Workers In Hot Environments Research Articles

Comparing thermal strain in outdoor maintenance and indoor service workers in the mining industry during summer.

While working in the heat is a common practice within the Australian mining industry, it can lead to adverse effects on cognitive function, productivity, and physical health. This study aimed to compare the thermal strain experienced by maintenance workers and service workers in the mining industry during summer. Psycho-physiological parameters, manual dexterity, and cognitive function were assessed in maintenance workers (n = 12) and service workers (n = 12) employed at mine site villages in north-west Australia. Maintenance workers had the freedom to self-select their work intensity and predominantly worked outdoors (33.9±4.2°C, 38±18% RH), whereas service workers had to work to a fixed schedule and worked intermittently indoors (∼64% of work shift; 29.5±3.4°C, 48±8% RH) and outdoors (∼36%; 35.4±4.6°C, 47±21% RH). All workers underwent assessment at the beginning (day 2/3), middle (day 7/8), and end of their swing (day 13/14), at various time points throughout their 11-12 h shift. Service workers completed more steps (11282±1794 vs. 7774±2821; p<0.001), experienced a higher heart rate (p = 0.049) and reported higher ratings of perceived exertion (p<0.001), thermal discomfort (p<0.001), thermal sensation (p<0.001), and fatigue (p<0.012) compared to maintenance workers. Urinary specific gravity values were higher (less hydrated) in service workers (1.024±0.007) compared to maintenance workers (1.018±0.006; p = 0.007), with USG being overall higher post- compared to pre-shift (1.022±0.008 vs. 1.020±0.006; p<0.05). Core temperature, working memory capacity, processing speed and manual dexterity did not differ between occupations. Workers in hot environments who cannot self-select their work intensity should be educated about the importance of hydration before, during, and after their work-shifts and provided with more scheduled rest breaks during their shift. Employers should closely monitor workers for symptoms of heat illness, discomfort, and fatigue to ensure the health and safety of the workers.

Modification of the Predicted Heat Strain (PHS) model in predicting human thermal responses for Chinese workers in hot environments

The Predicted Heat Strain (PHS) model predicts physiological responses of European people to heat stress; while its performance for Chinese population remains underexplored. The study conducted a heat exposure experiment (temperature: 35 °C/38 °C/40 °C, relative humidity (RH): 25%/40%/60%) in a well-controlled climate chamber. 10 male Chinese workers were recruited to perform exercises on the treadmill at a speed of 0.5 m/s for 120min, to simulate moderate metabolic rate. Rectal temperature(Tre), skin temperature(Tsk), sweat rate(SR) and heart rate(HR) were monitored continuously; the corresponding predicted values were obtained by the PHS model. The results showed that the measured Tre, Tsk, SR increased significantly with increased temperature and RH. The PHS model overestimated the maximum allowable exposure time of subjects but underestimated the final Tre and Tsk. Bland–Altman analysis showed that the differences and 95%CI between the observed and predicted values increased with increasing temperature, RH and exposure time, indicating the significant prediction deviation of the PHS model. Through adjusting the initial Tre from 36.8 °C to 37 °C, the protection efficacy was improved from original 24.7% to57.1% for the PHS model. The protection efficacies were further improved to 71.2% through adjusting the maximum HR based on ages, and to 68.2% through adopting the real-time HR to predict metabolic rates. The proposed three methods improve the heat strain prediction in the PHS model for Chinese workers and are more applicable in practical hot working place. This benefits to policy decisions and occupational safety protection for Chinese workers with heat exposure risks.

An optimal two-bout strategy with phase change material cooling vests to improve comfort in hot environment

Cooling vests incorporating phase change material (PCM) packets are used to improve comfort of workers in hot environments. This work aims to investigate by modeling and experimentation the effect of dividing the working duration into two bouts, where different PCM melting temperatures are used in each bout. An integrated bio-heat and fabric-PCM model predictions of physiological and subjective votes are validated via active human subject testing at hot conditions. A parametric study is performed to select, at two conditions (40°C and 45°C), the optimal PCM melting temperatures of the two bouts that would result with similar thermal comfort and sensation to the optimal single-bout case. The optimal case achieves most reductions in energy use for PCM regeneration, PCM carried weight and material cost.The results of the parametric study showed that heat storage is reduced in the second bout due to wearing the second vest with lower PCM melting temperature, thus thermal comfort and sensation are significantly improved. The optimal case at the 40°C environment uses a vest with 21°C PCMs in the first bout and a vest with 21°C PCMs in the second bout (V21→V21). At 45°C, the optimal case is V18→V10 with significant PCM weight reductions from the reference single bout case by a minimum of 47%. Thus, the issue of extra carried weight that affect metabolism and ease of movement when applying continuous cooling during work have been mitigated by using the two-bout strategy.

Validity of Infrared Tympanic Temperature for the Evaluation of Heat Strain While Wearing Impermeable Protective Clothing in Hot Environments

The purpose of this study was to investigate the validity of infrared tympanic temperature (IR T(ty)) as a thermal index to evaluate the heat strain of workers in hot environments, in comparison with rectal temperatures at various depths (T(re-4, -8, and -16) for 4, 8 and 16 cm from the anal sphincter). Eight males underwent twelve experimental conditions: two activities (rest and exercise) × three clothing levels [Control, HDPE (high-density polyethylene coverall) and PVC (polyvinyl chloride coverall) condition] × two air temperatures (25 and 32℃ with 50%RH). The results showed that 1) in the conditions with most heat strain (HDPE or PVC condition at 32℃), IR T(ty) was equal to or even higher than T(re); 2) during exercise, physiological strain index (PSI) using IR T(ty) did not underestimate PSI-values using T(re-16), and overestimated those PSI-values from T(re-16) in HDPE and PVC conditions at 32℃; 3) during exercise, the relationships between IR T(ty) and heart and total sweat rate were stronger than those between T(re-16) and heart and total sweat rate. These results indicated that IR T(ty) is valid as a thermal index to evaluate the heat strain of workers wearing impermeable protective coveralls in hot environments. However, the application of IR T(ty) is limited only for strenuous works wearing encapsulated personal protective clothing with a hood in heat.

Pesticides and Other Chemicals: Minimizing Worker Exposures

ABSTRACT Pesticides, ammonia, and sanitizers, all used in agricultural production present ongoing risks for exposed workers. Pesticides continue to poison workers despite elimination of some of the most toxic older products. Obligatory reporting of pesticide poisonings exists in 30 states and surveillance of poisoning occurs in only 12. Estimates of poisoning numbers have been based on sampling but funding for this is scant and in constant jeopardy. There appears to be a downward trend in poisonings nationally based on SENSOR data. Newer more pest-specific pesticides are generally less toxic and present less health risks but may have unpredicted health effects in humans that may not emerge until used widely. Internationally, older cheaper chemicals continue to be used with serious consequences in many developing countries. Monitoring workers for overexposure to pesticides broadly is impractical with the exception of the cholinesterase inhibitors. We can learn much from monitoring systems. Unfortunately, monitoring tools are economically inaccessible for most other chemical groups. New technologies for toxicity testing will necessitate new biomonitoring tools that should be supplied by the producers of these chemicals and made available for protecting worker and the public. Protection of workers from pesticides is primarily based on personal protective equipment use, which presents significant hardship for workers in hot environments and is generally considered the least effective approach on the hierarchy of controls in worker protection. Isolation through the use of closed systems has been employed, though rarely studied as to effectiveness in field use. Substitution or replacing harmful substances with safer ones is underway as more pest specific chemicals enter the pesticide portfolio and older ones drop out. This paper summarizes the panel presentation, “Minimizing Exposures to Pesticides and Other Chemicals,” at the Agricultural Safety and Health Council of America/National Institute for Occupational Safety and Health conference, “Be Safe, Be Profitable: Protecting Workers in Agriculture,” Dallas/Fort Worth, Texas, January 27–28, 2010. The panel presented several different aspects of agrochemicals and health. The discussion aimed at identifying important practical opportunities to begin to decrease agricultural worker overexposure.

Evaluation of a Carbon Dioxide Personal Cooling Device for Workers in Hot Environments

This study tested the effectiveness of a carbon dioxide cooling device in reducing heat strain for workers in a hot and humid environment. Ten participants completed two trials in an environment of 30°C WBGT (75% relative humidity) with a novel liquid carbon dioxide cooling shirt (CC) or no cooling (NC) in a randomized order. Mean time-weighted workload for each individual equaled 465 W (400 Kcals· h−1). In the CC condition, the work time was significantly increased by 32% (97 ± 36 min) compared with NC (74 ± 26 min) (p < 0.05). There was no significant difference in mean skin temperature over the trials. Rectal temperature (T re ) was significantly different after 50 min (p < 0.05). Mean heart rate, the delta T re increase rate, and heat storage at 55 min (last point with n = 8) were significantly lower in CC (p < 0.05). Overall heat storage was 54 ± 41 W and 72 ± 40 W for CC and NC, respectively (p < 0.05). Participants also indicated favorable subjective responses for CC vs. NC (p < 0.05). These findings suggest that this novel cooling device would effectively attenuate heat strain and increase work productivity for personnel working in a hot and humid environment. Practical aspects of use such as cost, convenience, weight, cooling duration, and rise in ambient CO2 concentration in confined spaces must also be considered.

Evaluation of a Novel Personal Cooling Device for Workers in Hot Environments

Heat strain from the environment and clothing poses a serious threat in many occupational settings. Many personal cooling devices are limited in field use due to lack of mobility, limited cooling capacity, logistics, cost, and other factors. A non-powered cooling garment based on the endothermic expansion of liquefied carbon dioxide (CO2) has recently been developed. PURPOSE: To determine the effectiveness of this novel cooling device in reducing heat strain during work in a hot and humid environment. METHODS: Ten males completed two trials in an environment of 30°C WBGT (75% relative humidity) with a novel liquid carbon dioxide cooling shirt (CC) or with no cooling (NC) in a randomized order. Mean time-weighted workload of walking and arm curls for each individual equaled 465 W (400 Kcals/h). RESULTS: In the CC condition, work duration was significantly increased by 32% (97±36 min) compared to NC (74±26 min) (p<0.05). There was no significant difference between CC and NC for mean skin temperature across trials. The rectal temperature (Tre) was significantly lower for CC after 50 min (p<0.05). The mean heart rate, the delta Tre increase rate, and heat storage at 55 min (last point with n=8) were significantly lower in CC (p<0.05). Overall heat storage was 54±41 W (CC) and 72±40 W (NC) (p<0.05). Participants also indicated favorable subjective responses (comfort, etc.) for CC vs. NC (p<0.05). CONCLUSION: This novel cooling device attenuated heat strain and would increase productivity for personnel working in a hot and humid environment. Practical aspects of use, such as: cost, convenience, weight, cooling duration, and rise in ambient CO2 concentration in confined spaces, must also be considered. Support by a Grant from Kimberly-Clark and Porticool, Inc.

Climate change, direct heat exposure, health and well-being in low and middle-income countries

Climate change, direct heat exposure, health and well-being in low and middle-income countries

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.

International Standards for the Assessment of the Risk of Thermal Strain on Clothed Workers in Hot Environments: Comment

International Standards for the Assessment of the Risk of Thermal Strain on Clothed Workers in Hot Environments: Comment

International Standards for the Assessment of the Risk of Thermal Strain on Clothed Workers in Hot Environments: Reply

International Standards for the Assessment of the Risk of Thermal Strain on Clothed Workers in Hot Environments: Reply

International standards for the assessment of the risk of thermal strain on clothed workers in hot environments

The International Standards Organisation (ISO) has produced an integrated series of international standards for the assessment of human responses to thermal environments. They include standards for the assessment of thermal comfort, heat stress and cold stress and many have been adopted as European and British standards. This paper describes the series of standards and in particular those concerned with the assessment of risk in hot environments. A three tier approach is taken which involves a simple thermal index that can be used for monitoring and control of hot environments (ISO 7243), a rational approach which involves an analysis of the heat exchange between a worker and his or her environment (ISO 7933) and a standard that describes the principles of physiological measurement which can be used in the establishment of personal monitoring systems of workers exposed to hot environments (ISO 9886). The standards are self-contained and can be used independently. In any comprehensive assessment however they would be used in conjunction. The simple index provides a first stage analysis and can confirm whether or not there is likely to be unacceptable thermal strain. Where a more detailed analysis is required then ISO 7933 provides an analytical method that can provide a more extensive assessment and interpretation leading to recommendations for improvement to the working environment. Where a method needs to be confirmed, or conditions are beyond the scope of ISO 7243 and ISO 7933, then ISO 9886 provides guidance on physiological measurement and interpretation. This would be used in extreme environments where individual responses are required to ensure health and safety or, in the case where personal protective equipment (PPE) is worn, which is beyond the scope of ISO 7243 and ISO 7933. The ISO system therefore covers almost all exposures to hot environments. It would be useful however to extend the scope of the standards that provide a simple index or analytical approach. This paper describes the current standards and their scope and forms the basis and background for descriptions of proposed extensions to the scope of the standards described in other papers in this special issue.

International standards for the assessment of the risk of thermal strain on clothed workers in hot environments

The International Standards Organisation (ISO) has produced an integrated series of international standards for the assessment of human responses to thermal environments. They include standards for the assessment of thermal comfort, heat stress and cold stress and many have been adopted as European and British standards. This paper describes the series of standards and in particular those concerned with the assessment of risk in hot environments. A three tier approach is taken which involves a simple thermal index that can be used for monitoring and control of hot environments (ISO 7243), a rational approach which involves an analysis of the heat exchange between a worker and his or her environment (ISO 7933) and a standard that describes the principles of physiological measurement which can be used in the establishment of personal monitoring systems of workers exposed to hot environments (ISO 9886). The standards are self-contained and can be used independently. In any comprehensive assessment however they would be used in conjunction. The simple index provides a first stage analysis and can confirm whether or not there is likely to be unacceptable thermal strain. Where a more detailed analysis is required then ISO 7933 provides an analytical method that can provide a more extensive assessment and interpretation leading to recommendations for improvement to the working environment. Where a method needs to be confirmed, or conditions are beyond the scope of ISO 7243 and ISO 7933, then ISO 9886 provides guidance on physiological measurement and interpretation. This would be used in extreme environments where individual responses are required to ensure health and safety or, in the case where personal protective equipment (PPE) is worn, which is beyond the scope of ISO 7243 and ISO 7933. The ISO system therefore covers almost all exposures to hot environments. It would be useful however to extend the scope of the standards that provide a simple index or analytical approach. This paper describes the current standards and their scope and forms the basis and background for descriptions of proposed extensions to the scope of the standards described in other papers in this special issue.

Heat Stress

Heat cramps, heat exhaustion, and heat stroke are major disorders resulting from the body's reaction to overexposure to hot environments. Physiological and psychological adaptation to hot environments--acclimatization--can improve heat tolerance. A number of measures determine the environmental contributions to heat stress. The occupational health nurse can establish priorities for addressing the work related health needs of workers in hot environments.

Effects of Cold and Hot Stimuli on Peripheral Vascular System of Workers in Hot Environments

The static conditions of peripheral vascular systems were observed on the workers in hot environments and dynamic changes to cold and hot stimuli were also examined.Six men 22 to 27 years old engaged in hot environments for about three years were originally selected for this study, and simultaneously six clerks of the same ages were examined as a control group. They were measured before and after working in summer and winter respectively on the changes of capillary figures and pulse waves in the left fingertip skin at the room temperature, than on the changes to cold and hot stimuli (7±2°C, 49±2°C) for every ten seconds applied on the back of the same hand. The results obtained were as follows: 1) The effects of working in hot environments were not found in the width of skin capillary figures, but a tendency toward lowering after working was seen in the visible height of capillaries, especially in summer. 2) Ordinary redustions in the amplitude of pulse waves were observed after working in both seasons, but these changes were not shown as characterisitic of the hot environmental group. It is considered that the tension of peripheral blood vessels may be changed by working. 3) The chnges to cold stimuli before working were observed to be more insensitive (prolongation of the reaction time) in summer, more sensitive in winter in the hot environmental group, than that of the control group, and no significant changes were found between the both groups after working. The changes to hot stimuli before working were also observed to be more sensitive in the hot envitonmental group than that of the control group, especially in summer, but no significant difference after working was shown between the both groups. In winter, a tendency of sensitive reaction was seen in the hot environmental group after working compared with the control group, in spite of no significant difference was recognized in both groups before working. The workers engaged in hot environments are relatively stable for cold stimuli and labile for hot stimuli after working and it suggests that the acclimatized workers have been prepared to escape the heat stress in the body. 4) As a rule, the crest time shortens in winter compared with summer. The ratio of the time necessary for constriction of blood vessels to the duration of pulse waves (t/d) was lower in the hot environmental group than the control group before working, especially in summmer, but this difference was not significant between the both groups after working.