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Purpose: The current study aimed to determine the effect of a synthetic-grass sport surface on core body temperature, skin temperature, heart rate, thermal sensation, thermal comfort, and rating of perceived exertion (RPE) during intermittent exercise in hot conditions. Methods: Using a randomized crossover design, 13 trained/developmental team-sport athletes completed two 50-minute standardized intermittent running protocols on a synthetic and a natural-grass surface, on separate days (control-condition air temperature 32.6 °C [1.3 °C], relative humidity 43.2% [5.3%]). Results: Final skin temperature was significantly higher on synthetic compared with natural grass at the calf (40.1 °C [2.5 °C] vs 33.4 °C [0.6 °C]; P <.001), shoulder (36.6 °C [1.7 °C] vs 33.7 °C [0.7 °C]; P <.001), and chest (33.2 °C [1.1 °C] vs 31.8 °C [1.2 °C]; P =.02). Thermal sensation (median: 2.3; interquartile range [0.5] vs 2.2 [0.5], P =.03) and sweat rate (1.5 [0.4] L·h−1 vs 1.2 [0.3] L·h−1; P =.02) were also significantly higher on synthetic grass. While final core body temperature was significantly higher on the natural than synthetic grass (38.4 °C [0.3 °C] vs 38.2 °C [0.4 °C]), there were no significant differences in delta core temperature, as well as heart rate, thermal comfort, or RPE. Conclusions: Higher skin temperatures, thermal sensation, and sweat rates suggest that exercising on synthetic grass in hot conditions may increase some markers of heat strain during exercise. However, delta core body temperature, heart rate, thermal comfort, and RPE remained unaffected. [ABSTRACT FROM AUTHOR]

Abstract Studies on the effect of heat stress on pregnant women are scarce, particularly in highly vulnerable populations. To support the risk assessment of pregnant subsistence farmers in the West Kiang district, The Gambia we conducted a study on the pathophysiological effects of extreme heat stress and assessed the applicability of heat stress indices. From ERA5 climate reanalysis we added location-specific modelled solar radiation to datasets of a previous observational cohort study involving on-site measurements of 92 women working in the heat. Associations between physiological and environmental variables were assessed through Pearson correlation coefficient analysis, mixed effect linear models with random intercepts per participant and confirmatory composite analysis. We found Pearson correlations between r-values of 0 and 0.54, as well as independent effects of environmental variables on skin- and tympanic temperature, but not on heart rate, within a confidence interval of 98%. Pregnant women experienced stronger pathophysiological effects from heat stress in their third rather than in their second trimester. Environmental heat stress significantly altered maternal heat strain, particularly under humid conditions above a 50% relative humidity threshold, demonstrating interactive effects. Based on our results, we recommend including heat stress indices (e.g. UTCI or WBGT) in local heat-health warning systems.

Wet bulb globe temperature (WBGT) is a commonly used measure to predict heat strain in workers. Different combinations of environmental conditions can create equivalent WBGT, yet it remains unknown whether biophysical, physiological, and perceptual responses vary when working in different but equivalent hot conditions. The purpose of the study was to compare body heat storage and physiological and perceptual strain during walking in hot-dry and warm-wet conditions of the same WBGT. Twelve subjects (age: 22 ± 2 y) walked for 90 min at 60% maximum heart rate in a 27.8°C WBGT environment of hot-dry (HD: 40°C, 19% relative humidity) or warm-wet (WW: 30°C, 77% relative humidity) conditions. Partitional calorimetry was used to estimate heat storage. Core temperature at 90 min (HD: 38.5 ± 0.5°C; WW: 38.4 ± 0.3°C, p = 0.244) and cumulative heat storage (HD: 115 ± 531 Kj; WW: 333 ± 269 Kj, p = 0.242) were not different. At 90 min, heart rate was not different (HD: 160 ± 19 bpm; WW: 154 ± 15 bpm, p = 0.149) but skin temperature (HD: 36.6 ± 0.9°C; WW: 34.7 ± 0.6°C, p < 0.001), thirst (HD: 6.8 a.u.; WW: 5.3 a.u. p = 0.043), and sweat rate (HD: 15.1 ± 4.4 g·min−1; WW: 10.0 ± 4.1 g·min−1, p < 0.001) were greater in HD compared to WW. Hot environments of equivalent 27.8°C WBGT created equivalent core temperature despite differences in physiological strain during exercise, including earlier onset of cardiovascular strain, greater sweat rate, and higher skin temperature compared to a WW environment. ClinicalTrials.gov ID NCT04624919. [ABSTRACT FROM AUTHOR]

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Abstract Hijabs are predominantly worn in hot environments, but very rare studies on the thermo-physiological effects of wearing hijabs are found. We investigated the effects of wearing rayon and polyester hijabs on wearers’ physiological and subjective responses in warm-humid and hot-dry environments. Eight females (25.0 ± 2.3 y in age, 157.7 ± 4.1 cm in height, and 50.8 ± 7.5 kg in weight) participated in three conditions (No hijab, rayon hijab, and polyester hijab condition) during exercise in two thermal environments: a warm-humid (30 °C and 70%RH) and a hot-dry environment (36 °C and 30%RH), which generated an identical wet-bulb globe temperature at 27 °C. The results showed that no differences in rectal temperature were found among the three clothing conditions or the two environments, whereas auditory canal temperature was higher in the hot-dry than in the warm-humid environment (P

Abstract Background It is pertinent to understand the perceptions of healthcare workers (HCWs) with their associated personal protective equipment (PPE) usage and heat strain symptoms experienced to effectively combat the negative effects of heat stress during treatment and care activities. Methods We evaluated the associated heat stress perceived by HCWs across Asia and validated a questionnaire on perceptions of heat stress, associated PPE usage, and heat strain symptoms experienced. The questionnaire was administered to 3,082 HCWs in six Asian regions. Factor analyses, including Cronbach’s alpha, assessed the questionnaire’s validity and reliability. Structural equation modelling analysed the effects of knowledge, attitudes and practices, and heat strain symptoms. Results The questionnaire was found to be reliable in assessing HCWs’ knowledge, and attitudes and practices towards heat stress and PPE usage (both Cronbach’s alpha = 0.9), but not heat strain symptoms (Cronbach’s alpha = 0.6). Despite knowledge of heat stress, HCWs had negative attitudes and practices regarding PPE usage (β1 = 0.6, p

With climate change fueling more frequent and intense periods of hot weather, heat stress management programs are becoming increasingly important for protecting the health and safety of workers in the Canadian mining industry. While the inclusion of heat-mitigation measures such as those provided by the American College of Governmental Industrial Hygienists (ACGIH) Threshold Limit Values (TLVs) are commonly employed by industry, there is a need to develop more comprehensive industry-specific measures for heat stress prevention and management. To better understand current heat management practices and identify opportunities for improvement, an exploratory survey of 51 employees responsible for health and safety at underground mining (n = 35), and surface operations (n = 16) (e.g., open-pit mining, milling, smelting, and exploration site) was conducted in Canada. The respondents answered 50 questions related to workplace heat stress management, including descriptors of the workplace environment, perceived heat stress hazard, administration of heat stress management programming, heat stress emergency procedures, environmental monitoring strategies, and knowledge of mining-specific regulations related to heat stress. Twenty-four managers (47%) reported that heat-related illnesses led to restricted duty or lost time claims at their site, with a median of 5 [IQR: 2–10, max: 30] reportable heat-related illnesses occurring per site annually. Many also felt that heat-related illnesses are under-reported by their workforce (n = 36, 71%). Most sites reported established heat stress management programs to prevent heat illness (n = 43, 84%), typically based on the TLVs (n = 38, 75%). Although some organizations do conduct pre-task evaluations for heat stress (n = 30, 59%), more than half do not conduct post-job evaluations (n = 28, 55%) or pre-employment screening for heat stress vulnerability (n = 3, 6%). While our findings indicate that the health and safety managers recognize the hazard posed by heat and have stated practices to help address the hazard, we also observed inconsistencies in heat stress management programming across the sample. Developing and adopting a standard heat stress management and reporting system would be an important step toward protecting workers from existing and emerging threats from extreme heat and climate change. [ABSTRACT FROM AUTHOR]

Occupational heat stress increases the risk of acute kidney injury (AKI). This study presents a secondary analysis to generate novel hypotheses for future studies by investigating the diagnostic accuracy of thermal, hydration, and heart rate assessments in discriminating positive AKI risk following physical work in the heat in unacclimatized individuals. Unacclimatized participants (n = 13, 3 women, age: ∼23 years) completed four trials involving 2 h of exercise in a 39.7 ± 0.6 °C, 32 ± 3% relative humidity environment that differed by experimental manipulation of hyperthermia (i.e., cooling intervention) and dehydration (i.e., water drinking). Diagnostic accuracy was assessed via receiver operating characteristic curve analysis. Positive AKI risk was identified when the product of concentrations insulin-like growth factor binding protein 7 and tissue inhibitor of metalloproteinase-2 [IGFBP7∙TIMP-2] exceeded 0.3 (ng∙mL−1)2∙1000−1. Peak absolute core temperature had the acceptable discriminatory ability (AUC = 0.71, p = 0.009), but a relatively large variance (AUC 95% CI: 0.57–0.86). Mean body temperature, urine specific gravity, urine osmolality, peak heart rate, and the peak percent of both maximum heart rate and heart rate reserve had poor discrimination (AUC = 0.66–0.69, p ≤ 0.051). Mean skin temperature, percent change in body mass and plasma volume, and serum sodium and osmolality had no discrimination (p ≥ 0.072). A peak increase in mean skin temperature of >4.7 °C had a positive likelihood ratio of 11.0 which suggests clinical significance. These data suggest that the absolute value of peak core temperature and the increase in mean skin temperature may be valuable to pursue in future studies as a biomarker for AKI risk in unacclimatized workers. [ABSTRACT FROM AUTHOR]

The rise in heatwaves due to climate change is becoming a significant concern for outdoor workers, particularly leading to an increasing number of heat-related illnesses. To address the challenge, this study aimed to propose, as a process-based approach, a classification model using personal biometric characteristics to identify individuals who are vulnerable to extremely hot environments (i.e., high-risk groups). To this end, an experimental study was conducted, and experimental conditions were set in an environmental chamber by considering the extremely hot summer weather in Korea. With the data collected from a total of 70 people who voluntarily participated in the experiment, the classification model was developed by adopting multiple methodologies such as time-series clustering, independent samples t-test, and machine-learning algorithms. Consequently, it was found that the classification performance was the best with the multilayer perceptron algorithm, resulting in 0.800 in terms of the area under the receiver operating characteristic (AUROC) and 0.811 in terms of the area under the precision-recall curve (AUPRC). This study creates new ground in identifying individuals vulnerable to extremely hot environments in the domain of management in engineering by employing machine-learning-based classification algorithms with personal biometric characteristics. The proposed approach can be realized by utilizing a simple and low-cost bioelectrical impedance method for estimating human body composition (such as body fat mass and skeletal muscle mass) before they are put into the field. It is expected to aid in providing a more systematic and individualized management system for proactively preventing personal heat-related illnesses. [ABSTRACT FROM AUTHOR]

Background: It is pertinent to understand the perceptions of healthcare workers (HCWs) with their associated personal protective equipment (PPE) usage and heat strain symptoms experienced to effectively combat the negative effects of heat stress during treatment and care activities. Methods: We evaluated the associated heat stress perceived by HCWs across Asia and validated a questionnaire on perceptions of heat stress, associated PPE usage, and heat strain symptoms experienced. The questionnaire was administered to 3,082 HCWs in six Asian regions. Factor analyses, including Cronbach's alpha, assessed the questionnaire's validity and reliability. Structural equation modelling analysed the effects of knowledge, attitudes and practices, and heat strain symptoms. Results: The questionnaire was found to be reliable in assessing HCWs' knowledge, and attitudes and practices towards heat stress and PPE usage (both Cronbach's alpha = 0.9), but not heat strain symptoms (Cronbach's alpha = 0.6). Despite knowledge of heat stress, HCWs had negative attitudes and practices regarding PPE usage (β1 = 0.6, p < 0.001). Knowledge (path coefficient = 0.2, p < 0.001), and negative attitudes and practices (path coefficient = 0.2, p < 0.001) of HCWs towards heat stress and PPE usage adversely affected symptoms experienced. Conclusions: The questionnaire was not reliable in assessing symptoms. HCWs should, nevertheless, still self-assess their symptoms for early detection of heat strain. To effectively attenuate heat strain, understanding HCWs' attitudes and practices towards PPE usage should guide policymakers in implementing targeted heat management strategies. [ABSTRACT FROM AUTHOR]

The heat-related health burden is expected to persist and worsen in the coming years due to an aging global population and climate change. Defining the breadth and depth of our understanding of age-related changes in thermoregulation can identify underlying causes and strategies to protect vulnerable individuals from heat. We conducted the first systematic quantitative literature review to provide context to the historical experimental research of healthy older adults – compared to younger adults or unhealthy age matched cases – during exogenous heat strain, focusing on factors that influence thermoregulatory function (e.g. co-morbidities). We identified 4,455 articles, with 147 meeting eligibility criteria. Most studies were conducted in the US (39%), Canada (29%), or Japan (12%), with 71% of the 3,411 participants being male. About 71% of the studies compared younger and older adults, while 34% compared two groups of older adults with and without factors influencing thermoregulation. Key factors included age combined with another factor (23%), underlying biological mechanisms (18%), age independently (15%), influencing health conditions (15%), adaptation potential (12%), environmental conditions (9%), and therapeutic/pharmacological interventions (7%). Our results suggest that controlled experimental research should focus on the age-related changes in thermoregulation in the very old, females, those with overlooked chronic heat-sensitive health conditions (e.g. pulmonary, renal, mental disorders), the impact of multimorbidity, prolonged and cumulative effects of extreme heat, evidence-based policy of control measures (e.g. personal cooling strategies), pharmaceutical interactions, and interventions stimulating protective physiological adaptation. These controlled studies will inform the directions and use of limited resources in ecologically valid fieldwork studies. [ABSTRACT FROM AUTHOR]

Hijabs are predominantly worn in hot environments, but very rare studies on the thermo-physiological effects of wearing hijabs are found. We investigated the effects of wearing rayon and polyester hijabs on wearers' physiological and subjective responses in warm-humid and hot-dry environments. Eight females (25.0 ± 2.3 y in age, 157.7 ± 4.1 cm in height, and 50.8 ± 7.5 kg in weight) participated in three conditions (No hijab, rayon hijab, and polyester hijab condition) during exercise in two thermal environments: a warm-humid (30 °C and 70%RH) and a hot-dry environment (36 °C and 30%RH), which generated an identical wet-bulb globe temperature at 27 °C. The results showed that no differences in rectal temperature were found among the three clothing conditions or the two environments, whereas auditory canal temperature was higher in the hot-dry than in the warm-humid environment (P < 0.05) with no differences between the polyester and rayon hijab conditions. Mean skin temperature and neck temperature were higher for the polyester condition than for the rayon condition in the warm-humid environment (P < 0.05). Sweat rate was greater for the polyester hijab condition than for the no hijab condition in the warm-humid environment (P = 0.049). Heart rate was greater for the polyester hijab condition than for the other two conditions in the warm-humid environment (P < 0.05). Subjects felt more thermally uncomfortable when wearing the polyester hijab than the rayon hijab in the warm-humid environment. Greater thermal burden of the polyester hijab when compared to the rayon hijab was marked in the warm-humid environment, not in the hot-dry environment. [ABSTRACT FROM AUTHOR]

When the human body experiences heat stress beyond the normal range, it may affect health and work efficiency to a certain extent. This study aimed to investigate the effectiveness of cold stimulation on Dazhui point (GV14), bilateral Xinshu points (B15), bilateral Danshu points (B19), and bilateral Quchi points (LI11) in the body to relieve heat strain in a high-temperature environment. The experiment results showed that the skin temperature (Tskin), tympanic temperature (Tty), heart rate (HR), the physiological strain index based on heart rate (PSIHR), thermal sensation (TS), and thermal comfort (TC) of the participants with acupoints cold stimulation were better than those without acupoints cold stimulation (p < 0.05). Tskin decreased by an average of 0.04 ± 0.46Ԩ. Tty decreased by an average of 0.08 ± 0.21Ԩ. The study concluded that cold stimulation at acupoints could reduce the heat strain and improve the thermal comfort of the human body.

Heat strain is the body's physiological response to heat stress received by a person. This research is a type of quantitative research with a cross-sectional study approach. The sampling technique in this study was random sampling with a total sample of 80 respondents. They are collecting data using questionnaires and interviews. Methods of data analysis using univariate and bivariate analysis with Chi-square test at 95% confidence level (p=0.05). The results showed a significant relationship between drinking water consumption and the heat strain factor (p=0.001); there was no relationship between the length of work and the heat strain factor (p=0.455) for workers in the production division at PT. IKI (Persero) 2023. It can be concluded that there is a relationship between the variable consumption of drinking water and the heat strain factor, and there is no relationship between the length of work and the heat strain factor in workers in the production division of PT. IKI (Persero). Suggested: There is a need for special attention from the agency on the importance of controlling heat stress to reduce the risk of occupational diseases in production workers at PT. IKI (Persero).

Excessive solar radiation negatively affects cognitive performance. Occupational guidelines typically combine environmental components into one value, such as wet-bulb globe temperature (WBGT). Here, we evaluated cognitive performance in two similar 28.6 °C WBGT-effective (WBGTeff) that were designed differently; using high or low levels of solar radiation. Eight soldiers were exposed to a virtual-reality environment in a climate chamber set to high (900 Wm−2) or low solar radiation conditions (300 Wm−2). Soldiers walked 3 x 30 min at 5 kmh−1. Cognitive performance was evaluated using a virtual-reality scenario and a computerised test battery. There was no statistically significant effect of condition on the cognitive tasks (p > 0.05). Associations were found between mean body temperature (Tb) and visual detection (P ≤ 0.01). Differences in solar radiation with similar WBGTeff (28.6 °C) do not cause large systematic differences in cognitive performance. Certain aspects of cognitive performance (i.e. response inhibition) seem to be partly associated with Tb rather than solar radiation. Practitioner summary: Cognitive performance was evaluated in two similar WBGT conditions that were designed differently; using high or low levels of solar radiation. Differences in solar radiation with similar WBGT do not cause systematic differences in cognitive performance. Certain aspects of cognition were partly associated with mean body temperature rather than solar radiation. [ABSTRACT FROM AUTHOR]

Until now, only a few comprehensive studies have validated analytical heat stress indices in different conditions. The present study aims to investigate the validity of these indicators in predicting the physiological parameters of workers. This cross-sectional study was conducted with 194 male employees working in warm environments. First, demographic information was collected. After participants rested for 30 min, their heart rate and tympanic temperature were measured. The subjects then performed their routine tasks. At the end of 90 min, their heart rate and tympanic temperature were again measured. Additionally, their metabolism rate and clothing thermal insulation were estimated. Environmental parameters were also measured at 30-, 60-, and 90-min time points. Additional information required to compute the indices was recorded. Then, the values of each of the indices were computed. Finally, the validity of the indices was assessed under different conditions. The results indicated that the highest regression coefficients with tympanic temperature were assigned to modified physiologically equivalent temperature (mPET) (0.7515), predicted heat strain (PHS) (0.7201), and predicted mean vote (PMV) (0.7082), index, respectively. Also, the greatest regression coefficients with heart rate belonged to mPET (0.7773), PMV (0.7624), and PHS (0.6479) index, respectively. Based on the results, the highest diagnostic accuracies of receiver operating characteristic (ROC) curves for tympanic temperature were related to indices of mPET, PHS, and PMV with the area under the ROC curve (AUC) of 0.945, 0.931, and 0.930, respectively. Of the studied indices, it was observed that mPET, PHS, PMV, and PPD showed more validity compared to others. [ABSTRACT FROM AUTHOR]

The objective of our study was to assess the impact of heat stress on hydration and cognition among outdoor workers in hot environment. Area heat stress assessments were measured using Quest Temp WBGT monitor. Sweat rate for dehydration and reaction time for acute cognitive processing were recorded using standard procedures. Heat stress measurements ranged from 23.8 °C – 42 °C. More than 50 % of the workers had high sweat rate (>1.2 L/h) when exposed to high environmental temperatures. Positive correlation was obtained between WBGT, sweat rate and reaction time which indicates that hyperthermia has an impact on neural network processing. Heart rate and reaction time also increased with rise in WBGT and heavy physical activity. There was impairment of cognitive functions (reaction time) under heat stress conditions. Hence, reaction time can be used to assess the short-term impact of heat stress on neural modulation and will help to plan effective intervention strategies to reduce morbidity and mortality among workers. [ABSTRACT FROM AUTHOR]

The expressed goal of limiting workplace heat stress exposures to a core temperature (Tc) of 38°C traces back to a 1969 World Health Organization Technical Report (WHO Series 412). The actual goal was to limit exposures to the upper limit of the prescriptive zone (ULPZ). To explore the physiological strain at the ULPZ, progressive heat stress protocol data from Penn State University (PSU) and University of South Florida (USF) below and at the ULPZ were used to articulate the relation of Tc and heart rate (HR) to metabolic rate (MR) with consideration of acclimatization state, clothing, exposure condition (PreULPZ vs. ULPZ), and sex. Regression models demonstrated the association of MR and sex with Tc and HR. At the ULPZ, women had systematically higher values of Tc and HR than men at the same MR likely due to higher relative demands. There was no effect for acclimatization state and clothing. As expected for individuals, Tc was practically constant below the ULPZ and HR exhibited increasing values approaching the ULPZ. At 490 W, the high MR cited in the WHO document, the mean Tc for men was near the 38°C limit with systematically lower Tc at lower MRs. [ABSTRACT FROM AUTHOR]

Context and background Extreme heat is one of the challenges facing urban areas. Though this constitutes a global urban challenge especially large cities in the world, urban studies have barely paid attention to urban heat. Goal and Objective: This study sought to examine government and community responses and adaptation strategies to extreme heat, using a case of Dar es Salaam city in Tanzania. Methodology: Kigogo ward in the city of Dar es Salaam was selected as a case study area. Household questionnaire was the main method used for data collection. Through quantitative methods, a total of 100 households in Kigogo ward were surveyed. Collected data were analysed using Stata software. Results: The findings show that residents adapted to extreme heat drawing on their own knowledge and personal initiatives. Regardless of education level, income status and household size all male and female perceive heat strain. The study also revealed association between independent variables and adaptation strategies, for example results for level of education vis a vis some extreme heat mitigation strategies are as follows: frequent drinking of water (χ² (1) = 63.371 p-value = 0.000), planting of trees (χ² (1) = 2.559, p-value = 0.110) and watercooling strategy using ice (ꭓ2(1) = 5.099, p-value = 0.014). The study concluded that heat and its related impacts have not received due attention in urban policy and city's authorities despite noticeable impacts on residents. The research suggests the city authorities place emphasis on heat information, awareness creation and education to minimize its adverse effects on residents. [ABSTRACT FROM AUTHOR]

Extreme heat events directly impact worker health and cause additional cascading and transitional workplace impacts. However, current investigations on these impacts often rely on specific datasets (e.g., compensation claims, hospitalizations). Thus, to continue to work towards preventing and mitigating the occupational risks posed by extreme heat events, this study aimed to explore the occupational impacts of the 2021 Heat Dome in Canada using a qualitative content analysis method on a news-based dataset. A systematized review of news articles published before, during, and after the 2021 Heat Dome was conducted on academic (n = 8) and news (n = 5) databases, along with targeted grey literature. Two researchers qualitatively coded the articles in NVivo for occupational impacts or references mentioned within the articles. Overall, 52 different occupations were identified as being impacted by the 2021 Heat Dome. Impacts were diverse and ranged from work cancellations or delays to work modifications and reports of heat-related illnesses. The 2021 Heat Dome impacted the health and safety of many occupational groups and provided new insights into the expanding impacts that extreme heat events can have on the Canadian workforce. With climate projections showing a growing trend of more hot days and intense heat waves in Canada, addressing these concerns should be a critical priority. [ABSTRACT FROM AUTHOR]

Abstract The expressed goal of limiting workplace heat stress exposures to a core temperature (Tc) of 38°C traces back to a 1969 World Health Organization Technical Report (WHO Series 412). The actual goal was to limit exposures to the upper limit of the prescriptive zone (ULPZ). To explore the physiological strain at the ULPZ, progressive heat stress protocol data from Penn State University (PSU) and University of South Florida (USF) below and at the ULPZ were used to articulate the relation of Tc and heart rate (HR) to metabolic rate (MR) with consideration of acclimatization state, clothing, exposure condition (PreULPZ vs. ULPZ), and sex. Regression models demonstrated the association of MR and sex with Tc and HR. At the ULPZ, women had systematically higher values of Tc and HR than men at the same MR likely due to higher relative demands. There was no effect for acclimatization state and clothing. As expected for individuals, Tc was practically constant below the ULPZ and HR exhibited increasing values approaching the ULPZ. At 490 W, the high MR cited in the WHO document, the mean Tc for men was near the 38°C limit with systematically lower Tc at lower MRs.

The present observational study was conducted to uncover potential differences in the risk of experiencing high occupational heat strain during agriculture work between migrants and their native coworkers, as well as to elucidate the factors that may contribute to such differences. The study took place over the period from 2016 through 2019 and involved monitoring 124 experienced and acclimatized individuals from high-income (HICs), upper-middle-income (UMICs), as well as lower-middle- and low-income (LMICs) countries. Baseline self-reported data for age, body stature, and body mass were collected at the start of the study. Second-by-second video recordings throughout the work shifts were captured using a video camera and were used to estimate workers' clothing insulation, covered body surface area, and body posture, as well as to calculate their walking speed, the amount of time they spent on different activities (and their intensity) and unplanned breaks throughout their work shifts. All information derived from the video data was used to calculate the physiological heat strain experienced by the workers. The core temperature of migrant workers from LMICs (37.81 ± 0.38 °C) and UMICs (37.71 ± 0.35 °C) was estimated to be significantly higher compared to the core temperature of native workers from HICs (37.60 ± 0.29 °C) (p < 0.001). Moreover, migrant workers from LMICs faced a 52% and 80% higher risk for experiencing core body temperature above the safety threshold of 38 °C compared to migrant workers from UMICs and native workers from HICs, respectively. Our findings show that migrant workers originating from LMICs experience higher levels of occupational heat strain, as compared to migrant workers from UMICs and native workers from HICs, because they take fewer unplanned breaks during work, they work at a higher intensity, they wear more clothing, and they have a smaller body size. [ABSTRACT FROM AUTHOR]

Increasing heatwave frequency due to climate change threatens outdoor workers' health. We aimed to assess the on-site heat strain level of outdoor workers using wearable sensors and identify the factors for consideration in developing individual-based heat adaptation strategies. Seven road construction workers were recruited and asked to wear necklace-form temperature loggers and smartwatches monitoring heart rate (HR). The questionnaire was delivered daily to ask about their psychological comfort level during work. Workers were exposed to up to 5.4 °C higher temperature than the official air temperature, indicating that the national heatwave alarm does not reflect on-site heat conditions. Based on the measured HR data, heat strain levels were defined. When HR exceeded the level of "180-age," we assumed extreme heat strain occurred, which requires immediate cessation of work. When HR exceeded 40% of the individual heart rate reserve (the difference between the maximum and resting HR), we assumed high heat strain occurred, indicating a stressed condition. High heat strain occurred in all workers on 9 of the 13 monitored days, whereas the official heatwave alarms were issued only on four dates. Additionally, three workers experienced extreme heat strain on two dates. The main factor for workers experiencing extreme heat strain was age. Comparing the heat strain levels from HR with the survey results, we found that the older workers considered their condition comfortable even under extreme and high heat strain. Thus, an individual sensor-based early-warning system is needed to prevent heat strain not perceived by outdoor workers. The findings emphasize the need for a personalized adaptation strategy for heatwaves and will be a baseline for developing a new work manual that mainstreams climate change impacts. [ABSTRACT FROM AUTHOR]

Purpose: Klotho is a cytoprotective protein that increases during acute physiological stressors (e.g., exercise heat stress), although age-related declines in klotho may underlie cellular vulnerability to heat stress. The present study aimed to compare serum klotho in healthy older men and men with type 2 diabetes (T2D) or hypertension (HTN) during prolonged exercise in temperate or hot conditions. Methods: We evaluated serum klotho in 12 healthy older men (mean [SD]; 59 years [4]), 10 men with HTN (60 years [4]), and 9 men with T2D (60 years [5]) before and after 180 min of moderate-intensity (fixed metabolic rate of 200 W/m2; ~ 3.4 METs) exercise and 60 min of recovery in temperate (wet-bulb globe temperature (WBGT) 16 °C) and hot (WBGT 32 °C) environments. Core temperature (rectal), heart rate (HR), and heart rate reserve (HRR) were measured continuously while klotho was measured at the end of baseline, exercise, and recovery. Results: Total exercise duration was reduced during the hot condition in older men with HTN and T2D than healthy older men (both p ≤ 0.049), despite similar core temperatures, HR, and HRR. Klotho was higher than rest following exercise in the heat in healthy older men (+ 191 pg/mL [189]; p < 0.001) and responses were greater (p = 0.036) than men with HTN (+ 118 pg/mL [49]; p = 0.030), although klotho did not increase in men with T2D (+ 4 pg/mL [71]; p ≥ 0.638). Conclusion: Given klotho's role in cytoprotection, older men with HTN and especially T2D may be at increased cellular vulnerability to prolonged exercise or physically demanding exercise in the heat. [ABSTRACT FROM AUTHOR]

Background: With rising temperature extremes, older workers are becoming increasingly vulnerable to heat‐related injuries because of age‐ and disease‐associated decrements in thermoregulatory function. Endothelial monocyte‐activating polypeptide‐II (EMAP‐II) is a proinflammatory cytokine that has not yet been well‐characterized during heat stress, and which may mediate the inflammatory response to high levels of physiological strain. Methods: We evaluated serum EMAP‐II concentrations before and after 180 min of moderate‐intensity work (200 W/m2) in temperate (wet‐bulb globe temperature [WBGT] 16°C) and hot (WBGT 32°C) environments in heat‐unacclimatized, healthy young (n = 13; mean [SD]; 22 [3] years) and older men (n = 12; 59 [4] years), and unacclimatized older men with hypertension (HTN) (n = 10; 60 [4] years) or type 2 diabetes (T2D) (n = 9; 60 [5] years). Core temperature and heart rate were measured continuously. Results: In the hot environment, work tolerance time was lower in older men with HTN and T2D compared to healthy older men (both p < 0.049). While core temperature and heart rate reserve increased significantly (p < 0.001), they did not differ across groups. End‐exercise serum EMAP‐II concentrations were higher in young men relative to their older counterparts due to higher baseline levels (both p ≤ 0.02). Elevations in serum EMAP‐II concentrations were similar between healthy older men and older men with HTN, while serum EMAP‐II concentrations did not change in older men with T2D following prolonged work in the heat. Conclusion: Serum EMAP‐II concentrations increased following prolonged moderate‐intensity work in the heat and this response is influenced by age and the presence of HTN or T2D. [ABSTRACT FROM AUTHOR]

Research to date provides equivocal evidence regarding the influence of heat stress, heat strain, and more specifically, elevated exercise-induced core temperature on cognitive performance. This review sought to identify differences in how specific cognitive tasks were affected by increases in core body temperatures. Included papers (n = 31) measured cognitive performance and core temperature during exercise, while experiencing heightened thermal stress. Cognitive tasks were classified as cognitive inhibition, working memory, or cognitive flexibility tasks. Independently, core temperature changes were not sufficient predictors of cognitive performance. However, reaction time, memory recall, and Stroop tasks appeared to be most effective at identifying cognitive changes during heightened thermal strain. Alterations in performance were more likely to arise under increased thermal loads, which were typically associated with cumulative physiological stressors, such as elevated core temperatures, occurring alongside dehydration, and prolonged exercise durations. Future experimental designs should consider the relevance, or futility of assessing cognitive performance in activities that do not elicit a considerable degree of heat strain, or physiological load. [ABSTRACT FROM AUTHOR]

Heat stress is one of the most common complaints of health care employees who wear isolation gowns to protect themselves from biological agents, particularly during the warmer seasons. This study was conducted in a climatic chamber to determine the influence of airflow within isolated hospital gowns on physiological-perceptual heat strain indices. The experiment was conducted in three trials: regular clothes (CON), an impenetrable gown without air blowing (GO), and a gown with air blowing (GO + FAN) at temperature conditions of 27 °C and 25% relative humidity (RH). During the trial, physiological-perceptual response data were recorded for a half-hour on a treadmill at a speed of km/hr and a slope of 0% activity at 5-min intervals. The ASHRAE Likert scale was used to assess thermal comfort (TC), thermal sensation (TS), and skin wetness sensation (WS). As the results show, there was a significant difference in mean scores for TC and WS in both sexes when working in the CON, GO, and GO + FAN groups (P < 0.001). In women, the mean scores for TS, TC, and WS reduced considerably (P < 0.001) in the GO and GO + FAN in the amount of 10 and 12 CFM (20 m 3 /h), but in males, there was a statistically significant difference between mean scores (P < 0.001) in the GO + FAN at 12 CFM (20 m 3 /h) and 14 CFM (24 m 3 /h). Also, the greatest difference between the average heart rate, chest temperature, and temperature inside the clothes in women and men in the trials GO and GO + FAN was observed in the air flow 12 CFM and 14 CFM, respectively (P < 0.001). The usage of an air blower in isolated hospital clothes has been shown to influence physiological-perceptual parameters in men and women substantially. The existence of airflow in these gowns can improve safety, performance, and thermal comfort while also decreasing the risk of heat-related disorders. [ABSTRACT FROM AUTHOR]

Abstract Background Farmworkers are at risk of heat-related illness (HRI). We sought to: 1) evaluate the effectiveness of farmworker Spanish/English participatory heat education and a supervisor decision-support mobile application (HEAT intervention) on physiological heat strain; and 2) describe factors associated with HRI symptoms reporting. Methods We conducted a parallel, comparison group intervention study from May–September of 2019 in Central/Eastern Washington State, USA. We used convenience sampling to recruit adult outdoor farmworkers and allocated participating crews to intervention (n = 37 participants) and alternative-training comparison (n = 38 participants) groups. We measured heat strain monthly using heart rate and estimated core body temperature to compute the maximum work-shift physiological strain index (PSImax) and assessed self-reported HRI symptoms using a weekly survey. Multivariable linear mixed effects models were used to assess associations of the HEAT intervention with PSImax, and bivariate mixed models were used to describe factors associated with HRI symptoms reported (0, 1, 2+ symptoms), with random effects for workers. Results We observed larger decreases in PSImax in the intervention versus comparison group for higher work exertion levels (categorized as low, low/medium-low, and high effort), after adjustment for maximum work-shift ambient Heat Index (HImax), but this was not statistically significant (interaction − 0.91 for high versus low/medium-low effort, t = − 1.60, p = 0.11). We observed a higher PSImax with high versus low/medium-low effort (main effect 1.96, t = 3.81, p 3 min to get to the toilet at work. Conclusions Effort level should be addressed in heat management plans, for example through work/rest cycles, rotation, and pacing, in addition to education and other factors that influence heat stress. Both symptoms and indicators of physiological heat strain should be monitored, if possible, during periods of high heat stress to increase the sensitivity of early HRI detection and prevention. Structural barriers to HRI prevention must also be addressed. Trial registration ClinicalTrials.gov Registration Number: NCT04234802 , date first posted 21/01/2020.

As a cooling device for cooling the human body, the cooling garment has been used in many fields. This study was guided by the theory of traditional Chinese medicine, an acupoints-meridians cooling vest (AMCV) system was designed to cold and stimulate the acupoints and meridians of the human body. Three healthy male subjects were recruited to participate in the test, with AMCV or without AMCV (CON), in a high temperature environment (37 ±1, 46 ±3% RH) to simulate standing on duty for 50 minutes. The results showed that the skin temperature, Tskin, with AMCV was lower than that with CON (p < 0.05). The average Tskin with AMCV decreased by 0.45 more than that with CON (p < 0.05). The average tympanic temperature, Tty, with AMCV was lower than that with CON (p < 0.05). However, the average Tty with AMCV decreased by 0.05 more than that with CON (p < 0.05). The heart rate with AMCV was significantly lower than that with CON (p < 0.05). The average thermal sensation and thermal comfort with AMCV were better than those with CON in the corresponding period (p < 0.05). The results indicated that AMCV could improve thermal comfort and reduce the heat strain of the human body in a high temperature environment. [ABSTRACT FROM AUTHOR]

Purpose: To determine if the Physiological Strain Index (PSI), in original or modified form, can evaluate heat strain on a 0-10 scale, in trained and heat-acclimatized men undertaking a competitive half-marathon run in outdoor heat. Methods: Core (intestinal) temperature (TC) and heart rate (HR) were recorded continuously in 24 men (mean [SD] age = 26 [3] y, VO2peak = 59 [5] mL⋅kg⋅min-1). A total of 4 versions of the PSI were computed: original PSI with upper constraints of TC 39.5°C and HR 180 beats⋅min-1 (PSI39.5/180) and 3 modified versions of PSI with each having an age-predicted maximal HR constraint and graded TC constraints of 40.0°C (PSI40.0/PHRmax) 40.5°C (PSI40.5/PHRmax) and 41.0°C (PSI41.0/PHRmax). Results: In a warm (26.1-27.3°C) and humid (79-82%) environment, all runners finished the race asymptomatic in 107 (10) (91-137) min. Peak TC and HR were 39.7°C (0.5°C) (38.5-10.7°C) and 186 (6) (175-196) beats⋅min-1, respectively. In total, 63% exceeded TC 39.5°C, 71% exceeded HR 180 beats⋅min-1, and 50% exceeded both of the original PSI upper TC and HR constraints. The computed heat strain was significantly greater with PSI39.5/180 than all other methods (P <0.003). PSI >10 was observed in 63% of runners with PSI39.5/180, 25% for PSI40.0/PHRmax, 8% for PSI40.5/PHRmax, and 0% for PSI41.0/PHRmax. Conclusions: The PSI was able to quantify heat strain on a 0-10 scale in trained and heat-acclimatized men undertaking a half-marathon race in outdoor heat, but only when the upper TC and HR constraints were modified to 41.0°C and age-predicted maximal HR, respectively. [ABSTRACT FROM AUTHOR]

Objectives: To evaluate the efficacy of water‐cooled clothing that continuously cools restricted body areas to suppress body temperature increase as an anti‐heatstroke measure for workers in hot environments that exceed body temperature. Methods: Ten healthy men were placed in Room A (air temperature: 25°C, relative humidity: 50%) for 15 min. They were then transferred to Room B (air temperature: 40°C, relative humidity: 50%), where they rested for 10 min, then put on cooling clothing, and again rested for 15 min (the control group rested for 25 min). They then performed intense ergometer exercise for 40 min at 40% maximal oxygen consumption after which they rested for 10 min. The three trial conditions were CON (long‐sleeved summer work clothes), VEST (cooling vest), and P‐VEST (partial cooling vest). In VEST and P‐VEST, water‐cooled clothing continuously recirculated with 10°C water was used to cool the upper body. In P‐VEST, only the neck, axillae, and heart areas were in contact with the cooled clothing. The measured indices were the rectal, esophageal, and external auditory canal temperatures; heart rate; estimated sweat volume; and subjective evaluations. Results: Compared with the CON condition, the rectal, esophageal, and external auditory canal temperatures and the heart rate were significantly lower and the subjective indices were decreased in the VEST and P‐VEST conditions. Conclusions: Partial cooling showed a body cooling effect similar to that of whole upper body cooling. Partial body cooling promoted the heat dissipation, suggesting that partial cooling is efficient for maintaining body cooling in hot environments. [ABSTRACT FROM AUTHOR]

• Variability in heat response has been identified, attributed to differences in physical properties and body composition. • A categorization strategy for workers were developed based on physical attributes and body compositions. • Empirical work/rest schedules were formulated to accommodate physiological variations in workers' responses to heat. • These developed work/rest schedules ensure workers' safety while enhancing operational efficiency in construction projects. Responding to the urgent necessity for improved worker safety under rising global temperatures, this study proposes adaptive work/rest schedules tailored for varied physiological heat responses, a critical consideration in environments like construction. This study included 30 male participants in controlled chamber experiments to assess their physical attributes, body composition, and heat responses under two settings: 'Scenario I' at 30 °C with 40 % relative humidity, and 'Scenario II' at 37 °C with 70 % relative humidity. Cluster analysis was utilized, along with survival analysis targeting two primary events: 'Event I' , the rise of core body temperature to or above 38 °C during tasks, and 'Event II' , its normalization during recovery. Key findings include: (i) application of clustering techniques effectively differentiated the participants into two groups: 'Cluster I' , with below-average, and 'Cluster II' with above-average body profiles; (ii) empirical evidence from this study reveals marked differences in heat stress responses between these clusters; notably, individuals in 'Cluster II' faced a significantly higher risk of experiencing 'Event I' and demonstrated slower recovery in 'Event II' compared to 'Cluster I' ; (iii) this study proposed tailored adaptive work/rest schedules designed to provide a customized approach to managing heat stress, benefiting younger laborers; and (iv) compared to National Institute for Occupation Safety and Health guidelines, these schedules indicate the potential for extending work intervals and reducing rest periods, boosting operational efficiency without compromising worker safety. This paper underscores the importance of tailoring work/rest schedules to individual physiological responses to heat stress, providing essential insights for labor management in challenging conditions. [ABSTRACT FROM AUTHOR]

Thermal stress has a direct effect on various types of DNA damage, which depends on the stage of the cell cycle when the cell is exposed to different climate conditions. A literature review was conducted to systematically investigate and assess the overall effect of heat stress and DNA damage following heat exposure. In this study, electronic databases including PubMed, Scopus, and Web of Science were searched to find relevant literature on DNA damage in different ambient temperatures. Outcomes included (1) measurement of DNA damage in heat exposure, (2) three different quantification methods (comet assay, 8-hydroxy-2-deoxyguanosine (8-OHdG), and γ-H2AX), and (3) protocols used for moderate (31) and high temperatures (42). The evidence shows that long exposure and very high temperature can induce an increase in DNA damage through aggregate in natural proteins, ROS generation, cell death, and reproductive damage in hot-humid and hot-dry climate conditions. A substantial increase in DNA damage occurs following acute heat stress exposure, especially in tropical and subtropical climate conditions. The results of this systematic literature review showed a positive association between thermal stress exposure and inhibition of repair of DNA damage. [ABSTRACT FROM AUTHOR]

Background: Farmworkers are at risk of heat-related illness (HRI). We sought to: 1) evaluate the effectiveness of farmworker Spanish/English participatory heat education and a supervisor decision-support mobile application (HEAT intervention) on physiological heat strain; and 2) describe factors associated with HRI symptoms reporting.Methods: We conducted a parallel, comparison group intervention study from May-September of 2019 in Central/Eastern Washington State, USA. We used convenience sampling to recruit adult outdoor farmworkers and allocated participating crews to intervention (n = 37 participants) and alternative-training comparison (n = 38 participants) groups. We measured heat strain monthly using heart rate and estimated core body temperature to compute the maximum work-shift physiological strain index (PSImax) and assessed self-reported HRI symptoms using a weekly survey. Multivariable linear mixed effects models were used to assess associations of the HEAT intervention with PSImax, and bivariate mixed models were used to describe factors associated with HRI symptoms reported (0, 1, 2+ symptoms), with random effects for workers.Results: We observed larger decreases in PSImax in the intervention versus comparison group for higher work exertion levels (categorized as low, low/medium-low, and high effort), after adjustment for maximum work-shift ambient Heat Index (HImax), but this was not statistically significant (interaction - 0.91 for high versus low/medium-low effort, t = - 1.60, p = 0.11). We observed a higher PSImax with high versus low/medium-low effort (main effect 1.96, t = 3.81, p < 0.001) and a lower PSImax with older age (- 0.03, t = - 2.95, p = 0.004), after covariate adjustment. There was no clear relationship between PSImax and the number of HRI symptoms reported. Reporting more symptoms was associated with older age, higher HImax, 10+ years agricultural work, not being an H-2A guest worker, and walking > 3 min to get to the toilet at work.Conclusions: Effort level should be addressed in heat management plans, for example through work/rest cycles, rotation, and pacing, in addition to education and other factors that influence heat stress. Both symptoms and indicators of physiological heat strain should be monitored, if possible, during periods of high heat stress to increase the sensitivity of early HRI detection and prevention. Structural barriers to HRI prevention must also be addressed.Trial Registration: ClinicalTrials.gov Registration Number: NCT04234802 , date first posted 21/01/2020. [ABSTRACT FROM AUTHOR]

Government entities issue recommendations that aim to maintain core temperature below 38.0°C and prevent dehydration [>2% body mass loss] in unacclimated workers exposed to heat. Hydration recommendations suggest drinking 237 mL of a cool sport drink every 15–20 min. This is based on the premise that ad libitum drinking results in dehydration due to inadequate fluid replacement, but this has never been examined in the background of recommendation compliant work in the heat. Therefore, we tested the hypothesis that ad libitum drinking results in >2% body mass loss during heat stress recommendation compliant work. Ten subjects completed four trials consisting of 4 hours of exposure to wet bulb globe temperatures (WBGT) of 24.1 ± 0.3°C (A), 26.6 ± 0.2°C (B), 28.5 ± 0.2°C (C), 29.3 ± 0.6°C (D). Subjects walked on a treadmill and work-rest ratios were prescribed as a function of WBGT [work:rest per hour – A: 60:0, B: 45:15, C: 30:30, D: 15:45] and were provided 237 mL of a cool sport drink every 15 min to drink ad libitum. Mean core temperature was higher in Trial A (37.8 ± 0.4°C; p = 0.03) and Trial B (37.6 ± 0.3°C; p = 0.01) versus Trial D (37.3 ± 0.3°C) but did not differ between the other trials (p ≥ 0.20). Body mass loss (A: −0.9 ± 0.7%, B: −0.7 ± 0.5%, C: −0.3 ± 0.5%, D: −0.4 ± 0.6%) was greater in Trial A compared to Trial D (p = 0.04) and was different from 2% body mass loss in all trials (p ≤ 0.01). Ad libitum drinking during recommendation compliant work in the heat rarely resulted in dehydration. Registered Clinical Trial (NCT04767347) [ABSTRACT FROM AUTHOR]

In a series of three companion papers published in this Journal, we identify and validate the available thermal stress indicators (TSIs). In this second paper of the series, we identified the criteria to consider when adopting a TSI to protect individuals who work in the heat, and we weighed their relative importance using a Delphi exercise with 20 experts. Two Delphi iterations were adequate to reach consensus within the expert panel (Cronbach's α = 0.86) for a set of 17 criteria with varying weights that should be considered when adopting a TSI to protect individuals who work in the heat. These criteria considered physiological parameters such as core/skin/mean body temperature, heart rate, and hydration status, as well as practicality, cost effectiveness, and health guidance issues. The 17 criteria were distributed across three occupational health-and-safety pillars: (i) contribution to improving occupational health (55% of total importance), (ii) mitigation of worker physiological strain (35.5% of total importance), and (iii) cost-effectiveness (9.5% of total importance). Three criteria [(i) relationship of a TSI with core temperature, (ii) having categories indicating the level of heat stress experienced by workers, and (iii) using its heat stress categories to provide recommendations for occupational safety and health] were considered significantly more important when selecting a TSI for protecting individuals who work in the heat, accumulating 37.2 percentage points. These 17 criteria allow the validation and comparison of TSIs that presently exist as well as those that may be developed in the coming years. [ABSTRACT FROM AUTHOR]

In a series of three companion papers published in this Journal, we identify and validate the available thermal stress indicators (TSIs). In this third paper, we conducted field experiments across nine countries to evaluate the efficacy of 61 meteorology-based TSIs for assessing the physiological strain experienced by individuals working in the heat. We monitored 372 experi-enced and acclimatized workers during 893 full work shifts. We continuously assessed core body temperature, mean skin temperature, and heart rate data together with pre/post urine specific gravity and color. The TSIs were evaluated against 17 published criteria covering physiological parameters, practicality, cost effectiveness, and health guidance issues. Simple meteorological parameters explained only a fraction of the variance in physiological heat strain (R2 = 0.016 to 0.427; p < 0.001), reflecting the importance of adopting more sophisticated TSIs. Nearly all TSIs correlated with mean skin temperature (98%), mean body temperature (97%), and heart rate (92%), while 66% of TSIs correlated with the magnitude of dehydration and 59% correlated with core body temperature (r = 0.031 to 0.602; p < 0.05). When evaluated against the 17 published criteria, the TSIs scored from 4.7 to 55.4% (max score = 100%). The indoor (55.4%) and outdoor (55.1%) Wet-Bulb Globe Temperature and the Universal Thermal Climate Index (51.7%) scored higher compared to other TSIs (4.7 to 42.0%). Therefore, these three TSIs have the highest potential to assess the physiological strain experienced by individuals working in the heat. [ABSTRACT FROM AUTHOR]

In a series of three companion papers published in this Journal, we identify and validate the available thermal stress indicators (TSIs). In this first paper of the series, we conducted a systematic review (registration: INPLASY202090088) to identify all TSIs and provide reliable information regarding their use (funded by EU Horizon 2020; HEAT-SHIELD). Eight databases (PubMed, Agricultural and Environmental Science Collection, Web of Science, Scopus, Embase, Russian Science Citation Index, MEDLINE, and Google Scholar) were searched from database inception to 15 April 2020. No restrictions on language or study design were applied. Of the 879 publications identified, 232 records were considered for further analysis. This search identified 340 instruments and indicators developed between 200 BC and 2019 AD. Of these, 153 are nomograms, instruments, and/or require detailed non-meteorological information, while 187 can be mathematically calculated utilizing only meteorological data. Of these meteorology-based TSIs, 127 were developed for people who are physically active, and 61 of those are eligible for use in occupational settings. Information regarding the equation, operating range, interpretation categories, required input data, as well as a free software to calculate all 187 meteorology-based TSIs is provided. The information presented in this systematic review should be adopted by those interested in performing on-site monitoring and/or big data analytics for climate services to ensure appropriate use of the meteorology-based TSIs. Studies two and three in this series of companion papers present guidance on the application and validation of these TSIs, to guide end users of these indicators for more effective use. [ABSTRACT FROM AUTHOR]

Introduction: Due to rising temperature extremes, workplaces are seeking new solutions, such as using personal cooling garments (PCG) to mitigate and manage workplace heat exposure. This systematic review sought to assess the physiological and perceptual effects of PCGs on workers in standard work clothing performing moderate-to-heavy intensity tasks in hot environments., Methods: A peer-reviewed search strategy was conducted in MEDLINE, Embase, CINAHL, Scopus, Global Health, and Business Source Complete with no language or time limits. A meta-analysis using a realist evaluation framework was then performed to evaluate the effectiveness of the PCGs., Results: Thirty-three studies with 764 participants (98% male; average 21 ± 34 participants per study), conducted primarily in a laboratory setting (76%) were included. The studies were 193 ± 190 min in duration and consisted of a moderate-to-heavy work effort of 3.3 ± 1.0 METs in hot ambient conditions (temperature: 35.9 ± 3.3°C, 51.4 ± 12.1% relative humidity, wet bulb globe temperature [WBGT] 31.2 ± 2.6°C). The PCGs (n = 67) facilitated heat exchange through conduction (n = 39), evaporation (n = 4), convection (n = 2), radiation (n = 2), or hybrid combinations (n = 20). Conductive and hybrid PCGs offered the greatest thermoregulatory benefit, whereby core temperature (T c ) and heart rate (HR) reductions were consistently observed (Conductive: T c : -0.3°C, HR: -12 bpm; Hybrid: T c: :-0.2°C, HR: -10 bpm), while PCGs directed at enhancing evaporative and radiative heat exchange had no or minimal effect on the physiological outcomes assessed (i.e., T C  < 0.1°C, HR: <0.7 bpm)., Conclusion: While the PCGs had a positive overall effect, conductive options offered the most consistent benefit to workers. WBGT, clothing insulation, and duration of wear significantly affected some physiological and perceptual outcomes., (© 2024 The Author(s). American Journal of Industrial Medicine published by Wiley Periodicals LLC.)

Firefighters risk heat strain during occupational tasks when exposed to extremely hot environmental conditions and performing high-intensity work. Relevant training scenarios are therefore essential. This study investigated the effect of a single simulated smoke dive and the following recovery phase on physiological and perceptual responses. Nineteen professional male firefighters (43 ± 8 yr) performed a 2-min stair walk and a15-min simulated smoke dive in a two-floor heat chamber (110°C to 272°C) (HEAT), followed by a 5-min stair walk outside the heat chamber. Heart rate (HR), gastrointestinal temperature (T gi ) and skin temperatures were registered continuously during the test. The T gi increased significantly from the start (37.5 ± 0.3°C) to the end of HEAT (38.4 ± 0.4°C) and further increased after the heat exposure (39.6 ± 0.5°C). The HR also increased significantly from the start (92 ± 14 bpm) to the end of HEAT (185 ± 13 bpm) and increased after the heat exposure to a maximum of 190 ± 13 bpm. The simulated smoke dive induced high physiological strain on the firefighters, and the increase in T gi and HR after the hot exposure must be considered during live fire events when repeated smoke dives are required.

Extreme heat events directly impact worker health and cause additional cascading and transitional workplace impacts. However, current investigations on these impacts often rely on specific datasets (e.g., compensation claims, hospitalizations). Thus, to continue to work towards preventing and mitigating the occupational risks posed by extreme heat events, this study aimed to explore the occupational impacts of the 2021 Heat Dome in Canada using a qualitative content analysis method on a news-based dataset. A systematized review of news articles published before, during, and after the 2021 Heat Dome was conducted on academic (n = 8) and news (n = 5) databases, along with targeted grey literature. Two researchers qualitatively coded the articles in NVivo for occupational impacts or references mentioned within the articles. Overall, 52 different occupations were identified as being impacted by the 2021 Heat Dome. Impacts were diverse and ranged from work cancellations or delays to work modifications and reports of heat-related illnesses. The 2021 Heat Dome impacted the health and safety of many occupational groups and provided new insights into the expanding impacts that extreme heat events can have on the Canadian workforce. With climate projections showing a growing trend of more hot days and intense heat waves in Canada, addressing these concerns should be a critical priority.

Recent studies have characterized individually experienced temperatures or individually experienced heat indices, including new exposure metrics that capture dimensions of exposure intensity, frequency, and duration. Yet, few studies have examined the personal thermal exposure in underrepresented groups, like outdoor workers, and even fewer have assessed corresponding changes in physiologic heat strain. The objective of this paper is to examine a cohort of occupationally exposed grounds and public safety workers (n = 25) to characterize their heat exposure and resulting heat strain. In addition, a secondary aim of this work is to compare individually heat index exposure (IHIE) across exposure metrics, fixed-site in situ weather stations, and raster-derived urban heat island (UHI) measurements in Charleston, SC, a humid coastal climate in the Southeastern USA. A Bland–Altman (BA) analysis was used to assess the level of agreement between the personal IHIE measurements and weather-station heat index (HI) and Urban Heat Island (UHI) measurements. Linear mixed-effect models were used to determine the association between individual risk factors and in situ weather station measurements significantly associated with IHIE measurements. Multivariable stepwise Cox proportional hazard modeling was used to identify the individual and workplace factors associated with time to heat strain in workers. We also examined the non-linear association between heat strain and exposure metrics using generalized additive models. We found significant heterogeneity in IHIE measurements across participants. We observed that time to heat strain was positively associated with a higher IHIE, older age, being male, and among Caucasian workers. Important nonlinear associations between heat strain occurrence and the intensity, frequency, and duration of personal heat metrics were observed. Lastly, our analysis found that IHIE measures were significantly similar for weather station HI, although differences were more pronounced for temperature and relative humidity measurements. Conversely, our IHIE findings were much lower than raster-derived UHI measurements. Real-time monitoring can offer important insights about unfolding temperature-health trends and emerging behaviors during thermal extreme events, which have significant potential to provide situational awareness. [ABSTRACT FROM AUTHOR]