[5 cases of occupational heat illness].

Objective: Through the analysis of five cases of occupational heat illness caused by high temperature, we expounded the pathogenesis and summarized the clinical characteristics of heat cramp and heat exhaustion of the newly revised diagnostic criteria for occupational heat illness (GBZ41-2019), in order to prevent the occurrence of occupational heat illness to put forward controllable countermeasures. Methods: According to the occupational history, clinical diagnosis and treatment and the other relevant data submitted by five patients, the diagnosis process was analyzed and summarized. Results: Five patients developed symptoms from July to August in summer, belonging to high-temperature operation. They improved by timely treatment. The symptoms, signs and laboratory tests of the five patients were different, but they were diagnosed as occupational heat illness. Conclusion: Employers should pay attention to the high temperature protection and cooling work, and strengthen the labor protection. If patients with heat cramp and heat exhaustion were timely treated, they could basically recover. Occupational disease diagnosticians should seriously study the new diagnostic criteria of occupational disease and constantly improve their diagnostic ability.

Diagnosis and Management of Heatstroke.

Heatstroke is a life-threatening  and the most severe form of heat-related illnesses, characterized by body temperature >40ºC and central nervous system dysfunction. Heatstroke is classified into Non-Exertional Heatstroke (NEHS) and Exertional Heatstroke (EHS). The pathophysiology of heatstroke involves a combination of direct heat effects on the host, the systemic inflammatory and coagulopathic response. The diagnosis of heatstroke based on Bouchama's definition or Japan Association of Acute Medicine (JAAM) criteria. The basic principle of heatstroke management is early resuscitation and immediate cooling. Cold water immersion or convection evaporation method can be implemented based on the specific patient characteristic. Preventive strategies are early recognition by health workers, socialization to vulnerable groups and adequate acclimatization.

Health risks and precautions for visitors to the Tokyo 2020 Olympic and Paralympic Games.

BACKGROUND: In 2020, Japan will host the Tokyo Olympic and Paralympic Games in 2020 (Tokyo 2020) which will involve a large population influx from various countries to Tokyo, the most populated city in Japan. We summarize the potential health risks for visitors to Tokyo 2020, related to communicable disease risks and other health threats, based on recent national and local surveillance reports. METHODS: We reviewed up-to-date surveillance reports published by the National Institute of Infectious Diseases and Tokyo Metropolitan Infectious Disease Surveillance Center. RESULTS: Communicable disease risks for vaccine-preventable illnesses such as measles and rubella, as well as food and waterborne diseases represent the most likely risks. The risk of acquiring vector-borne diseases is considered low in Japan. On the other hand, however, heat-related illness represents a potential risk, as Tokyo 2020 is scheduled during the hottest season in Japan, with temperatures generally expected to exceed 30 °C. CONCLUSION: Maintaining an up-to-date routine vaccination schedule is highly recommended for visitors attending the Tokyo 2020 and appropriate hygiene measures for food and waterborne diseases as well as health promotion for heat-related illness. It may also be useful to increase the number of multilingual triage clinicians whom can be placed within emergency departments during the Tokyo 2020 to provide first contact services and coordination of emergency care among non-Japanese speaking visitors to Tokyo.

Ensuring the Right to Rest: City Ordinances and Access to Rest Breaks for Workers in the Construction Industry.

OBJECTIVE: The aim of this study was to evaluate the effectiveness of city Rest Break Ordinance (RBO) policies in expanding access to rest at work. METHODS: We use data from surveys of construction workers in Austin and Dallas, Texas, in 2009, 2012, and 2015 (n = 557) to calculate the odds of receiving a rest break in pre- versus post-RBO Austin and in post-RBO Austin versus pre-RBO Dallas, controlling for demographic and employment characteristics. RESULTS: Construction workers were 35% more likely to report receiving a rest break in Austin post-RBO and 16% less likely in Dallas without a RBO as compared to Austin with a RBO. CONCLUSION: The increased likelihood of receiving rest breaks at work in a RBO city suggests that, in the absence of enforceable national standards, city-level RBOs can be an important first step to effective prevention of heat-related illnesses (HRIs) and heat-related fatalities at work.

Air velocity influences thermoregulation and endurance exercise capacity in the heat.

This study examined the effects of variations in air velocity on time to exhaustion and thermoregulatory and perceptual responses to exercise in a hot environment. Eight male volunteers completed stationary cycle exercise trials at 70% peak oxygen uptake until exhaustion in an environmental chamber maintained at 30 °C and 50% relative humidity. Four air velocity conditions, 30, 20, 10, and 0 km/h, were tested, and the headwind was directed at the frontal aspect of the subject by 2 industrial fans, with blade diameters of 1 m and 0.5 m, set in series and positioned 3 m from the subject's chest. Mean ± SD time to exhaustion was 90 ± 17, 73 ± 16, 58 ± 13, and 41 ± 10 min in 30-, 20-, 10-, and 0-km/h trials, respectively, and was different between all trials (P < 0.05). There were progressive elevations in the rate of core temperature rise, mean skin temperature, and perceived thermal sensation as airflow decreases (P < 0.05). Core temperature, heart rate, cutaneous vascular conductance, and perceived exertion were higher and evaporative heat loss was lower without airflow than at any given airflow (P < 0.05). Dry heat loss and plasma volume were similar between trials (P > 0.05). The present study demonstrated a progressive reduction in time to exhaustion as air velocity decreases. This response is associated with a faster rate of core temperature rise and a higher skin temperature and perceived thermal stress with decreasing airflow. Moreover, airflow greater than 10 km/h (2.8 m/s) might contribute to enhancing endurance exercise capacity and reducing thermoregulatory, cardiovascular, and perceptual strain during exercise in a hot environment.

Effects of caffeine on endurance capacity and psychological state in young females and males exercising in the heat.

Acute caffeine ingestion is considered effective in improving endurance capacity and psychological state. However, current knowledge is based on the findings of studies that have been conducted on male subjects mainly in temperate environmental conditions, but some physiological and psychological effects of caffeine differ between the sexes. The purpose of this study was to compare the physical performance and psychological effects of caffeine in young women and men exercising in the heat. Thirteen male and 10 female students completed 2 constant-load walks (60% of thermoneutral peak oxygen consumption on a treadmill until volitional exhaustion) in a hot-dry environment (air temperature, 42 °C; relative humidity, 20%) after caffeine (6 mg·kg-1) and placebo (wheat flour) ingestion in a double-blind, randomly assigned, crossover manner. Caffeine, compared with placebo, induced greater increases (p < 0.05) in heart rate (HR) and blood lactate concentrations in both males and females but had no impact on rectal or skin temperatures or on walking time to exhaustion in subjects of either gender. Caffeine decreased (p < 0.05) ratings of perceived exertion and fatigue in males, but not in females. In females, but not in males, a stronger belief that they had been administered caffeine was associated with a shorter time to exhaustion. In conclusion, acute caffeine ingestion increases HR and blood lactate levels during exercise in the heat, but it has no impact on thermoregulation or endurance capacity in either gender. Under exercise-heat stress, caffeine reduces ratings of perceived exertion and fatigue in males but not in females.

Cooling Methods to Prevent Heat-Related Illness in the Workplace.

The common practice of workers resting in the shade to dissipate body heat can be complemented by ingestion of crushed ice or immersion in temperate water to rapidly lower core body temperature.

Risk and preventive factors for heat illness in radiation decontamination workers after the Fukushima Daiichi Nuclear Power Plant accident.

OBJECTIVES: The aim of this study was to reveal factors related to heat illness in radiation decontamination workers and determine effective preventive measures. METHODS: A self-administered questionnaire was sent to 1,505 radiation decontamination workers. The questionnaire included age, sex, duration of decontamination work, previous occupation, education provided by employers regarding heat illness, preventive action against heat illness, and subjective symptoms of heat illness during work. We included 528 men, who replied and answered all questions, in the statistical analysis. Subjective symptoms of heat illness were categorized as "no symptoms", "Grade I" and "Grade II" according to severity. A multiple linear regression model was used to determine the factors associated with the severity of heat illness. RESULTS: The mean age of the subjects was 47.6 years old (standard deviation: 13.4). Of the 528 workers, 316 (59.8%) experienced heat illness symptoms (213 at Grade I and 103 at Grade II). The results of the stepwise selection revealed that age, outdoor manual labor, adequate sleep, use of a cool vest, and salt intake were selected as preventive factors, whereas living in a company dormitory or temporary housing, wearing light clothing, and consuming breakfast were selected as risk factors for heat illness. CONCLUSIONS: Both working conditions and living environment are associated with heat illness in radiation decontamination workers. Type of housing and sleep are also strongly related to heat illness during work. Employers should consider not only the working conditions of the employee but also the employee's daily living conditions, in order to prevent heat illness.

Socio-demographic vulnerability to heatwave impacts in Brisbane, Australia: a time series analysis.

OBJECTIVE: Examining the association between socioeconomic disadvantage and heat-related emergency department (ED) visits during heatwave periods in Brisbane, 2000-2008. METHODS: Data from 10 public EDs were analysed using a generalised additive model for disease categories, age groups and gender. RESULTS: Cumulative relative risks (RR) for non-external causes other than cardiovascular and respiratory diseases were 1.11 and 1.05 in most and least disadvantaged areas, respectively. The pattern persisted on lags 0-2. Elevated risks were observed for all age groups above 15 years in all areas. However, with RRs of 1.19-1.28, the 65-74 years age group in more disadvantaged areas stood out, compared with RR=1.08 in less disadvantaged areas. This pattern was observed on lag 0 but did not persist. The RRs for male presentations were 1.10 and 1.04 in most and less disadvantaged areas; for females, RR was 1.04 in less disadvantaged areas. This pattern persisted across lags 0-2. CONCLUSIONS: Heat-related ED visits increased during heatwaves. However, due to overlapping confidence intervals, variations across socioeconomic areas should be interpreted cautiously. IMPLICATIONS: ED data may be utilised for monitoring heat-related health impacts, particularly on the first day of heatwaves, to facilitate prompt interventions and targeted resource allocation.

The impact of heatwaves on emergency department visits in Brisbane, Australia: a time series study.

INTRODUCTION: The acute health effects of heatwaves in a subtropical climate and their impact on emergency departments (ED) are not well known. The purpose of this study is to examine overt heat-related presentations to EDs associated with heatwaves in Brisbane. METHODS: Data were obtained for the summer seasons (December to February) from 2000-2012. Heatwave events were defined as two or more successive days with daily maximum temperature ≥34°C (HWD1) or ≥37°C (HWD2). Poisson generalised additive model was used to assess the effect of heatwaves on heat-related visits (International Classification of Diseases (ICD) 10 codes T67 and X30; ICD 9 codes 992 and E900.0). RESULTS: Overall, 628 cases presented for heat-related illnesses. The presentations significantly increased on heatwave days based on HWD1 (relative risk (RR) = 4.9, 95% confidence interval (CI): 3.8, 6.3) and HWD2 (RR = 18.5, 95% CI: 12.0, 28.4). The RRs in different age groups ranged between 3-9.2 (HWD1) and 7.5-37.5 (HWD2). High acuity visits significantly increased based on HWD1 (RR = 4.7, 95% CI: 2.3, 9.6) and HWD2 (RR = 81.7, 95% CI: 21.5, 310.0). Average length of stay in ED significantly increased by >1 hour (HWD1) and >2 hours (HWD2). CONCLUSIONS: Heatwaves significantly increase ED visits and workload even in a subtropical climate. The degree of impact is directly related to the extent of temperature increases and varies by socio-demographic characteristics of the patients. Heatwave action plans should be tailored according to the population needs and level of vulnerability. EDs should have plans to increase their surge capacity during heatwaves.

A randomized controlled trial of aspirin and exertional heat stress activation of platelets in firefighters during exertion in thermal protective clothing.

PURPOSE: Platelet aggregation is enhanced in firefighters following short bouts of work in thermal protective clothing (TPC). We sought to determine if aspirin therapy before and/or following exertion in TPC prevents platelet activation. METHODS: In a double-blind, placebo-controlled study, 102 firefighters were randomized to receive daily therapy (81 mg aspirin or placebo) for 14 days before and a single dose (325 mg aspirin or placebo) following exercise in TPC resulting in four potential assignments: aspirin before and after exercise (AA), placebo before and after exercise (PP), aspirin before and placebo after exercise (AP), and placebo before and aspirin after exercise (PA). Platelet closure time (PCT) was measured with a platelet function analyzer before the 2-week treatment, after the 2 week treatment period, immediately after exercise, and 30, 60, and 90 minutes later. RESULTS: Baseline PCT did not differ between groups. PCT changed over time in all four groups (p < 0.001) rising to a median of >300 seconds [IQR 99, 300] in AA and >300 [92, 300] in AP prior to exercise. Following exercise, median PCT decreased to in all groups. Median PCT returned to >300 seconds 30 minutes later in AA and AP and rose to 300 seconds in PA 60 minutes after exercise. CONCLUSIONS: Daily aspirin therapy blunts platelet activation during exertional heat stress and single-dose aspirin therapy following exertional heat stress reduces platelet activation within 60 minutes.

Effectiveness of exercise-heat acclimation for preventing heat illness in the workplace.

The incidence of heat-related illness in the workplace is linked to whether or not workers have acclimated to a hot environment. Heat acclimation improves endurance work performance in the heat and thermal comfort at a given work rate. These improvements are achieved by increased sweating and skin blood flow responses, better fluid balance and cardiovascular stability. As a practical means of acclimatizing the body to heat stress, daily aerobic exercise training is recommended since thermoregulatory capacity and blood volume increase with physical fitness. In workers wearing personal protective suits in hot environments, however, little psychophysiological benefit is received from short-term exercise training and/or heat acclimation because of the ineffectiveness of sweating for heat dissipation and the aggravation of thermal discomfort with the accumulation of sweat within the suit. For a manual laborer who works under uncompensable heat stress, better management of the work rate, the work environment and health is required.

Aclimatación al ejercicio físico en situaciones de estrés térmico / Acclimatisation to physical exercise to thermal stress

Homeotermia y actividad física en situaciones de estrés térmico. El ser humano es homeotérmico. Podemos regular nuestra temperatura corporal dentro de unos estrechos márgenes (34ºC-45ºC). Los sistemas de homeostasis pueden verse seriamente alterados en situaciones térmicas extremas. Factores que influencian la termorregulación durante la actividad física en situaciones de estréstérmico. Son fundamentalmente tres: estado de aclimatación, forma física e hidratación del individuo. - Aclimatación: Conjunto de adaptaciones que permiten mejorar la tolerancia al estrés térmico. Calor. El cuerpo induce cambios en la cantidad y calidad del sudor adaptándole a trabajar en ambiente caluroso, almacenando menos calor en el núcleo interno. Las adaptaciones cardiovasculares y termorreguladoras suceden en los primeros días de exposición al calor. Requieren exposiciones repetidas al calor, entrenando con una intensidad de esfuerzo de, al menos, el 50% del consumo máximo de oxígeno (VO2max). Frío. La adaptación al frío en mucho menos compleja, consistiendo fundamentalmente en una adecuada hidratación, entrenamiento y dieta equilibrada hipercalórica. - Estado de forma física: El estado de forma física (VO2max) no es un marcador decisivo para la tolerancia al calor pero es un factor adicional de tolerancia térmica si el atleta se aclimata entrenando a temperaturas altas. - Estado de hidratación Calor. Los efectos negativos de la deshidratación se observan tanto si el sujeto se deshidrata durante el ejercicio prolongado, como si comienza el esfuerzo bajo condiciones de hipohidratación. Frío. Induce la diuresis al aumentar el volumen sanguíneo central. Una vestimenta inadecuada puede conducir a un aumento de las pérdidas por sudor superiores a 2L/h. Conclusiones: A pesar de que los individuos pueden adaptar la actividad física al estrés térmico gracias a la aclimatación, en el momento actual "no existe evidencia que demuestre que es posible adaptarse a la hipohidratación", es más, la hipohidratación limita los beneficios de la aclimatación (AU)

Homeothermy and physical activity in extreme situations.Humans are homeothermic; we are able to regulate our body temperature although within very narrow margins, (34 º C-45 º C). Homeostasis systems are intensely altered in extreme thermal conditions. Factors influencing thermoregulation during physical exercise in extreme situations. State of acclimatisation, fitness and hydration of the person.- Acclimatisation: Set of adaptations that allow a person to tolerate greater stress due to environmental conditions Heat: Body induces changes in the quantity and quality of sweating and blood flow, adapting the body to work in hot weather, storing less internal heat. Cardiovascular and thermoregulatory adaptations occur during the first days of heat exposure. Requires repeated exposure to heat, training at an exercise intensity of at least 50% of maximal oxygen consumption (VO2max). Cold. Adaptation to cold is less complex. Adequate clothing, training and a high calorie balanced diet are required.- State of fitness The physical fitness (VO-2max) is not a decisive marker for heat tolerance but it is an additional factor of thermal tolerance, if the athlete becomes acclimated by training at extremes temperatures.- State of hydration Heat: The negative effects of the dehydrationare observed both when subjects are dehydrated during prolonged exercise, as they begin the exercise under hypo hydration conditions. Cold. It induces diuresis through an increased central blood volume. Inappropriate clothes induce fluid loss due to sweat of up to 2 L / h. Conclusions: Although it is true that people can adapt to physical activity and heat stress by acclimatization "there is no evidence to show that it is possible to adapt to hypohydration". In fact, hypohydration limits the benefits of acclimatization (AU)

Keeping your cool: possible mechanisms for enhanced exercise performance in the heat with internal cooling methods.

Exercising in hot environments results in a rise in core body temperature; an effect associated with impaired performance over a variety of exercise modes and durations. Precooling has become a popular strategy to combat this impairment, as evidence has shown it to be an effective method for lowering pre-exercise core temperature, increasing heat storage capacity and improving exercise performance in the heat. To date, the majority of precooling manoeuvres have been achieved via external means, such as cold water immersion and the application of cooling garments. However, these methods have been criticized for their lack of practicality for use in major sporting competitions. Recent evidence has shown that internal or endogenous cooling methods, such as drinking cold fluids or ice slurries, are able to lower core temperature and enhance endurance performance in the heat. These methods may be more advantageous than current forms of precooling, as ingesting cold fluids or ice slurries can be easily implemented in the field and provide the additional benefit of hydrating athletes. While the precise mechanisms responsible for these performance enhancements are yet to be fully explained, the effect of ice ingestion on brain temperature, internal thermoreception and sensory responses may be involved. This article addresses the evidence supporting the use of endogenous cooling methods for improving endurance performance in the heat, as well as discussing the potential mechanisms behind the improvements observed and providing practical recommendations to optimize their success.