Increasing Heat Exposure Research Articles

Effect of stepwise cooking on the water-retention capacity and protein denaturation degree of chicken breast

This study investigated the impact of different center temperatures (60 °C, 65 °C, 70 °C) combined with low temperature long time cooking (cooking at 60 °C for 30 min or 60 min) on the water-retention capacity of chicken breasts. The effects of different heat treatment methods on microstructure, texture parameters, water content, cooking loss, color, pH value, protein denaturation degree and secondary structure content of chicken breast were analyzed. The results revealed that both center temperature and low temperature long times cooking (LTLT cooking) time significantly influenced the water-retention capacity of chicken breasts (P < 0.05). With increasing heat exposure levels, there was a corresponding rise in pH value as well as protein solubility and hydrophobicity in meat. This led to increased alignment of myofibrils along with gradual structural disruption and connective tissue efflux resulting in significant increases in meat hardness, chewiness and cooking loss (P < 0.05). However, when the center temperature reached 70 °C with an LTLT cooking time of 60 min, the muscle fiber structure is almost completely destroyed, causing the connective tissue between the muscle bundles or fibers to refill, resulting in a random coil content increase of about 2%, increased the water content by around 12% and decreased hardness by about 31%. These findings demonstrate that the group subjected to a combination treatment involving a center temperature of 70 °C and an LTLT cooking time of 60 min was effective in enhancing the water content while reducing the hardness of meat.

Impacts of heat exposure in utero on long-term health and social outcomes: a systematic review

BackgroundClimate change, particularly global warming, is amongst the greatest threats to human health. While short-term effects of heat exposure in pregnancy, such as preterm birth, are well documented, long-term effects have received less attention. This review aims to systematically assess evidence on the long-term impacts on the foetus of heat exposure in utero.MethodsA search was conducted in August 2019 and updated in April 2023 in MEDLINE(PubMed). We included studies on the relationship of environmental heat exposure during pregnancy and any long-term outcomes. Risk of bias was assessed using tools developed by the Joanna-Briggs Institute, and the evidence was appraised using the GRADE approach. Synthesis without Meta-Analysis (SWiM) guidelines were used.ResultsEighteen thousand six hundred twenty one records were screened, with 29 studies included across six outcome groups. Studies were mostly conducted in high-income countries (n = 16/25), in cooler climates. All studies were observational, with 17 cohort, 5 case-control and 8 cross-sectional studies. The timeline of the data is from 1913 to 2019, and individuals ranged in age from neonates to adults, and the elderly. Increasing heat exposure during pregnancy was associated with decreased earnings and lower educational attainment (n = 4/6), as well as worsened cardiovascular (n = 3/6), respiratory (n = 3/3), psychiatric (n = 7/12) and anthropometric (n = 2/2) outcomes, possibly culminating in increased overall mortality (n = 2/3). The effect on female infants was greater than on males in 8 of 9 studies differentiating by sex. The quality of evidence was low in respiratory and longevity outcome groups to very low in all others.ConclusionsIncreasing heat exposure was associated with a multitude of detrimental outcomes across diverse body systems. The biological pathways involved are yet to be elucidated, but could include epigenetic and developmental perturbations, through interactions with the placenta and inflammation. This highlights the need for further research into the long-term effects of heat exposure, biological pathways, and possible adaptation strategies in studies, particularly in neglected regions. Heat exposure in-utero has the potential to compound existing health and social inequalities. Poor study design of the included studies constrains the conclusions of this review, with heterogenous exposure measures and outcomes rendering comparisons across contexts/studies difficult.Trial RegistrationPROSPERO CRD 42019140136.

RISK-ORIENTED APPROACH TO THE ASSESSMENT OF WORKING CONDITIONS OF WORKERS WITH INCREASED THERMAL EXPOSURE

Problem statement. The issue of studying the working conditions of workers with increased heat exposure is considered. Diseases provoked by harmful working conditions have a rather long incubation period, so their manifestation is not always easy to recognize and there are difficulties in establishing the root cause of occupational disease. The purpose of the article. Development and implementation of risk assessment methodology based on the joint action of harmful and hazardous industrial factors and regularities of their intensity decrease with distance from the source. Methodology. The impact of occupational and heterogeneous industrial factors on the employee's health, taking into account the time of action and the impact of their joint action in quantitative form, can be fairly objectively assessed on the basis of the Weber-Fechner law through the calculation of the integral index of potential risk. Structural analysis was used to determine the structure and causes of occupational diseases. Correlation analysis was carried out to find out the nature of relationships between the levels of influence of factors of the industrial environment to assess the conditions and nature of labor at the workplaces of workers, at whose workplaces the increased thermal stress was installed. Probabilistic-statistical methods were used for data processing - to determine the algorithm of transformation of environmental parameters into an indicator of occupational risk for workers with harmful working conditions. Development of a model for determining the zones of transformation of occupational risk through mutual influence on the industrial risk of the processing of research results needed the application of formalization methods. A software system for the formation of aggregated for multivariate analysis of information was used, which made it possible to build a three-dimensional model of changes in the values of the indicator of occupational risk in the space between the workplaces of employees located in the welding department. Scientific novelty. The applied risk-oriented approach using the methods of occupational and industrial risk assessment for electric welders' workplaces allows to take into account the harm to the worker's organism from the factors of the industrial environment. The established regularities allow to determine the zones of transformation of occupational risk through mutual influence into production risk, which is the justification of measures to reduce injuries and occupational diseases. Practical value. On the example of labor conditions at the workplaces of electric welders the methodology of risk assessment is developed and tested taking into account the joint action of harmful and hazardous industrial factors and regularities of their intensity decrease with distance from the source. The given risk-oriented approach allows to fulfill all the requirements and recommendations set forth in ISO 45001: its application to the working conditions of workers of hot professions (welders) allows to carry out a quantitative assessment of occupational and industrial risk at their workplaces, in particular for preparation for certification under ISO 45001. Conclusions. An effective tool for theoretical analysis of pollution zones formed during an extreme situation at gas stations has been created. The results of computational experiments are presented. The methodology of risk assessment based on the fundamental Weber-Fechner law for objective assessment of the impact of occupational and heterogeneous industrial factors on the employee's health in quantitative form through the calculation of the integral index (potential risk), which will allow to assess the working conditions at workplaces and objectively determine the class of working conditions, has been developed and implemented.

Asymmetrical Flow Field Flow Fractionation for Molar Mass Characterization of Polyethylene Oxide in Abuse-Deterrent Formulations

High molar mass polyethylene oxide (HM-PEO) is commonly used to enhance the mechanical strength of solid oral opioid drug products to deter abuse. Because the properties of PEO depend on molar mass distribution, accurately determining the molar mass distribution is a necessary part of understanding PEO's role in abuse-deterrent formulations (ADF). In this study, an asymmetrical flow field-flow fractionation (AF4) analytical procedure was developed to characterize PEO polymers with nominal molar masses of 1, 4 or 7 MDa as well as those from in-house prepared placebo ADF. The placebo ADF were manufactured using direct compress or hot-melt-extrusion methods, and subjected to physical manipulation, such as heating and grinding before measurement by AF4 were performed. The molar mass distribution characterized by AF4 revealed that PEO was sensitive to thermal stress, exhibiting decreased molar mass with increased heat exposure. The optimized AF4 method was deemed suitable for characterizing HM-PEO, offering adequate dynamic separation range for PEO with molar mass from 100 kDa to approximately 10 MDa.

Quantifying urban heat exposure at fine scale - modeling outdoor and indoor temperatures using citizen science and VHR remote sensing

Global warming and advancing urbanization lead to an increased heat exposure for city dwellers. Especially during summertime heatwaves, extreme daytime as well as high nighttime temperatures expose vulnerable people to potentially deadly heat risk. This applies specifically to indoor air temperatures, since people spend a lot of their time indoors. Against this background, this study relates outdoor and indoor air temperature measurements to area-wide geospatial data regarding summertime urban heat in the city of Augsburg, Germany. Air temperature data is collected from formalized as well as citizen science measurements, while remote sensing data with very-high spatial resolution (VHR) is utilized for assessment of their drivers and influencing factors. A land use regression approach is developed for city-wide modeling of outdoor and indoor air temperatures at the level of individual residential buildings. Daytime outdoor temperatures could be largely explained by vegetation parameters and imperviousness, whereas nighttime temperatures were more related to the building stock and radiation properties. For indoor temperatures, building density as well as building height and volume are additionally relevant. Outdoor air temperatures could be modeled with higher accuracies (mean absolute error (MAE) < 0.5 °C) compared to indoor temperatures (MAE < 1.5 °C), whereas outdoor and indoor modeling results are consistent with well-known patterns across different local climate zones (LCZ).

Climate Change, Firm Performance, and Investor Surprises

We link records of firm performance, equity analyst forecast errors, and stock returns around companies’ earnings announcements to firm-specific measures of heat exposure for more than 17,000 firms in 93 countries from 1995 to 2019. We find that increased exposure to extremely high temperatures reduces firms’ revenues and operating income. A one-standard-deviation increase in the number of hot days decreases revenues (operating income) by 0.6% (1.8%) of the average quarterly revenue (operating income). Moreover, we provide evidence that increased heat exposure impacts negatively on firm financial performance relative to analyst predictions and on earnings announcement returns. These findings indicate that capital market participants do not fully anticipate the economic consequences of heat as a first order physical climate risk. This paper was accepted by Colin Mayer, Special Section of Management Science on Business and Climate Change. Funding: N. Pankratz gratefully acknowledges financial support from the French Social Investment Forum and the Principles for Responsible Investment [PhD Research Grant 2017]. Supplemental Material: Data are available at https://doi.org/10.1287/mnsc.2023.4685 .

Extreme Heat Impacts on the Viability of Alternative Transportation for Reducing Ozone Pollution: A Case Study from Maricopa County, Arizona

Abstract One commonly proposed strategy for reducing urban air pollution is transitioning from single-occupancy vehicle (SOV) travel to alternative transportation (AT) modes, such as walking, biking, and using public transportation. While many studies have addressed the benefits of switching from SOV to AT, fewer studies have examined the potential for negative outcomes due to increased exposure to heat when using AT modes. This work uses Maricopa County, Arizona, home to the metropolitan Phoenix area, as a test case to examine the potential impacts of heat on commuters who utilize AT. First, regions of the county with the most candidates for switching from SOV to AT were identified and used to develop an AT candidate index. This index was based on both the current rates of AT use and the number of SOV commuters with the shortest commuting times in the dataset (&lt;10 min). Next, typical weather conditions during warnings for high ozone (O3) pollution were examined. From 2017 to 2020, over one-quarter of all days with an O3 warning also were subject to an excessive heat warning. Last, land surface temperature data were used to determine the potential for increased heat exposure during AT commuting at both the ZIP code and AT infrastructure (public transit stops and bikeways) scales. Although this work focuses on Maricopa County, the issues presented here are increasingly relevant for cities across the world that are subject to poor air quality, hotter temperatures, and heat waves.

High Environmental Temperature: Insights into Behavioural, Neurodevelopmental and Gut Microbiome Changes Following Gestational Exposure in Rats

Adverse effects of changing climate have been associated with increase average global temperature resulting in environmental changes. We set out to investigate effects of environmental stress due to increased heat exposure on developmental milestones, behaviour, gut microbiota and neuroarchitecture in rat pups.Pregnant Wistar rats were held in standard temperature (ST) (26 ± 2 °C; control) or high temperature (HT) (40 ± 2 °C) housing. After parturition, a cohort of the HT group and their pups were moved to the control/ST housing (gestational-only-exposed pup [GE]) while the other subset remained in the HT housing (gestational and postnatal exposed pups [GE + PE]). At different time points, we examined neurodevelopmental milestones and behaviour in the pups. Following sacrifice changes in gut microbiota, neuroarchitecture, cytokine levels (TNF-α, IL-4, IL-10), SOD, MDA, expression of MBP, NeUN and GFAP were determined.We observed impaired positioning and placing of paws, prolonged righting reflex, delayed ear opening and significant decreased body weight gain in HT pups when compared with control. We identified Firmicutes and Proteobacteria and noted a significant difference in Firmicutes count between GE and GE + PE pups at P15. Furthermore, TNF-α, IL-4, IL-10 and MDA levels were increased in GE and GE + PE pups. There was also a reduction in MBP expression in the HT pups.Taken together, our results revealed a delay in neurodevelopmental milestones in pups exposed to high HT during gestation and post natal life. Pups whose dam were exposed to high HT during gestation also showed some set back but improved over the course of testing.

Thermal stress affects bioturbators' burrowing behavior: A mesocosm experiment on common cockles (Cerastoderma edule)

The intensity of marine heatwaves is increasing due to climate change. Heatwaves may affect macroinvertebrates' bioturbating behavior in intertidal areas, thereby altering the deposition-erosion balance at tidal flats. Moreover, small-scale topographic features on tidal flats can create tidal pools during the low tide, thus changing the heat capacity of tidal flats. These pools could then potentially operate as refuge environments during marine heatwaves. We studied behavior responses to heat waves using the well-known bioturbating cockle Cerastoderma edule as a model species. Different temperature regimes (i.e., fluctuating between 20 and 40 °C) and micro-topographies (i.e., presence vs. absence of tidal water pools) were mimicked in a mesocosm experiment with regular tidal regimes. Our results demonstrate that behavioral responses to heat stress strongly depend on the site-specific morphological features. Cockles covered by shallow water pools moved up when exposed to thermal stress, while burrowing deeper into the sediment in the absence of water pools. But in both cases, their migratory behavior increased under heat stress compared to regular ambient treatments. Moreover, long-term cumulative heat stress increased cockles' respiration rates and decreased their health conditions, causing mass mortality after four weeks of gradually increasing heat exposure. Overall, the present findings provide the first insights into how bioturbating behavior on tidal flats may change in response to global warming.

Tropical deforestation accelerates local warming and loss of safe outdoor working hours

<h2>Summary</h2> Climate change has increased heat exposure in many parts of the tropics, negatively impacting outdoor worker productivity and health. Although it is known that tropical deforestation is associated with local warming, the extent to which this additional heat exposure affects people across the tropics is unknown. In this modeling study, we combine worker health guidelines with satellite, reanalysis, and population data to investigate how warming associated with recent deforestation (2003–2018) affects outdoor working conditions across low-latitude countries, and how future global climate change will magnify heat exposure for people in deforested areas. We find that the local warming from 15 years of deforestation was associated with losses in safe thermal working conditions for 2.8 million outdoor workers. We also show recent large-scale forest loss was associated with particularly large impacts on populations in locations such as the Brazilian states of Mato Grosso and Pará. Future global warming and additional forest loss will magnify these impacts.

Perceptions of workplace heat exposure and adaption behaviors among Chinese construction workers in the context of climate change

BackgroundWorkplace heat exposure can cause a series of heat-related illnesses and injuries. Protecting workers especially those undertake work outdoors from the risk of heat strain is a great challenge for many workplaces in China under the context of climate change. The aim of this study is to investigate the perceptions and adaptation behaviors of heat exposure among construction workers and to provide evidence for the development of targeted heat adaptation strategies nationally and internationally.MethodsIn 2020, we conducted a cross-sectional online questionnaire survey via WeChat Survey Star in China, using a purposive snowball sampling approach. A total of 326 construction workers submitted completed questionnaires. The perceptions of workplace heat exposure were measured using seven indicators: concerns over high temperature, perception of high temperature injury, attitudes towards both heat-related training and regulations, adjustment of working habits during heat, heat prevention measures in the workplace, and reduction of work efficiency. Bivariate and multivariate regression analyses were used to identify the factors significantly associated with workers’ heat perceptions and behavioral responses.Results33.3% of the respondents were moderately or very concerned about heat exposure in the workplace. Less than half of the workers (43.8%) were worried about heat-related injuries. Workers who have either experienced work-related injuries (OR = 1.30, 95% CI 1.03–1.62) or witnessed injuries to others during high temperatures (OR = 1.12, 95% CI 1.02–1.27) were more concerned about heat exposure compared to other workers. Most respondents (63.5%) stated that their work efficiency declined during extremely hot weather. The factors significantly associated with a reduction of work efficiency included undertaking physically demanding jobs (OR = 1.28, 95% CI 1.07–1.54) and witnessing other workers’ injuries during high temperatures (OR = 1.26, 95% CI 1.11–1.43). More than half of the workers were willing to adjust their work habits to adapt to the impact of high temperatures (81.6%). The internet was the most common method to obtain heat prevention information (44.7%), and the most frequently used heat prevention measure was the provision of cool drinking water (64.8%).ConclusionsChinese construction workers lack heat risk awareness and are not well prepared for the likely increasing heat exposure in the workplace due to global warming. Therefore, there is a need to improve their awareness of heat-related injuries, strengthen high temperature related education and training, and update the current heat prevention policies to ensure compliance and implementation.

A vast increase in heat exposure in the 21st century is driven by global warming and urban population growth

Over the 21st century, human-caused climate change is projected to vastly increase the occurrence of severe heat, which has deleterious health, economic, and societal impacts. Over the same period, global human population is expected to increase from 7.8 to 10.9 billion, placing more people in harm's way. Here, we combine projections of sustained heat from climate models with spatially explicit population projection scenarios. We find that: (1) by 2090, high climate change and population growth scenarios show a ~5-, ~10-, and ~100–1000-fold increase in the population exposed to a mean hottest monthly temperature of 30 ºC, 35 ºC, and 40 ºC, respectively; (2) globally, population growth, warming, and their interaction, are the major drivers for the increase in exposure at milder, harsher, and extreme, temperatures, respectively; and (3) differences between population growth scenarios show that policy can potentially reduce the level of increase in exposure by up to 70%. Based on our analyses, the major driver for the increased heat exposure is the dangerous combination between global warming and population growth in already-warm cities in regions like Africa, India, and the Middle East.

The Effects of Heat Exposure During Intermittent Exercise on Physical and Cognitive Performance Among Team Sport Athletes.

This study investigated the effects of heat exposure on physical and cognitive performance during an intermittent exercise protocol so as to reflect the incremental fatigue experienced during team sports. Twelve well-trained male team sport players completed an 80-minute cycling intermittent sprint protocol (CISP), alongside computerized vigilance and congruent (i.e., simple) and incongruent (i.e., complex) Stroop tasks of cognitive functioning, in two counterbalanced temperature conditions; hot (32°C[50%rh]) and control (18°C[50%rh]). Incongruent Stroop accuracy declined over time (p = .002), specifically in the second (Mdiff = –3.75, SD = 0.90%, p = .009) and third (Mdiff = –4.58, SD = 1.22%, p = .019) quarters compared to the first quarter of the CISP; but there were no differences between temperature conditions. Congruent Stroop reaction time (RT) was quicker in the second quarter of exercise in the hot condition (M = 561.99, SD = 112.93 ms) compared to the control condition (M=617.80, SD = 139.71 ms; p = .022), but no differences were found for congruent Stroop accuracy nor vigilance measures. Additionally, peak power output was lower during the third quarter of the CISP in the hot condition (M = 861.31, SD = 105.20 W) compared to the control condition (M = 900.68, SD = 114.84 W; p < .001). Plasma normetanephrine and metanephrine concentrations increased from pre- to post-CISP (Mdiff = +616.90, SD = 306.99, p < .001; and Mdiff = +151.23, SD = 130.32, p = .002, respectively), with a marginal interaction suggesting a higher normetanephrine increase from pre- to post-CISP in the hot versus the control condition (p = .070). Our findings suggest that accuracy for more complex decisions suffered during prolonged high-intensity intermittent exercise, perhaps due to exercise-induced catecholamine increases. Athletes may have also reduced physical effort under increased heat exposure, indicating how cognitive performance may be sustained in physically demanding environments.

Physiological Changes During Five Days Of Heat Acclimation

The process of acclimation is imperative to ensure worker safety in hot environments. Most industry acclimation protocols prescribe 5 days of increasing heat exposure before working in the heat while research suggests 10-14 days for full acclimation. PURPOSE: To determine if 5 days of acclimation can induce meaningful physiological changes for worker safety. METHODS: Data collected from previous heat stress studies were used. A convenience sample of 15 female and 20 male participants (age = 28±6 yr, ht = 171±7.6 cm, wt = 76.7±16.4 kg) walked on a treadmill at a moderate metabolic rate (160 W/m2) in a hot environment (50°C and 20% RH; WBGT = 35.71°C) while wearing shorts, t-shirt and athletic shoes. Rectal temperature (Tre) and heart rate (HR) were monitored continuously throughout all trials. Trials lasted approximately 120 minutes or upon attainment of sustained HR greater than 90% of age-predicted HRmax, Tre> 39°C, or participant wished to stop. Paired samples t-tests were used to assess changes in ending HR and Tre over the last 2 days of acclimation. Repeated measures ANOVA were used to determine differences in Tre and HR over the acclimation period. Significance was set at p < 0.05. RESULTS: There was no significant difference in ending HR or ending Tre over the last 2 days of acclimation (p>0.05), suggesting participants were acclimated. Trial duration increased significantly from day 1 to day 5 (Time = 97±23 and 115±11 min, p=0.004). During the first trial, 18 participants (51.4%) were able to complete 120 min, and 25 participants (71.4% )were able to complete 120 min by the end of acclimation. Beginning Tre was not significantly different from Day 1 to Day 5 (p=0.106), however Day 1 ending Tre (38.35 ±0.51°C) was significantly higher than Day 5 (38.10± 0.66°C; P=0.039). Beginning HR was significantly greater for Day 1 than Day 5 (HR = 103±16 and 93±13 bpm; p = 0.024), but there was no significant difference in ending HR from day 1 to day 5 (p=0.056). CONCLUSION: Five days of acclimation can induce physiological changes in HR and Tre; specifically in resting HR and ending Tre. As such, industry acclimation protocols are adequate to induce physiological changes to help reduce heat illness.

Estimating near‐surface air temperature across Israel using a machine learning based hybrid approach

AbstractRising global temperatures over the last decades have increased heat exposure among populations worldwide. An accurate estimate of the resulting impacts on human health demands temporally explicit and spatially resolved monitoring of near‐surface air temperature (Ta). Neither ground‐based nor satellite‐borne observations can achieve this individually, but the combination of the two provides synergistic opportunities. In this study, we propose a two‐stage machine learning‐based hybrid model to estimate 1 × 1 km2 gridded intra‐daily Ta from surface skin temperature (Ts) across the complex terrain of Israel during 2004–2016. We first applied a random forest (RF) regression model to impute missing Ts from the Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua and Terra satellites, integrating Ts from the geostationary Spinning Enhanced Visible and InfraRed Imager (SEVIRI) satellite and synoptic variables from European Centre for Medium‐Range Weather Forecasts' (ECMWF) ERA5 reanalysis data sets. The imputed Ts are in turn fed into the Stage 2 RF‐based model to estimate Ta at the satellite overpass hours of each day. We evaluated the model's performance applying out‐of‐sample fivefold cross validation. Both stages of the hybrid model perform very well with out‐of‐sample fivefold cross validated R2 of 0.99 and 0.96, MAE of 0.42°C and 1.12°C, and RMSE of 0.65°C and 1.58°C (Stage 1: imputation of Ts, and Stage 2: estimation of Ta from Ts, respectively). The newly proposed model provides excellent computationally efficient estimation of near‐surface air temperature at high resolution in both space and time, which helps further minimize exposure misclassification in epidemiological studies.

Temperature-related excess mortality in German cities at 2 °C and higher degrees of global warming

BackgroundInvestigating future changes in temperature-related mortality as a function of global mean temperature (GMT) rise allows for the evaluation of policy-relevant climate change targets. So far, only few studies have taken this approach, and, in particular, no such assessments exist for Germany, the most populated country of Europe. MethodsWe assess temperature-related mortality in 12 major German cities based on daily time-series of all-cause mortality and daily mean temperatures in the period 1993–2015, using distributed-lag non-linear models in a two-stage design. Resulting risk functions are applied to estimate excess mortality in terms of GMT rise relative to pre-industrial levels, assuming no change in demographics or population vulnerability. ResultsIn the observational period, cold contributes stronger to temperature-related mortality than heat, with overall attributable fractions of 5.49% (95%CI: 3.82–7.19) and 0.81% (95%CI: 0.72–0.89), respectively. Future projections indicate that this pattern could be reversed under progressing global warming, with heat-related mortality starting to exceed cold-related mortality at 3 °C or higher GMT rise. Across cities, projected net increases in total temperature-related mortality were 0.45% (95%CI: −0.02–1.06) at 3 °C, 1.53% (95%CI: 0.96–2.06) at 4 °C, and 2.88% (95%CI: 1.60–4.10) at 5 °C, compared to today's warming level of 1 °C. By contrast, no significant difference was found between projected total temperature-related mortality at 2 °C versus 1 °C of GMT rise. ConclusionsOur results can inform current adaptation policies aimed at buffering the health risks from increased heat exposure under climate change. They also allow for the evaluation of global mitigation efforts in terms of local health benefits in some of Germany's most populated cities.

Thermal Exposure Limit in a Simulated Refuge Alternative

Federal standards for refuge alternatives (RAs) mandate that they not exceed a Steadman apparent temperature (AT) of 95 °F (35 °C) at an assumed metabolic rate of 325 W, a limit that appears to be arbitrary. Occupants in an RA spend most of their time at rest (a metabolic rate less than 325 W), and thermal equilibrium can likely be maintained at an AT > 35 °C. The purpose of this study was to examine the upper limit of sustainable heat stress during 4- and 8-h exposures at rest. Five men underwent five 4-h trials (phase 1: AT range 39 to 49 °C, 90% rh) and five 8-h trials (phase 2: AT range 46 to 56 °C, 90% rh) in a semi-recumbent position. Descriptive statistics for gastrointestinal temperature (Tgi), heart rate (HR), systolic and diastolic blood pressure (SBP and DBP), sweat rate, fluid intake, urine color, urine specific gravity (USG), and changes in body mass are reported. Mean Tgi for all trials ranged from 36.9 to 37.3 °C, and mean HR for all trials ranged from 61 to 75 bpm. To determine the effects of increased heat exposure, differences in heat strain between 4- and 8-h trials were examined via repeated measures analysis of variance (ANOVA). As AT increased, there were no significant changes in ΔTgi and ΔHR from 1 to 4 h in the 4-h and 8-h trials. During the 8-h trials, as AT increased, there was a difference in ΔTgi between 4 and 8 h. In conclusion, there was support for sustainable exposures resulting in no significant increase in physiological strain at an AT greater than 35 °C AT, with a sustainable limit (no increases in Tgi due to increases in AT) below 46 °C AT. Although the participants were not representative of coal miners, the results provide support for sustainable exposures greater than 35 °C AT at an average metabolic rate of 155 W.

Heat Exposure and Occupational Injuries: Review of the Literature and Implications.

The burden of heat-related adverse occupational health effects, as well as traumatic injuries, is already substantial. Projected increases in mean temperatures and extreme events may increase the risk of adverse heat health effects and enhance disparities among exposed workers. This article reviews the emerging literature on the relationship between heat exposure and occupational traumatic injuries and discusses implications of this work. A recent meta-analysis of three case-crossover and five time series studies in industrialized settings reported an association of increasing occupational injuries with increasing heat exposure, with increased effect estimates for male gender and age less than 25years, although heterogeneity in exposure metrics and sources of bias were demonstrated to varying degrees across studies. A subsequent case-crossover study in outdoor construction workers reported a 0.5% increase in the odds of traumatic injuries per 1°C increase in maximum daily humidex (odds ratio 1.005 [95% CI 1.003-1.007]). While some studies have demonstrated reversed U-shaped associations between heat exposure and occupational injuries, different risk profiles have been reported in different industries and settings. Studies conducted primarily in industrialized settings suggest an increased risk of traumatic injury with increasing heat exposure, though the exact mechanisms of heat exposure's effects on traumatic injuries are still under investigation. The effectiveness of heat-related injury prevention approaches has not yet been established. To enhance the effectiveness of prevention efforts, prioritization of approaches should take into account not only the hierarchy of controls, social-ecological models, community and stakeholder participation, and tailoring of approaches to specific local work settings, but also methods that reduce local and global disparities and better address the source of heat exposure, including conservation-informed land-use planning, built environment, and prevention through design approaches. Participation of occupational health experts in transdisciplinary development and integration of these approaches is needed.

Interacting implications of climate change, population dynamics, and urban heat mitigation for future exposure to heat extremes

One near-term expression of climate change is increased occurrence and intensity of extreme heat events. The evolution of extreme heat risk in cities depends on the interactions of large-scale climate change with regional dynamics and urban micro-climates as well as the distribution and demographic characteristics of people who live and work within these micro-climate areas. Here we use California as a testbed where we employ a suite of high-resolution (1.5 km) future regional climate simulations coupled with a satellite-driven urban canopy model and a spatially explicit population projection to investigate the interacting effects of climate change, population growth, and urban heat mitigation measures, such as cool roofs, on exposure to extreme heat events. We find that climate change and population growth reinforce with one another to drive substantial increases in future exposure to heat extremes, which are poised to become more frequent, longer, and more intense. Exposure to events analogous to historic high-mortality extreme heat waves increases by 3.5–6 folds. Widespread implementation of cool roofs can offset a substantial fraction (51%–100%) of the increased heat exposure and associated building energy demand owing to climate change in urbanized regions.

Improvement of flexural strength and compressive strength by heat treatment of PLA filament for 3D-printing

Poly-lactic Acid (PLA) is an environmentally friendly material with better stability in heat shrinkage than Acrylonitrile Butadiene Styrene (ABS), such as warping in 3D printing. This study focused on the enhancement of the mechanical properties of PLA filament for 3D printers through different heat treatment temperature and heat exposure time of PLA samples. The results showed that the highest flexural strength was recorded in the PLA sample that went through heat treatment at [Formula: see text] and heat exposure time of 300 s. And it tended to decrease with temperature and time after this point. But it has higher flexural strength than neat PLA. The compressive strength showed the highest compressive strength through heat treatment at [Formula: see text] for 600 s. Because compressive strength has no threshold limit temperature in experimental temperature, compressive strength showed a tendency to increase with increasing heat exposure time and high temperature at same condition. This result showed that the heat treatment process affects the flexural strength and compressive strength and can be improved upon using appropriate heat treatment conditions.