 women mangle operators exposed to moderate heat stress during the summer months and whose work activity is classified as light on the basis of energy expenditure. Physiological and symptomatological responses, work activity and ambient temperature were assessed over 3 complete work days in summer and in winter. Recorded and perceived temperature, discomfort, feelings of fatigue and symptoms of thermal stress were significantly higher in summer than in winter. Symptoms of drowsiness and musculo-skeletal aches were reported equally in both seasons. Heart rate was high in both seasons, as were calculated indices of cardiac strain. Recommended limits for cardiac strain were surpassed significantly more often in summer than in winter. It is suggested that threshold levels should be redefined to include the prevention of cardiac strain resulting from cumulative effects of heat stress and sedentary, repetitive activity, typical of many women's job with low energy requirement.     

Circulatory and thermal responses of men with different training status to prolonged physical work in dry and humid heat

Eight physically trained and eight untrained, unacclimated men walked on a treadmill at 30% of their maximum oxygen consumption up to 3.5 h in a thermoneutral [20 degrees C/40% relative humidity (RH)], a warm humid (30 degrees C/80% RH), and a hot dry (40 degrees C/20% RH) environment while wearing industrial work clothing. Their oxygen consumption, rectal and skin temperatures, sweating, cardiac output, heart rate, stroke volume, and peripheral blood pressure were measured during the tests. Thirteen of the 32 heat stress tests were prematurely stopped due to high rectal temperature, high heart rate, subjective fatigue, or heat syncope. The physiological strain, as indicated by the rectal temperature and heart rate, was not significantly different between the warm humid and hot dry environments (wet bulb globe temperature approximately 28 degrees C). The rectal temperature and heart rate responses of the physically trained and untrained subjects did not differ in any of the environments. In the heat, the heart rate was significantly higher than in the thermoneutral environment, but because of the markedly reduced stroke volume the average cardiac output was not different between the three environments. The impaired work performance in the heat seemed mainly to be related to the circulatory instability accompanying the increased cutaneous circulation.     

Relationship between physique and rectal temperature cooling rate.

Despite many attempts to relate components of physique to core temperature cooling rate, no consistent relationship has emerged. The inconsistencies among the reported findings may arise from unaccounted thermoregulatory responses or incomplete physique assessment or both. A study was designed to examine this relationship in the range of rectal temperatures (Tre) within which shivering and sweating are absent, defined as the null zone, thus minimizing the contribution of these effector responses. Twenty healthy subjects (10 male and 10 female), representing a variety of physiques, participated in the study. The anthropometric protocol included 5 heights, body mass, 8 skinfolds, 10 girths, and 4 breadths. This permitted derivation of a body surface-area-to-mass ratio and estimates of adipose and muscle tissue masses using a cadaver-validated mass fractionation model. Subjects were heated in a 40 degrees C bath followed immediately by cooling in a 30.6 degrees C bath. During the cooling, forehead sweating rate and oxygen uptake were monitored to establish the boundaries of the Tre null zone. In addition, on-line recordings were made of Tre, skin temperature, and surface heat flux at six sites. The rate of cooling of Tre (Tre), in the range of temperatures between thresholds for sweating and shivering, was correlated to the components of physique. Estimates of adipose and skeletal muscle tissue masses did not correlate to Tre in the range of core temperatures investigated. However, total mass exhibited a significant correlation (r = 0.5, P less than or equal to 0.05) with Tre, but gender seemed to distort this relationship, possibly due to differences in adipose tissue distribution.     

Musculoskeletal disorders in industrial workers of Delhi

To study the musculoskeletal disorders in industrial workers in Delhi, 631 workers from 60 factories representing small and medium-sized enterprises located in Delhi were interviewed. Many (59.4%) of the workers had musculoskeletal disorders. Tailors, those working near furnaces, cooks, workers in buffing, checking and assembly work, and those working with chemicals had the most joint complaints. Cervical pain was more frequent in tailoring and packing work, whereas lumbar pain was more common in buffing, operators working on presses, those using hand and power tools, and those lifting heavy manual loads. Contract workers had less musculoskeletal morbidity than regular and temporary workers. Skilled workers also had less morbidity. Workers experiencing more job satisfaction reported fewer musculoskeletal disorders. The high prevalence of musculoskeletal disorders in workers needs urgent attention from the health and labor sectors. An ergonomic approach to prevention should be considered. The current manual load handling limits prescribed in the Indian Factory Rules potentially expose workers to back stress. It is also inappropriate to have separate load-lifting limits for men and women. Research is urgently required to determine the safe load handling limits for the Indian working population based on ergonomic principles. Until internationally acceptable safe limits are established, back pain should be a notifiable disease in India.     

The effects of work environments on thermal strain on workers in commercial kitchens

The purpose of this study was to clarify the effect of working environments of different kinds of commercial kitchens on the thermal strain of kitchen workers. This study design was cross-sectional study, and data collection was performed during busy time in commercial kitchen from August to September 2006. The research subjects were 8 institutions, involving 7 cookers, and 16 men. Measured environmental variables were air temperature, radiant heat index, wet bulb globe thermometer index (WBGT) in front of the cookers, ambient temperature, and estimated ambient WBGT around the workers. The thermal strain on workers was evaluated by fluid loss, body temperatures, heart rate and amount of physical activity (METs). All average estimated ambient WBGTs in front of cookers were less than 27.5℃. The average heart rate was 107 ± 10 bpm, and average METs was 2.0 ± 0.6. The peak values of upper arm skin temperature and auditory canal temperature were less than 37.5℃. The work environments were affected by the kitchen spaces, cooling devices, heating methods, and heat sources. Even in the midsummer, if environmental temperatures were controlled adequately, estimated ambient WBGTs around workers were below the occupational exposure limit. Work environments and thermal strain on workers in commercial kitchen were not severe.     

Musculoskeletal Discorders in Industrial Workers of Delhi

Abstract

To study the musculoskeletal disorders in industrial workers in Delhi, 631 workers from 60 factories representing small and medium-sized enterprises located in Delhi were interviewed. Many (59.4%) of the workers had musculoskeletal disorders. Tailors, those working near furnaces, cooks, workers in buffing, checking and assembly work, and those working with chemicals had the most joint complaints. Cervical pain was more frequent in tailoring and packing work, whereas lumbar pain was more common in buffing, operators working on presses, those using hand and power tools, and those lifting heavy manual loads. Contract workers had less musculoskeletal morbidity than regular and temporary workers. Skilled workers also had less morbidity. Workers experiencing more job satisfaction reported fewer musculoskeletal disorders. The high prevalence of musculoskeletal disorders in workers needs urgent attention from the health and labor sectors. An ergonomic approach to prevention should be considered. The current manual load handling limits prescribed in the Indian Factory Rules potentially expose workers to back stress.It is also inappropriate to have separate load-lifting limits for men and women. Research is urgently required to determine the safe load handling limits for the Indian working population based on ergonomic principles. Until internationally acceptable safe limits are established, back pain should be a notifiable diseasein India.     

Dyslipidemia in industrial workers in hot environments

The aim of the study was to follow the rate and manifestation of dyslipidemia in industrial workers exposed to heat. One hundred and two male industrial workers exposed to heat and a control group of 102 male workers were studied. The microclimate components were followed and Wet Bulb Globe Temperature (WBGT) was calculated. The mean WGBT was 35.4 degrees C (28.4-41.7 degrees C) for the studied heat exposed work places. The lipid indices: total cholesterol (TC), high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C) and triacylglycerols were assayed with enzymatic tests. TC/HDL-C ratio was calculated, too. Arterial pressure, anthropometric variables, smoking, alcohol use were followed and no significant differences between the studied groups were found. Significantly higher TC, LDL-C and TC/HDL-C were found with the heat exposed industrial workers. Odds ratio indicated higher risk in heat exposed industrial workers of becoming dyslipidemic [for TC OR = 1.481 (1.097-2.002) and for LDL-C OR = 1.539 (1,123-2.111)]. Regular screening of lipid profile in heat exposed workers is recommended.     

Wet-bulb globe temperature index: a predictor of physiological strain in hot environments.

The readings of the natural wet-bulb (tnwb) and globe thermometer for computing Twbg index (indoors) were taken between 08.00 to 17.00 h at two-hour intervals in different work locations in the glass bangle and brassware industries. For assessing the physiological reliability of the Twbg index for heat stress, the radial pulse rate was monitored at two-hour intervals in 60 brassware workers and 77 glass bangle workers (mean ages: 25.3 +/- 8.8 and 28.1 +/- 5.7 years) belonging to various occupations exposed to thermal radiation for 9.3 +/- 8.5 and 11.2 +/- 4.8 years respectively. The mean values of Twbg index observed in the brassware and glass bangle industries were found to be almost of the same order (34.4 +/- 3.0 degrees C and 35.2 +/- 1.1 degrees C). The radiant heat seemed to make the most significant contribution to the environmental heat stress in these industries. The globe temperature near the main melting furnace was as high as 53.8 +/- 3.0 degrees C and 59.2 +/- 4.02 0C in the glass bangle and brassware industries respectively. It was, therefore, expected that the exposed workers would show pronounced physiological strain. Surprisingly the pulse rates of these workers did not indicate any significant physiological strain since the maximal pulse rates recorded did not exceed the safe limits of circulatory strain recommended by the WHO.(ABSTRACT TRUNCATED AT 250 WORDS)     

Heat stress evaluation and worker fatigue in a steel plant

This study assessed fatigue in electric arc melting workers (ER) and continuous casting workers (CC) in a steel plant and evaluated their physiological response to different levels of heat stress. Fifty-five men participated in the study. The ER group (mean, standard deviation [SD]=41.6, 7.4 years) was significantly older than the CC group (34.9, 6.4 years). The wet bulb globe temperature (WBGT) index of the workplace was measured. Workers' subjective fatigue symptoms were investigated by a 30-item constructive questionnaire, and physiological conditions and response time were measured before and after work for 2 consecutive days. WBGT ranged from 25.4 approximately 28.7 degrees C and 30.0 approximately 33.2 degrees C for the CC and ER areas, respectively. After age adjustment the ER group had significantly higher prevalence rates in subjective symptoms and slower response time than the CC group. The response "thirsty" was the highest after work (75 and 60% for the 2 ER interview days, respectively). A high prevalence (over 40%) of "eyes feel strained," "perception of shoulders stiff," or "feel waist pain" also was observed. Average pre- and postwork ER group systolic pressures were 129.1+/-11.4 mmHg (mean+/-SD) and 126.1+/-12.1 mmHg, 132.5+/-11.4 and 130.6+/-11.2 mmHg for the CC group. Continuous heat-strain monitoring data from one ER and one CC worker indicated that average working heart rate and body temperature were well below 150 beats/min and 38 degrees C. Faster response in critical flicker fusion was found after work than before work, but the differences were not statistically significant (p>.05). Response time for the falling bar grasp was faster at the beginning of work, declined with working time, and rebounded at the end of work. Workers exposed to a hot environment are inclined to subjective fatigue, and their fatigue symptoms increase with the heat exposure levels. However, low resting heart rate and systolic pressure are two characteristics for high heat exposure workers.     

防护水平状态和运动负荷对人员热应激反应的影响

在一个模拟热环境中，试验研究了不同防护水平和运动负荷条件下人员生理热应激反应的特点和规律。受试者为６名健康男性青年，每人均需完成各种条件下的６次热负荷试验。三种防护水平为佩戴防毒面具、穿着防毒服和着佩全身防护装具；中、重两种运动负荷相应的跑台速度、坡度分别为１．１１ｍ／ｓ、５％和１．３９ｍ／ｓ、５％，相应的试验持续时间分别为６０和４５ｍｉｎ。测试的生理指标包括肛温、皮温、心率、出汗率和汗蒸发率等。试验结果表明：防护水平和运动负荷对人员的心率反应、肛温和皮温的增加速率、以及出汗率等都有显著影响；在两种运动负荷条件下，受试者的汗蒸发率能力依防毒面具、防毒服和全身防护着装状态依次降低。因此，防护着装对汗液蒸发能力的限制、以及运动所致代谢产热的增加都是加剧人员热应激反应的重要因素。本文结果为特殊作业人员的卫生安全监护提供了试验依据     

Effect of wearing gloves on the thermal balance of Korean women wet-suit divers in cold water

Effect of wearing neoprene gloves on the thermal exchanges of wet-suited divers was studied in 8 Korean diving women. Subjects, clad with 5-6-mm-thick neoprene wet suits (jacket, pants, and boots) either with or without wearing 3-mm-thick neoprene gloves, were immersed for 3 h in water of critical temperature (17.3 degrees +/- 0.8 degree C) while the rectal and skin (chest, leg, arm, and hand) temperatures and oxygen consumption were measured. Overall thermal insulation of the subject plus suit was calculated from the rectal-to-water temperature difference divided by the estimated rate of skin heat loss. The skin heat loss was assumed to equal metabolic heat production minus respiratory heat loss, corrected for changes in heat storage when mean body temperature changed. All measurements were carried out in a resting condition. During the 3rd h of immersion, the rectal temperature was lower with gloves (delta Tre = 0.30 degree +/- 0.04 degree C; P less than 0.05) whereas metabolic heat production was not significantly different. Consequently, the total thermal insulation was nearly 16% lower with gloves than without gloves. In both the hands and forearms, the regional heat flux determined directly using a heat flux transducer was higher and the thermal insulation index was lower with gloves than without gloves. These results indicate that in wet-suited subjects resting in cold (17 degrees C) water gloves do not provide additional protection against heat loss, but rather decrease the efficiency of thermoregulatory mechanisms. We suggest that sensory input from cold receptors in the distal extremities is particularly important in thermoregulation during immersion in cold water.