Objectives To examine the thermoregulatory and fluid‐electrolyte responses of firefighters ingesting ice slurry and carbohydrate–electrolyte solutions before and after firefighting operations. Methods Twelve volunteer firefighters put on fireproof clothing and ingested 5 g/kg of beverage in an anteroom at 25°C and 50% relative humidity (RH; pre‐ingestion), and then performed 30 minutes of exercise on a cycle ergometer (at 125 W for 10 minutes and then 75 W for 20 minutes) in a room at 35℃ and 50% RH. The participants then returned to the anteroom, removed their fireproof clothing, ingested 20 g/kg of beverage (post‐ingestion), and rested for 90 minutes. Three combinations of pre‐ingestion and post‐ingestion beverages were provided: a 25℃ carbohydrate–electrolyte solution for both (CH condition); 25℃ water for both (W condition); and a −1.7℃ ice slurry pre‐exercise and 25℃ carbohydrate–electrolyte solution post‐exercise (ICE condition). Results The elevation of body temperature during exercise was lower in the ICE condition than in the other conditions. The sweat volume during exercise was lower in the ICE condition than in the other conditions. The serum sodium concentration and serum osmolality were lower in the W condition than in the CH condition. Conclusions The ingestion of ice slurry while firefighters were wearing fireproof clothing before exercise suppressed the elevation of body temperature during exercise. Moreover, the ingestion of carbohydrate–electrolyte solution by firefighters after exercise was useful for recovery from dehydration.
ObjectivesTo evaluate the efficacy of water‐cooled clothing that continuously cools restricted body areas to suppress body temperature increase as an anti‐heatstroke measure for workers in hot environments that exceed body temperature.MethodsTen healthy men were placed in Room A (air temperature: 25°C, relative humidity: 50%) for 15 min. They were then transferred to Room B (air temperature: 40°C, relative humidity: 50%), where they rested for 10 min, then put on cooling clothing, and again rested for 15 min (the control group rested for 25 min). They then performed intense ergometer exercise for 40 min at 40% maximal oxygen consumption after which they rested for 10 min. The three trial conditions were CON (long‐sleeved summer work clothes), VEST (cooling vest), and P‐VEST (partial cooling vest). In VEST and P‐VEST, water‐cooled clothing continuously recirculated with 10°C water was used to cool the upper body. In P‐VEST, only the neck, axillae, and heart areas were in contact with the cooled clothing. The measured indices were the rectal, esophageal, and external auditory canal temperatures; heart rate; estimated sweat volume; and subjective evaluations.ResultsCompared with the CON condition, the rectal, esophageal, and external auditory canal temperatures and the heart rate were significantly lower and the subjective indices were decreased in the VEST and P‐VEST conditions.ConclusionsPartial cooling showed a body cooling effect similar to that of whole upper body cooling. Partial body cooling promoted the heat dissipation, suggesting that partial cooling is efficient for maintaining body cooling in hot environments.
IntroductionPrimary causes of heat-related illness (HRI) at work are:extreme heat and humidity,heavy work load,continuous exertion and infrequent rest,clothes with poor vapor–permeability, andpersonal health condition.Empirical research has not been performed to investigate the effect of underlying health problems to HRI.MethodsA case-control study was performed by asking occupational health staffs to report all HRI cases occurred at their workplaces in 2015 and 2016. One co-worker control of the same gender at the closest in age was also reported for each case. Target population included:26 large manufacturing factories,15 major construction companies,all traffic guard companies in Japan, anda fire stations in Kitakyushu city.Their results of the periodic health examination were collected to evaluate the underlying health problems of obesity (BMI >25), impaired glucose tolerance, IGT (HbA1c≥6.5%, fast blood sugar ≥126 mg/dL, and/or casual blood sugar ≥200 mg/dL), high blood pressure, HBP (≥140/90 mmHg), and dyslipidemia (LDL-C ≥140 mg/dL, HDL-C <40 mg/dL, or TG ≥150 mg/dL). Data were statistically compared between the case and the control using JMP Pro 13.ResultsOverall incidence rate of HRI at the examined workplaces was 0.065% (114 cases/1 76 094 person-year). A total of 102 pairs (n=204) could be compared. Cases showed higher BMI (p=0.046) and visceral circumference (p=0.045). Cases and controls included 12 and 2 persons with IGT, respectively (p=0.005). Multiple logistic regression analysis revealed increase of HbA1c elevated the risk of developing HRI (OR 16.76 [95% CI: 2.44 to 165.5], p=0.0014), whereas LDL-cholesterol showed protective effect (OR 0.97 [0.95–0.99], p<0.001).ConclusionSignificantly elevated risk of developing heat-related illness was observed among workers with IGT. Impaired endothelium-dependent vasodilatation among workers with IGT may decrease heat dissipation by conduction, convection, radiation, and sweat evaporation and may pose a risk to develop HRI.
focused on tank trucker loading operations, which were made most of the time by the truck drivers themselves, exposing the drivers to petroleum-derived fuel compounds. This kind of activity should be done by the operators of the distribution terminal, not by the truck drivers. These drivers were submitted to activities of an ambiguous nature, without qualification, adequate training, and supervision. The goal of the intervention was to change the organisation of the work in the distribution terminal as a method of reducing respiratory exposure of the truck drivers to occupational health hazards. Methods It is a prospective descriptive case study. The period covered refers to the beginning of the inspection in the year of 2012 up to 2017. It was analysed documents that the distribution terminal has presented to labours inspection. Result The organisation of the work at the distribution terminal changed radically. The truck drivers are not doing any operation at the terminal anymore. The distribution terminal hired new operators, modified the distribution process and yet built an occupational medical centre for their workers and for the truck drivers as a preventive measure of health. Conclusion This case showed that is possible for Brazilians Petroleum-derived fuel distribution companies to change their work organisation and improve their environment minimising the exposure of truck drivers to occupational health hazards such as benzene.
IntroductionIt is known that heat stroke is likely to occur when workers are not acclimatised to heat. The purpose of this study is to clarify if the physiological responses of heat acclimatisation are different by the seasonal difference of the temperature in living environment.MethodsFour healthy males in twenties repeated a 20 minutes-exercise on an ergometer at 40% VO2max for three times in three different thermal environments in the artificial climate room controlled at 28°C, then elevated to 34°C and finally to 40°C where relative humidity was fixed at 50%. Each exercise was followed by 20 minutes-rest period kept seated in the adjunct room at 24°C. They were asked to exercise consecutively for five days. This series of intervention was repeated during summer and winter seasons. We continuously measured their auditory canal temperature (t ac) and heart rate (HR). We also examined their sweat Na+ and K+ concentration and estimated their sweat volume from the body weight loss.ResultThe observed t ac and HR at the end of the exercise were generally higher in winter compared to summer. The sweat volume gradually increased for five days and the volume during the first exercise period at 28°C was larger in summer; however, the amount of increase was larger in winter. The sweat Na+ concentration positively correlated with sweat volume and we observed smaller elevation of Na+ concentration along with the increase of sweat volume in summer.DiscussionThe lower t ac and HR, earlier sweating, and smaller elevation of Na+ concentration during heat acclimatisation in summer seem to be caused by the different thermal condition of living environment
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