Climate change and heat stress resilient outdoor workers: findings from systematic literature review.

PURPOSE: Global warming has led to an increase in the number and intensity of extreme heat events, posing a significant threat to the health and safety of workers, especially those working outdoors, as they often have limited access to cooling strategies. The present systematic literature review (a) summarizes the current knowledge on the impacts of climate change on outdoor workers, (b) provides historical background on this issue, (c) explores factors that reduce and increase thermal stress resilience, (d) discusses the heat mitigation strategies, and (e) provides an overview of existing policy and legal frameworks on occupational heat exposure among outdoor workers. MATERIALS AND METHODS: In this systematic review, we searched scientific databases including Scopus (N = 855), Web of Science (N = 828), and PubMed (N = 202). Additionally, we identified relevant studies on climate change and heat-stress control measures through Google Scholar (N = 116) using specific search terms. In total, we monitored 2001 articles pertaining to worker populations (men = 2921; women = 627) in various outdoor climate conditions across 14 countries. After full-text assessment, 55 studies were selected for inclusion, and finally, 29 eligible papers were included for data extraction. RESULTS: Failure to implement effective control strategies for outdoor workers will result in decreased resilience to thermal stress. The findings underscore a lack of awareness regarding certain adaptation strategies and interventions aimed at preventing and enhancing resilience to the impact of climate change on heat stress prevalence among workers in outdoor tropical and subtropical environments. However, attractive alternative solutions from the aspects of economic and ecological sustainability in the overall assessment of heat stress resilience can be referred to acclimatization, shading, optimized clothing properties and planned breaks. CONCLUSION: The integration of climate change adaptation strategies into occupational health programs can enhance occupational heat resilience among outdoor workers. Conducting cost-benefit evaluations of health and safety measures for thermal stress adaptation strategies among outdoor workers is crucial for professionals and policymakers in low- and middle-income tropical and subtropical countries. In this respect, complementary measures targeting hydration, work-rest regimes, ventilated garments, self-pacing, and mechanization can be adopted to protect outdoor workers. Risk management strategies, adaptive measures, heat risk awareness, practical interventions, training programs, and protective policies should be implemented in hot-dry and hot-humid climates to boost the tolerance and resilience of outdoor workers.

Effect of air blowing inside isolated hospital clothing on perceptual and physiological heat strain in laboratory conditions.

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 [Formula: see text]/h), but in males, there was a statistically significant difference between mean scores (P < 0.001) in the GO + FAN at 12 CFM (20 [Formula: see text]/h) and 14 CFM (24 [Formula: see text]/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.

Effect of heat stress on DNA damage: a systematic literature review.

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.

Climate Change and Occupational Heat Strain Among Women Workers: A Systematic Review.

Climate change increases heat stress exposure and occupational heat strain in tropical and subtropical regions with generally hot-humid climate conditions. The present systematic review was conducted to assess the effect of climate change on occupational heat strain among women workers. In this study, three main databases (PubMed, Scopus, and Web of Science) were searched to find relevant literature on climate change and its effects using subject headings and appropriate MeSh terms. This article has been written according to the PRISMA checklist. A total of 6,176 studies were identified for screening and 13 studies were eligible for data extraction. Scientific evidence reveals that there is an imprecise but positive relationship between climate change and occupational heat strain regarding women workers. Some complications associated with occupational heat strain among women workers include fatigue, discomfort, dehydration, reduced brain function, and loss of concentration. Climate change can lead to an increase in the occurrence of heat-related illnesses and the levels of injury risk. In addition, its adverse health effects on women workers are mentioned. This systematic study identifies key priorities for action to better characterize and understand how occupational heat strain among women workers may be associated with climate change events. Strong evidence indicates that climate change will continue to cause occupational heat strain among women workers. It is essential to implement preventive measures considering multidisciplinary strategies to reduce the adverse effects of climate change on women workers health in hot weather settings. This can limit the health risks and negative effects of climate change.

The effect of cooling vests on physiological and perceptual responses: a systematic review.

Humans in hot environments are exposed to health risks and thermal discomfort which seriously affect their physical, physiological and mental workload. This study aimed to assess the effects of using cooling vests (CVs) on physiological and perceptual responses in the workplace. Three main databases were searched using subject headings and appropriate Mesh terms. The article has been written according to the preferred reporting items for systematic reviews checklist. A total of 23,837 studies were identified for screening and 63 studies were eligible for data extraction. A statistically significant difference was observed in body temperature among hybrid cooling garments (HBCGs), phase-change materials (PCMs) and air-cooled garments (ACGs) at 31.56-37 °C (60% relative humidity), evaporative cooling garments at 25.8-28.1 °C and liquid cooling garments at 35 °C (49% relative humidity) compared to without CVs (p < 0.001). HBCGs (PCMs and ACGs) are effective means in hot, moderate, humid or dry environments.

Thermal stress and TiO2 nanoparticle-induced oxidative DNA damage and apoptosis in mouse hippocampus.

Titanium dioxide (nano-TiO2) is used abundantly in various industrial products and novel medical therapies. In addition, the impact of climate change on the health and safety will undoubtedly increase in the future. However, the effects of exposure to these nanoparticles and heat stress on hippocampal DNA damage and apoptosis remain unclear. This study was conducted to evaluate the DNA damage and apoptosis in the hippocampal tissue and the physiological responses in mice induced by intraperitoneal (i.p.) administration of TiO2 nanoparticles (NPs) and heat stress for 14 consecutive days. The results showed that heat stress and TiO2-NPs were induced in the mouse hippocampus that led to hippocampal reactive oxygen species generation, oxidative damage of DNA, and apoptosis in a partly dose-dependent manner, especially at very hot temperature. High doses of nanosized TiO2 and severe heat stress significantly damaged the function of the hippocampus, as shown in the comet assay and apoptosis tests. The results of this study may provide data for appropriate measures to control and assess the risk of nano-TiO2 and thermal stress hazards to human health, especially workers. Safety guidelines and policies should be considered when handling nanomaterials in a hot environment.

Relationship of Environmental, Physiological, and Perceptual Heat Stress Indices in Iranian Men.

BACKGROUND: Heat stress is a known occupational hazard, which cause reduced exercise capacity. The purpose of this study was to evaluate the relationship among environmental, physiological, and perceptual heat stress indices in Iranian men. METHODS: This analytical study was carried out on 24 healthy men (age 23.34 ± 1.64 years) with normal body weight (body mass indices 21-25 kg/m(2)) in low workload for 120 min under hot climates (22-32°C, 40% relative humidity). Physiological strain index (PSI), wet-bulb globe temperature (WBGT), oral temperature, heart rate (HR), and heat strain score index (HSSI) questionnaires were simultaneous measurements taken at any 5 min during the exposure and resting state the initial measurements. RESULTS: The results showed that the range of WBGT index was 20.47-31.40°C. Significant correlation were found among WBGT and HSSI (r = 0.995), PSI (r = 0.990), oral temperature (r = 0.991), and HR (r = 0.972) indices. Also, significant correlation were found among HSSI and oral temperature (r = 0.983), HR (r = 0.978), and PSI (r = 0.987). CONCLUSIONS: The results have shown that simultaneous with the increase in valid indices of heat stress such as WBGT and PSI indices, the amount of HSSI has also increased with high power. Therefore, when there is no access to a reliable heat stress method such as WBGT, or PSI indices, HSSI, an observative and subjective heat strain method, can be used as a simple, fast in least 5 min, and inexpensive for evaluating the heat strain in Iranian men.

Validation of a questionnaire for heat strain evaluation in women workers.

INTRODUCTION: Physiological, anthropometrical and thermal perceptual are the most important factors affecting thermoregulation of men and women in workplaces. The purpose of this study was determining the validity of a questionnaire method for assessing women's heat strain in workplaces. METHODS: This cross-sectional study was carried out on 96 healthy women. Data were continuously collected over a period of 3 months (July-September) in 2012. Mean ± (SD) of age was found to be 31.5 ± 7.48 years, of height 1.61 ± 0.05 m, of weight 61.55 ± 10.35 kg, and of body mass index 23.52 ± 3.75 kg/m(2) in different workplaces. Heart rate and oral temperature were measured by heart rate monitoring and a medical digital thermometer, respectively. Subjects completed a draft questionnaire about the effective factors in the onset of heat strain. After collecting the questionnaires, the data were analyzed by applying Cronbach'sa calculation, factor analysis method, Pearson correlation and receiver operator characteristic curves using the SPSS 18 software. RESULTS: The value for Cronbach's α was found to be 0.68. The factor analysis method on items of draft questionnaire extracted three subscale (16 variables) which they explained 63.6% of the variance. According to the results of receiver operator characteristic curve analysis, the cut-off questionnaire score for separating people with heat strain from people with no heat strain was obtained to be 17. CONCLUSIONS: The results of this research indicated that this quantitative questionnaire has an acceptable reliability and validity, and a cut-off point. Therefore it could be used in the preliminary screening of heat strain in women in warm workplaces, when other heat stress evaluation methods are not available.