Heat illness during working and preventive considerations from body fluid homeostasis

Changes in thermal comfort, core temperature, and body weight during simulated parcel home-delivery in summer and winter

Our aim was to determine differences in thermal comfort during simulated one-day parcel home delivery between summer and winter. Six young healthy males performed experiments in summer (up to 31°C) and winter (up to 8°C). After baseline measurement in a chamber, subjects drove a truck to a prespecified location for outside measurements. They performed 4 sets of 100-m walk with carrying 5-kg plate during the first 50-m walk at 100 m/min, separated by 7-min driving in each of the morning and the afternoon. Subjects could ingest water ad libitum in outside and set the cockpit temperature by themselves during driving. Thermal sensation and comfort were recorded using a subjective scale at the first and the last sets of each morning and afternoon session, while esophageal temperature (T_es) was monitored (thermocouples). Body weight was measured before and the end of experiment. We found that 1) whole-body comfort decreased in summer and the decrease was greater than winter with higher T_es and 2) changes in body weight were 0.7 and 0.3 kg through whole day in summer and winter, respectively. In summary, thermal comfort during working worsened in summer, possibly related with higher core temperature and greater decrease in body weight.

Protective measures of patients with cardiovascular diseases from exposure to heat waves: medicated and non-medicated

In conditions of climate warming with an increase in heat waves associated with an increase in cardiovascular morbidity and mortality, the particular interest is the effect of cardiovascular drugs on adaptation to high temperatures. The review reflects the results of European and domestic studies on the safety of therapy during long and short heat waves. Recommendations for the correction of therapy during this period are given. Self-control of blood pressure (SCAD) is a mandatory component of the therapy of arterial hypertension during heat waves. With the development of clinically significant hypotension, a reduction in the dose of antihypertensive drugs is necessary. It is recommended to start with a dose reduction and/or withdrawal of diuretics and nitrates. Not recommended the complete abolition of antihypertensive therapy because of the risk of hypertensive crises, characteristic of abnormal heat, as well as due to the increase in blood pressure when the weather changes and the temperature drops. With increasing blood pressure during heat waves, it is recommended to give preference to calcium channel antagonists, angiotensin converting enzyme inhibitors (ACE inhibitors) and selective beta-blockers. It is necessary to inform patients about the additional protective effect of statins in order to increase adherence to therapy. Patients taking diuretics require individual daily monitoring of fluid intake and body weight. An overview of recommendations on sanogenic behavior during heat waves is given. Details are considered rules for the use of air conditioning, methods of diagnosis of dehydration and drinking mode Keywords: heat waves, cardiovascular complications, preventive measures.

Interactions between body fluid homeostasis and thermoregulation in humans

Humans are unique in their ability to control body temperature with a large amount of skin blood flow and sweat rate while exercising in an upright position. However, cutaneous vasodilation in the body reduces total peripheral resistance and blood pooling in cutaneous veins decreases venous return to the heart and cardiac filling pressure. In addition, hypovolemia by sweating accelerates the reduction in cardiac filling pressure. These may threaten the maintenance of blood pressure if they are not compensated for. To prevent this, cutaneous vasodilation and sweat rate are suppressed by baroreflexes or hyperosmolality with dehydration. These mechanisms suppress heat dissipation, accelerate the increase in body temperature, and sometimes cause heat stroke. As a countermeasure to prevent this, we have recommended glucose electrolyte solutions but recently found that aerobic training with carbohydrate + whey protein supplementation markedly improves heat dissipation mechanisms by plasma volume expansion. In this article, we will discuss the importance of improving body fluid homeostasis for thermoregulation under heat stress in humans and the strategy to attain this.

Heat and PAHs Emissions in Indoor Kitchen Air and Its Impact on Kidney Dysfunctions among Kitchen Workers in Lucknow, North India

Indoor air quality and heat exposure have become an important occupational health and safety concern in several workplaces including kitchens of hotels. This study investigated the heat, particulate matter (PM), total volatile organic compounds (TVOCs) and polycyclic aromatic hydrocarbons (PAHs) emissions in indoor air of commercial kitchen and its association with kidney dysfunctions among kitchen workers. A cross sectional study was conducted on 94 kitchen workers employed at commercial kitchen in Lucknow city, North India. A questionnaire-based survey was conducted to collect the personal and occupational history of the kitchen workers. The urine analysis for specific gravity and microalbuminuria was conducted among the study subjects. Indoor air temperature, humidity, wet/ dry bulb temperature and humidex heat stress was monitored during cooking activities at the kitchen. Particulate matter (PM) for 1 and 2.5 microns were monitored in kitchen during working hours using Hazdust. PAH_S in indoor air was analysed using UHPLC. Urinary hydroxy-PAHs in kitchen workers were measured using GC/MS-MS. Higher indoor air temperature, relative humidity, PM₁ and PM_2.5 (p<0.001) was observed in the kitchen due to cooking process. Indoor air PAHs identified are Napthalene, fluorine, acenaphthene, phenanthrene, pyrene, chrysene and indeno [1,2,3-cd) pyrene. Concentrations of all PAHs identified in kitchen were above the permissible OSHA norms for indoor air. Specific gravity of urine was significantly higher among the kitchen workers (p<0.001) as compared to the control group. Also, the prevalence of microalbuminuria was higher (p<0.001) among kitchen workers. Urinary PAH metabolites detected among kitchen workers were 1-NAP, 9-HF, 3-HF, 9-PHN and 1-OHP. Continuous heat exposure in kitchens due to cooking can alter kidney functions viz., high specific gravity of urine in kitchen workers. Exposure to PM, VOCs and PAHs in indoor air and presence of urinary PAHs metabolites may lead to inflammation, which can cause microalbuminuria in kitchen workers, as observed in the present study.

Subjective symptoms of female workers sorting goods in summer

Subjective musculoskeletal symptoms are more frequently complained about in cold store work and in related conditions than those experienced in normal temperature work. This cross sectional study was undertaken to evaluate the effects of indoor cooling and cold storage goods on the prevalence of subjective symptoms in summer. Female workers sorting cold storage goods (exposed group) were the main subjects of this study (n=47). We also included a group of female workers engaged sorting dry goods as the unexposed to cold group (n=86). Work load for the two groups were estimated according to the recommended criteria. A self-administered questionnaire covering age, occupational career, smoking, alcohol drinking and physical exercise, present or past history of diseases, individual protective measures against cold or heat, and subjective symptoms (60 items) was used. The air temperature of the site at the start of working time for the workers sorting cold storage goods was 22.2℃ which was significantly lower than those measured for the other two work places (25.4℃ and 25.4℃) of the unexposed to cold group. Environmental temperatures at the foot level at the sorting workshop of cold storage goods and dry goods were ca.16℃ and 26℃ all day, respectively. The surface temperatures of cold storage goods were between -2.8℃ and 9.4℃. The surface temperature of dry goods was 26.5℃. Among the working characteristic items, only daily working hours in the exposed group (5.6 ± 0.6 h) were significantly longer than those in the unexposed to cold group (4.6 ± 0.9 h) (p<0.01). The prevalence rates of finger cold sensation, stiffness in the fingers, pain in the wrist, pain in the elbow, back dullness, back pain, low-back cold sensation, foot cold sensation and pain in the foot in the exposed group were significantly higher than those in the unexposed to cold group (p<0.05 or p<0.01). Pain in the fingers, numbness in the fingers, pain in the foot and foot numbness due to the cold in the exposed group were significantly higher than those in the unexposed to cold group (p<0.05 or p<0.01). These results suggest that indoor cooling and/or job activities related to cold storage goods could, to some extent, affect peripheral circulatory disturbances; and it could be regarded as a factor related to musculoskeletal symptoms among the exposed workers.

Evaluation of subjective thermal strain in different kitchen working environments using subjective judgment scales

To elucidate the subjective thermal strain of workers in kitchen working environments, we performed a cross-sectional study involving 991 workers in 126 kitchen facilities in Japan, using a self-reporting questionnaire survey and subjective judgment scales (SJS). The ambient temperature, mean radiant temperature (MRT), and wet-bulb globe temperature (WBGT) index were measured in 10 kitchen facilities of the 126 kitchens. The association of SJS with the types of kitchen was estimated by multiple logistic regression models. Of the 991 kitchen workers, 809 (81%) responded to the questionnaire survey. Compared with the electric kitchens, the proportion of workers who perceived the room temperature as hot to very hot was significantly higher, and the ambient temperature, MRT, and WBGT were significantly higher in the gas kitchens. Compared with the electric kitchens, workers in gas kitchens had a more than fivefold (males) and tenfold (females) higher SJS adjusted for confounding factors (male odds ratio (OR), 5.13; 95% confidence interval (CI), 1.65-15.9; and female OR, 10.9; 95%CI, 3.89-30.5). Although SJS was affected by some confounding factors, our results suggest that workers in gas kitchens might be exposed to a higher heat strains than those in electric kitchens.