Extreme Ambient Temperatures Research Articles

Exposure to acute ambient temperature extremes and neonatal intensive care unit admissions: A case-crossover study

BackgroundExtreme in utero temperatures have been associated with adverse birth outcomes, including preterm birth and low birthweight. However, there is limited evidence on associations with neonatal intensive care unit (NICU) admissions, which reflect a range of poor neonatal health outcomes. MethodsThis case-crossover study assesses the associations between ambient temperature changes during the week of delivery and risk of NICU admission. Data from the Consortium on Safe Labor (2002–2008) were linked to ambient temperature at hospital referral regions. Adjusted hazard ratios (HR) and 95 % confidence intervals (CI) estimated NICU admission risk with a 1 °C increase on each day of the week of delivery and of the average weekly temperature, adjusted for particulate matter ≤2.5 μm (PM2.5) and relative humidity. We also estimated associations with 1 °C increases and 1 °C decreases in temperatures during weeks of site-specific extreme heat (>90th and 95th percentiles) and cold (<5th and 10th percentiles), respectively. ResultsThere were 27,188 NICU admissions with median (25th, 75th) temperature of 16.4 °C (5.8, 23.0) during the week before delivery. A 1 °C increase in temperature during the week of delivery was not associated with risk of NICU admission. However, analyses of extreme temperatures found that a 1 °C decrease in weekly average temperatures below the 10th and 5th percentiles was associated with 30 % (aHR = 1.30, 95 % CI 1.28, 1.31) and 47 % (aHR = 1.47, 95 % CI 1.45, 1.50) increased risk of NICU admissions, while a 1 °C increase in weekly average temperatures above the 90th and 95th percentiles was associated with more than two- (aHR = 2.29, 95 % CI 2.17, 2.42) and four-fold (aHR = 4.30, 95 % CI 3.68, 5.03) higher risk of NICU admission, respectively. ConclusionsOur study found temperature extremes in the week before delivery increased NICU admission risk, particularly during extreme heat, which may translate to more adverse neonatal outcomes as extreme temperatures persist.

Climate Change and Congenital Anomalies: A Population-Based Study of the Effect of Prolonged Extreme Heat Exposure on the Risk of Neural Tube Defects in France.

Exposure to long-lasting extreme ambient temperatures in the periconceptional or early pregnancy period might increase the risk of neural tube defects (NTDs). We tested whether prolonged severe heat exposure as experienced during the 2003 extreme heatwave in France, affected the risk of NTDs. We retrieved NTD cases spanning from January 1994 to December 2018 from the Paris Registry of Congenital Malformations. The 2003 heatwave was characterized by the long duration and high intensity of nine consecutive days with temperatures ≥35°C. We classified monthly conceptions occurring in August 2003 as "exposed" to prolonged extreme heat around conception (i.e., periconceptional period). We assessed whether the risk of NTDs among cohorts exposed to the prolonged severe heatwave of 2003 in the periconceptional period differed from expected values using Poisson/negative binomial regression. We identified 1272 NTD cases from January 1994 to December 2018, yielding a monthly mean count of 4.24. Ten NTD cases occurred among births conceived in August 2003. The risk of NTD was increased in the cohort with periconceptional exposure to the August 2003 heatwave (relative risk = 2.14, 95% confidence interval: 1.46 to 3.13), compared to non-exposed cohorts. Sensitivity analyses excluding July and September months or restricting to summer months yielded consistent findings. Evidence from the "natural experiment" of an extreme climate event suggests an elevated risk of NTDs following exposure to prolonged extreme heat during the periconceptional period.

A novel multifunctional electrolyte system for high performance Li-ion batteries

Lithium-ion batteries have advantages such as environmental protection and sustainable use, but the widespread application of lithium-ion battery-powered vehicles is limited by the inability to quickly charge and extreme ambient temperatures, and reasonable design of electrolyte components can effectively solve these problems. Here, a novel fluoroethylene carbonate (FEC)/ethyl acetate (EA) based electrolyte containing lithium difluorophosphate (LiPO2F2, 2 wt%) and lithium bis(fluorosulfonyl)imide salt (LiFSI, 1.0 M) is first reported. The electrolyte containing these components has the characteristics of low freezing point, low viscosity and high ionic conductivity. Especially, due to the preferential decomposition of FEC, LiFSI and LiPO2F2, uniform multiphase inorganic LiF and Li3N species are formed on the electrode surface with enhanced robustness and ion transfer kinetics. So, the graphite||LiNi0.5Co0.2Mn0.3O2&LiMn2O4 (Gr||LMO&NCM523) batteries in the designed electrolyte maintain high capacity and coulombic efficiency (100 %) after 200 times at 1C charge and discharge current density at 25 °C and 45 °C. At −20 °C, the batteries have a coulombic efficiency of 50 % and capacity of 38.0 mA h g−1 after 200 charging and discharging cycles, showing excellent low-temperature fast dynamics. Our work supplies an efficient way to accelerate the engineering application of Li-ion batteries.

Experimental study on axial compression performance of circular CFST columns considering extreme ambient temperature

To examine CFST short columns’ mechanical properties under extreme temps, 14 specimens were designed, focusing on temp’s impact on materials. Axial compression tests revealed temp-dependent changes: concrete strength surged at low temps but ductility diminished, while steel’s properties stayed stable. Concrete strength gains boosted columns’ strength, enhancing steel-concrete synergy. Shear failure dominated at low temps. Ductility improved with thinner diameters or wetter mixes. Calculations underestimated actual capacity, likely due to temperature neglect in design codes, EC4 most notably. Finally, incorporating the experimental results, the bearing capacity calculation formula of CFST based on the unified theory was modified and accounts for ambient temperature.

Prenatal exposure to extreme ambient temperatures and risk of neurodevelopmental disorders: a cohort study in Ontario, Canada

Prenatal exposure to extreme ambient temperatures and risk of neurodevelopmental disorders: a cohort study in Ontario, Canada

Mortality risk and burden of sudden cardiac arrest associated with hot nights, heatwaves, cold spells, and non-optimum temperatures in 0.88 million patients: An individual-level case-crossover study

Sudden cardiac arrest (SCA) is a global health concern, imposing a substantial mortality burden. However, the understanding of the impact of various extreme temperature events, when accounting for the effect of daily average temperature on SCA, remains incomplete. Additionally, the assessment of SCA mortality burden associated with temperatures from an individual-level design is limited. This nationwide case-crossover study collected individual SCA death records across all (2844) county-level administrative units in the Chinese Mainland from 2013 to 2019. Four definitions for hot nights and ten for both cold spells and heatwaves were established using various temperature thresholds and durations. Conditional logistic regression models combined with distributed lag nonlinear models were employed to estimate the cumulative exposure-response relationships. Based on 887,662 SCA decedents, this analysis found that both hot nights [odds ratio (OR): 1.28; attributable fraction (AF): 1.32 %] and heatwaves (OR: 1.40; AF: 1.29 %) exhibited significant added effects on SCA mortality independent of daily average temperatures, while cold spells were not associated with an elevated SCA risk after accounting for effects of temperatures. Cold temperatures [below the minimum mortality temperature (MMT)] accounted for a larger mortality burden than high temperatures (above the MMT) [AF: 12.2 % vs. 1.5 %]. Higher temperature-related mortality risks and burdens were observed in patients who experienced out-of-hospital cardiac arrest compared to those with in-hospital cardiac arrest. This nationwide study presents the most compelling and comprehensive evidence of the elevated mortality risk and burden of SCA associated with extreme temperature events and ambient temperatures amid global warming.

Maternal exposure to ambient temperature and birth defects in Brazil: a nationwide case-control study of over 11 million newborns.

Maternal exposure to extreme ambient temperature during pregnancy has been proposed as a potential risk factor for birth defects. Comprehensive investigations on this association remain limited, particularly in low- and middle-income countries. This study aims to examine the association between ambient temperature exposure during pregnancy and the risk of birth defects in Brazil, contributing to the broader understanding of environmental influences on birth outcomes. Using a large dataset of over 11 million live birth records, we analyzed 12 categories of birth defects, encompassing a time frame from 2001 to 2018. Ambient temperature data were assigned at the municipality level. For the exposure assessment, we considered two biologically driven pregnancy stages by dividing the gestational period into two specific windows: the first trimester (from week 1 to week 12) and the second trimester (from week 13 to week 28). We employed a two-stage case-control design. In the first stage, we applied a conditional logistic regression model to estimate the odds ratio (OR) for specific birth defects and each of the five Brazilian regions (North, Northeast, Midwest, Southeast, and South). The model was adjusted for potential confounding variables, including PM2.5, relative humidity, and socioeconomic status. Temporal trends were addressed using time-stratified sampling. In the second stage, we used mixed-effects meta-analysis to pool region-specific estimates. Our analysis revealed a significant association between maternal exposure to higher ambient temperatures during the first trimester and an increased risk of specific birth defect categories, including those affecting the genital organs (OR = 1.08, 95% CI: 1.02; 1.14), digestive system (OR = 1.12, 95% CI: 1.06; 1.19); circulatory system (OR = 1.08, 95% CI: 1.01; 1.17); eyes, ears, face, and neck (OR = 1.08, 95% CI: 1.02; 1.15); benign neoplasms tumors (OR = 1.17, 95% CI: 1.03; 1.32), musculoskeletal system (OR = 1.03, 95% CI: 1.01; 1.05); and other congenital anomalies (OR = 1.22, 95% CI: 1.15; 1.29). The associations with respiratory system, nervous system, and chromosomal anomalies were null. These findings have significant implications for public health policies aimed at mitigating the impact of environmental factors on birth outcomes, both in Brazil and globally.

Research on thermal runaway characteristics and mechanism of NCM811 Lithium-ion batteries under cross-seasonal and wide-temperature condition at −10 °C ∼ 33 °C: A case study in Qingdao, China

Multiple heat sources and extreme ambient temperatures pose more severe challenges to the safety performance of lithium-ion batteries (LIBs), and the kinetic characterization of thermal runaway (TR) of LIBs at extreme temperatures has yet to be improved. Through the establishment of a dual heat source coupled stimulation experimental platform, this study investigates the TR mechanism and flame jet dynamics of LIBs under broad temperature ranges corresponding to spring, summer, autumn, and winter (−10 °C ∼ 30 °C). The results indicate that the increase in ambient temperature leads to a gradual reduction in the TR onset time (tonset), in the order of Tonset-Winter>Tonset-Spring>Tonset-Autumn>Tonset-Summer; for example, with 100% SOC (State of Charge), Tonset-Winter = 2528 s, Tonset-Summer = 2211 s, which was accelerated by 14.3%. However, TR maximum temperature (Tmax) showed the opposite trend, Tmax-summer = 687.2 °C, Tmax-winter = 796.5 °C, which decreased by 15.9%. When SOC ≥ 75%, the average warning time for TR disaster of LIB (from venting to the beginning of TR) is 254 s less than that of winter in the summer with higher temperature, which makes the adoption of emergency measures and escape more urgent. When SOC ≥ 50%, the TR process was accompanied by flame generation, and the flame eruption process was the most intense at 100% SOC, with a maximum flame area of about 4400 cm2, and its flame temperature was likewise the highest at 986.4 °C. Carbon and metal oxides were detected in the TR ejecta, and the lower the ambient temperature, the finer the ejecta particles were. The results of the study provide an important scientific reference for improving the theory of TR of LIBs, guiding the investigation of TR and fire in new energy vehicles, and formulating relevant standards.

Solar-assisted biogas system with air-source heat pump for the energy-saving of indoor heating in north China

Abstract To address the challenges associated with winter heating in high-latitude regions of China, solar-assisted biogas heating systems have emerged as the predominant focus of research due to their cost-effectiveness, accessibility, and environmentally friendly attributes. However, traditional solar-assisted biogas heating systems encounter issues of low efficiency and limited practicality resulting from unstable solar radiation and extreme ambient temperatures during the heating season. To improve the economy and stability of the system, this study proposed a novel operational control method for a small-scale energy station system in rural regions of North China, named Solar-Biomass-Air Source Heat Pump Hybrid Heating System (SBHP-HHS). The integration of solar energy, biogas energy, and air-source heat pump (ASHP) systems in this proposed work has shown to create effective complementarity and enhances the production efficiency of the existing system. Test and simulation studies have been carried out for this system. The layout of buildings and equipment within a university campus in Beijing is reconfigured and redesigned, incorporating an ASHP into the existing heat source configuration. To begin with, a mathematical model is established for the complementary heating system that incorporates solar energy, a biogas digester, and an ASHP. Subsequently, a dynamic simulation model is developed using the TRNSYS platform, and a corresponding operational control strategy for the multi-energy complementary heating system is proposed. Dynamic simulation and analysis of the newly implemented system are performed using the TRNSYS platform, focusing on energy flow and thermodynamic performance. Throughout the heating season, the solar-biogas integrated system achieves a remarkable assurance rate of up to 79%. Additionally, ASHP maintains a relatively high heating efficiency, coefficient of performance (COP) reaches 3.02. Finally, an economic evaluation of the multi-energy complementary system was conducted based on the annual cost method. This was compared with the clean approach of using only an ASHP unit. The results indicate that the SBHP-HHS is more economical when the anticipated useful life is 6 years or longer. The results indicate that the proposed can achieve significant energy-saving and carbon-reduction benefits in rural areas, catering to their heating needs.

Association of sudden sensorineural hearing loss with meteorological factors: a time series study in Hefei, China, and a literature review

Air pollution can cause disease and has become a major global environmental problem. It is currently believed that air pollution may be related to the progression of SSNHL. As a rapidly developing city in recent years, Hefei has serious air pollution. In order to explore the correlation between meteorological variables and SSNHL admissions, we conducted this study. This study investigated the short-term associations between SSNHL patients admitted to the hospital and Hefei climatic variables. The daily data on SSNHL-related hospital admissions and meteorological variables containing mean temperature (T-mean; °C), diurnal temperature range (DTR; °C), atmospheric pressure (AP; Hp), and relative humidity (RH; %), from 2014 to 2021 (2558 days), were collected. A time-series analysis integrating distributed lag non-linear models and generalized linear models was used. PubMed, Embase, Cochrane Library, and Web of Science databases were searched. Literature published up to August 2023 was reviewed to explore the potential impact mechanisms of meteorological factors on SSNHL. The mechanisms were determined in detail, focusing on wind speed, air pressure, temperature, humidity, and air pollutants. Using a median of 50.00% as a baseline, the effect of exceedingly low T-mean in the single-day hysteresis effect model began at a lag of 8 days (RR = 1.032, 95% CI: 1.001 ~ 1.064). High DTR affected the admission rate for SSNHL on lag 0 day. The significance of the effect was the greatest on that day (RR = 1.054, 95% CI: 1.007 ~ 1.104) and then gradually decreased. High and exceedingly high RH affected the admission rate SSNHL on lag 0 day, and these effects lasted for 8 and 7 days, respectively. There were significant associations between all grades of AP and SSNHL. This is the first study to assess the effect of meteorological variables on SSNHL-related admissions in China using a time-series approach. Long-term exposures to high DTR, RH values, low T-mean values, and all AP grades enhance the incidence of SSNHL in residents. Limiting exposure to extremes of ambient temperature and humidity may reduce the number of SSNHL-related hospital visits in the region. It is advisable to maintain a suitable living environment temperature and avoid extreme temperature fluctuations and high humidity. During periods of high air pollution, it is recommended to stay indoors and refrain from outdoor exercise.

Associations between heat wave during pregnancy and term birth weight outcomes: The PARIS birth cohort

BackgroundClimate change will make extreme weather events more frequent in the 21st century. Extreme ambient temperatures during the prenatal period have been associated with adverse pregnancy outcomes such as preterm birth. It is unclear, however, whether heat waves during pregnancy impact fetal growth in apparently healthy term newborns. ObjectivesWe aimed to investigate associations between heat wave during pregnancy and birth weight outcomes in term newborns from the PARIS birth cohort, and to explore meteorological conditions and air pollution as possible intermediate factors. MethodsWe examined data on 3,359 newborns born between 37 and 42 weeks in Paris, France, between 2003 and 2006. Associations of maternal exposure to heat wave (during whole pregnancy and each trimester) with birth weight and small for gestational age (SGA) at term were studied using linear and logistic regression models adjusted for potential confounders. Maternal characteristics were investigated as possible modifiers. We explored the mediating role of ambient temperature, relative humidity, and air pollution levels in the relationship between heat wave during the first trimester and term SGA. ResultsMothers who were pregnant during the 2003 French heat wave (n = 506, 15 %) were more likely to have a term SGA baby (aOR = 2.70; 95 %CI: 1.38, 5.28) compared to mothers who did not experience heat wave during pregnancy. The association was stronger when heat wave occurred during the first trimester (aOR = 4.18; 95 %CI: 1.69, 10.35). Primiparous women were identified as more vulnerable than multiparous women. Average ambient temperature and air quality index explained about 36 % and 56 % of the association between heat wave during the first trimester and term SGA, respectively. ConclusionsThis study suggests prenatal exposure to heat wave, especially during the first trimester, may adversely affect fetal growth of term newborns, which could be explained by both increasing ambient temperatures and worsening air quality.

Experimental investigation of high-temperature heating in open-loop air cycle heat pump system utilizing compressed gas waste energy recovery

Recycling waste energy from compressed gases has consistently been a focal point in the field of energy conservation. This paper presents a novel open-loop air cycle heat pump system designed to recover waste energy from compressed gases. The system maintains stable operation and provide hot water above 80 °C even under extreme ambient temperatures (below −30 °C), thereby catering to diverse heating needs across a wide temperature spectrum. Experimental results show that, when the ambient temperature varies from 10 °C to −20 °C, the heating capacity and water temperature difference between inlet and outlet only decrease by 4.82% and 4.99% respectively, suggesting negligible impact. However, when water flow rate varies from 4 m3/h to 10 m3/h, the heating capacity marginally increases by 3.35% while the water temperature difference between inlet and outlet significantly decreases by 141.95%. Continuous increase of inlet water temperature Tw, in at 0.40 °C·min−1 results in an initial 10% decrease of heating capacity, following which the system automatically adjusts to another stable operational state of around 50 kW heating capacity. This transition has minimal effect on the water temperature difference between inlet and outlet and temperature rise rate of outlet water temperature. The expansion work recovery efficiency of turbine-compressor coupled module is approximately 90%.

Investigation of heat stress responses and adaptation mechanisms by integrative metabolome and transcriptome analysis in tea plants (Camellia sinensis).

Extreme high temperature has deleterious impact on the yield and quality of tea production, which has aroused the attention of growers and breeders. However, the mechanisms by which tea plant varieties respond to extreme environmental heat is not clear. In this study, we analyzed physiological indices, metabolites and transcriptome differences in three different heat-tolerant tea plant F1 hybrid progenies. Results showed that the antioxidant enzyme activity, proline, and malondialdehyde were significantly decreased in heat-sensitive 'FWS' variety, and the accumulation of reactive oxygen molecules such as H2O2 and O2- was remarkably increased during heat stress. Metabolomic analysis was used to investigate the metabolite accumulation pattern of different varieties in response to heat stress. The result showed that a total of 810 metabolites were identified and more than 300 metabolites were differentially accumulated. Transcriptional profiling of three tea varieties found that such genes encoding proteins with chaperon domains were preferentially expressed in heat-tolerant varieties under heat stress, including universal stress protein (USP32, USP-like), chaperonin-like protein 2 (CLP2), small heat shock protein (HSP18.1), and late embryogenesis abundant protein (LEA5). Combining metabolomic with transcriptomic analyses discovered that the flavonoids biosynthesis pathway was affected by heat stress and most flavonols were up-regulated in heat-tolerant varieties, which owe to the preferential expression of key FLS genes controlling flavonol biosynthesis. Take together, molecular chaperons, or chaperon-like proteins, flavonols accumulation collaboratively contributed to the heat stress adaptation in tea plant. The present study elucidated the differences in metabolite accumulation and gene expression patterns among three different heat-tolerant tea varieties under extreme ambient high temperatures, which helps to reveal the regulatory mechanisms of tea plant adaptation to heat stress, and provides a reference for the breeding of heat-tolerant tea plant varieties.

Determination of polymorphisms in the HSP90AA1 gene region in some Turkish sheep populations by AS-PCR

Heat shock proteins (HSPs) are molecular chaperones protecting living cells from the negative effects of extreme ambient temperatures. In this study, genetic polymorphisms of the HSP90AA1 gene were monitored via Allele-Specific Polymerase Chain Reaction (AS-PCR) in three native Turkish sheep populations namely İvesi (IVS), Güney Karaman (GKR), and Karakaş (KRK). The HSP90AA1 was polymorphic in all populations yielding two alleles (C and G) and three genotypes (CC, CG, and GG). The G allele frequency was higher than the C allele frequency in all populations. The lowest (0.100) and highest (0.246) CC frequency was observed in KRK and IVS, respectively, while the GG genotype frequency varied between 0.250 (GKR) and 0.600 (KRK). Significant deviation (p&amp;lt;0.001) from Hardy-Weinberg Equilibrium (HWE) was detected in the IVS breed in terms of the HSP90AA1 gene. The genetic distance-based phylogenetic tree indicated that GKR was genetically different from IVS and KRK populations in terms of the HSP90AA1 polymorphism. These variations regarding the HSP90AA1 gene should be conserved, since the negative effects of global warming and climate change are expected to be more hazardous in the future. Besides, these genetic variations may be utilized by the farmers to design comprehensive selection strategies against heat stress in native Turkish sheep populations.

Global, regional, and national burden of stroke attributable to extreme low temperatures, 1990-2019: A global analysis.

Extreme ambient temperatures have been linked to increased risks of stroke morbidity and mortality. However, global estimates of the burden of stroke due to extreme low temperatures are not well-defined. This study aimed to determine the global burden of stroke due to extreme low temperatures and its spatiotemporal trend from 1990 to 2019. Based on the Global Burden of Disease Study 2019, we obtained global, regional, and national data on deaths, disability-adjusted life years (DALYs), age-standardized mortality rate (ASMR), and age-standardized rate of DALYs (ASDR) of stroke attributed to extreme low temperatures, further stratified by age, sex, and sociodemographic index (SDI). Globally, in 2019, an estimated 474,000 stroke deaths with the corresponding ASMR (6.2 (95% uncertainty interval (UI): 4.6-7.9)) and ASDR (103.9 (95% UI: 77.0-134.5)) per 100,000 population, were attributable to extreme low temperatures. The most significant burden was observed in Central Asia, followed by Eastern Europe and East Asia. From 1990 to 2019, the global burden of stroke and its subtypes (ischemic stroke, intracerebral hemorrhage, and subarachnoid hemorrhage) attributable to extreme low temperatures exhibited a decrease in both ASMR and ASDR. Significant decreases in stroke burden occurred in the high-SDI regions, high-income Asia Pacific, and subarachnoid hemorrhage cases. Moreover, the ASMR and ASDR increased with age and were higher in males than females. The global stroke burden due to extreme low temperatures remains high despite a decreasing trend over the past three decades. The stroke burden due to extreme low temperatures was more notable for Central Asia, older people, and the male sex.

Impairment on fillet fatty acid profile and oxidative damage in pirarucu, Arapaima gigas, acutely exposed to extreme ambient temperature

Climatic events are affecting the Amazon basin and according to projections it is predicted the intensification of climate changes through increases in temperature and carbon dioxide (CO2). Recent evidence has revealed that exposure to an extreme climate scenario elicits oxidative damage in some fish species, impairing their metabolism and physiology, contributing to their susceptibility. Thus, the comprehension of physiological alterations in Arapaima gigas (pirarucu) to the climatic changes forecasted for the next 100 years is important to evaluate its capability to deal with oxidative stress. The objective of this work was to determine whether antioxidant defense system is able to prevent muscle oxidative damage of pirarucu exposed 96 h to extreme climate scenario, as well as the effects of this exposition on muscle fatty acid levels. Lipid peroxidation and reactive oxygen species significantly increase in the muscle of pirarucus exposed to an extreme climate scenario compared to control, while muscle superoxide dismutase, catalase, and glutathione peroxidase were significantly lower. Total amount of saturated fatty acids (SFAs) was significantly higher in pirarucu exposed to an extreme climate scenario compared to control, while total content of monounsaturated (MUFAs) and polyunsaturated fatty acids (PUFAs) was significantly lower. Exposure to an extreme climate scenario causes muscular oxidative stress and that the antioxidant systems are inefficient to avoid oxidative damage. In addition, the increase of total SFAs and the decrease of MUFAs and PUFAs probably intend to maintain membrane fluidity while facing high temperature and CO2 levels.

The association between ambient temperature and semen quality in a Northern Peninsular Province, China.

Extreme ambient temperature has been linked to decline in males' semen quality. Although the temperature-semen quality association has been examined in certain cities of South China, how the effect size of the extreme temperature may lag over critical windows in spermatogenesis and whether the strength of association may vary in North China have yet been adequately explored. To quantify the association between air temperature and semen quality, and identify critical exposure windows in a Northern Peninsular Province, China. Data on semen quality in 2014-2019 were collected from the Human Sperm Bank of Institute of Women, Children and Reproductive Health, Shandong University, China. Daily meteorological data (0.01°×0.01°) were assigned to each subject's residential address. The linear mixed-effect model combined with the distributed lag nonlinear model was used to estimate the effect of ambient temperature over critical spermatogenesis windows. The temperature-semen quality association was inverted V-shaped, with the maximum lag being 0-45 days before ejaculation and the threshold being 9.2°C. Progressively and total motile sperm number, and total sperm number declined more substantially than other semen quality parameters. Semen quality was more sensitive to cold exposure during the epididymal storage period than the sperm motility development period. By contrast, semen quality was insensitive to heat exposure during both critical spermatogenesis windows. Impairment of certain semen quality parameters was more obvious for males with higher educational attainment and those aged over 35 years. Exposure to non-optimal temperature is associated with decreased semen quality in North China, with the epididymal storage and sperm motility development periods more sensitive to cold exposure than heat. Older males and those with higher educations may need particular awareness.

Relationship of environmental exposure temperature and temperature extremes on sperm DNA fragmentation index in men with different BMI values and the indirect effect of DNA fragmentation index on semen parameters

Prior studies have established a significant correlation between the DNA fragmentation index (DFI) and infertility. Additionally, certain investigations suggest that environmental exposure may serve as an etiological factor impacting semen quality. This study aimed to explore the impact of season, ambient temperature, and weather extremes on the DFI of sperm, along with other relevant parameters. Furthermore, it sought to assess how ambient temperature affects the DFI of sperm and other semen parameters in populations with varying BMI values. Additionally, the study analyzed the transient indirect effect of DFI on sperm parameters. This retrospective study analyzed semen samples from 11,877 men, selected based on female factor considerations, spanning from January 2016 to December 2021. Participants were grouped according to the season of semen collection. The results showed that samples collected in summer had a lower semen volume and sperm motility, while those collected in autumn had a lower DFI. We analyzed the exposure-response ratio between environmental exposure temperature and semen parameters using a generalized additive model. Results showed that the curve of the exposure-response relationship was U-shaped or inverted U-shaped; when the air temperature exposure was below the threshold, for each degree of temperature increase, the total sperm motility, sperm concentration, and progressive motility increased by 0.16 %, 0.29 × 10 (Levine, 1999)/ml and 0.14 %, respectively, while the DFI and inactivity rate decreased by 0.078 % and 0.15 %, respectively. When the air temperature exposure exceeded the threshold, for each degree of temperature increase, the sperm concentration, total sperm motility, semen volume and progressive motility decreased by 0.42 × 10 (Levine, 1999)/ml, 0.11 %, 0.0078 ml and 0.15 %, respectively, while the DFI and inactivity rate increased by 0.13 % and 0.12 %, respectively. Extremely cold weather during spermatogenesis was positively correlated with DFI, and extremely hot weather was negatively correlated with sperm motility. Subgroup analysis revealed that individuals classified as overweight / obese exhibited more pronounced changes in sperm parameters and the DFI in response to variations in environmental exposure temperature compared to those with a normal BMI. In the analysis of the relationship between DFI and sperm parameters, the results showed an inverted U-shape relationship between DFI and semen volume, and a negative correlation between DFI and sperm concentration and sperm motility. And we found that ambient temperature affects sperm parameters through DFI at low as well as average temperatures, whereas at high temperatures this indirect effect is no longer present.

Heat-related illnesses: advice for clinicians and healthcare professionals

The increase in heatwaves, a significant consequence of global warming, represents a major public health issue and is the main cause of death related to hyperthermia. The seriousness of such exposure to extreme ambient temperature lies in the difficulty to the general population to identify the warning signs and take appropriate protective measures. This article therefore presents guidelines for the prevention, recognition and treatment of heat-related illnesses, and thus arms clinicians and healthcare professionals who are on the front line in protecting the general population from this 'silent killer'.

An Evidence-Based Algorithm of Management of Heatstroke in the Emergency Department.

Annual rates of heat illness and heat-related deaths have been increasing across the United States as more regions of the country have been experiencing heat waves of extreme ambient temperatures of prolonged durations. According to the Centers for Disease Control and Prevention, heat illnesses have become the leading cause of weather-related deaths. This article critiques and describes the findings of a systematic review by C. Rublee et al. (2021). The review was conducted to develop an evidence-based algorithm specific for management of heatstroke in the emergency department with implications for improving recognition, initiating rapid cooling, and providing supportive care to reduce patient mortality and morbidity.