Objectives - To examine the incidence, clinical state, personal risk factors, haematology and biochemistry of heat exhaustion cases occurring at a deep underground metalliferous mine. To describe the underground and surface thermal conditions associated with the occurrence of heat exhaustion cases.Methods - A one-year prospective case-series of acute heat exhaustion cases was undertaken at a deep underground metalliferous mine in tropical and Australia. A case-control study of body mass index (BMI) and maximal oxygen uptake (VO(subscript)2max) in heat exhaustion was also undertaken. A history was obtained using a structured questionnaire. Pulse rate, blood pressure, tympanic temperature and urine specific gravity were measured before treatment. Venous blood was analysed for haematological and biochemical parameters, during the acute presentation and after recovery. BMI and VO(subscript)2max were measured after recovery and in a group of controls. Psychrometric wet bulb temperature, dry bulb temperature and air velocity were measured at the underground sites where heat exhaustion had occurred. Air cooling power and psychrometric wet bulb globe temperatures were derived. Surface 24-hour mean wet bulb and dry bulb temperatures were recorded. Surface 24-hour mean wet bulb globe temperatures were derived.Results - 106 cases were studied in the case series. The incidence of heat exhaustion during the year was 43.0 cases per million man-hours. In February it was 147 cases per million man-hours. The incidence rate ratio for mines operating below 1200m compared to those operating above 1200m was 3.17. Mean estimated fluid intake was 0.64 litres/hour (SD 0.29, Range 0.08-1.50).The following were raised on acute presentation compared to recovery (P value, % of acute cases above the normal clinical range): neutrophils (P<0.001, 36%), anion gap (P<0.001, 63%), urea (P<0.001, ++ / 21%), creatinine (P<0.001, 30%), glucose (P<0.001, 15%), serum osmolality (P=0.030, 71%), creatine kinase (P=0.002, 45%), aspartate transaminase (P<0.001, 14%), lactate dehydrogenase (P<0.001, 9.5%), and ferritin (P<0.001, 26%). The following were depressed on acute presentation compared to recovery (P value, % of acute cases below the normal clinical range): eosinophils (P=0.003, 3 8%) and bicarbonate (P=0.0 11, 32%). Urea and creatinine were significantly raised in miners with heat cramps compared to miners without this symptom (P<0.001), while there was no significant difference in sodium concentration (P=0.384).Mean psychrometric wet bulb temperature was 29.0 degrees celsius (SD 2.2, Range 21.0-34.0). Mean dry bulb temperature was 37.4 degrees celsius (SD 2.4, Range 31.0-43.0). Mean air velocity was 0.54 m/s (SD 0.57, Range 0.00-4.00). Mean air cooling power was 148 W/m(subscript)2 (SD 49, Range 33-290). Mean psychrometric wet bulb globe temperature was 31.5 degrees celsius (SD 2.0, Range 25.2-35.3). Few cases (<5%) occurred at a psychrometric wet bulb temperature <25.0'C, dry bulb temperature <33.8'C, air velocity >1.56 m/s, air cooling power >248 W/m(subscript)2, or psychrometric wet bulb globe temperature <28.5 degrees Celsius.The three surface temperature variables were significantly higher on those days on which heat exhaustion occurred compared to those days on which it did not occur (P<0.001). The relative risk of heat exhaustion on days when the surface 24-hour mean wet bulb globe temperature was in the range 26.0-28.0 degrees celsius was 4.82 (95% CI 2.12-10.96).65 cases of heat exhaustion and 119 controls were studied in the case-control study. Heat exhaustion cases had a significantly higher BMI than controls (P=0.006). The odds ratios increased with BMI. For a BMI of 32.00-36.99, compared to a BMI of less than 27.00 the odds ratio was 3.63 (95% ++ / confidence interval 1.42-9.36). V0(subscript)2max was not significantly lower in cases than controls. The odds ratios for heat exhaustion increased with decreasing VO(subscript)2max, but not significantly. The sample size provided 80% power of detecting an odds ratio of 2.5 or greater.Conclusion - Heat exhaustion in underground miners is associated with hypohydration, neutrophil leukocytosis, eosinopenia, metabolic acidosis, increased glucose and ferritin, and a mild rise in CK, AST and LD. Heat cramps are associated with hypohydration but not hyponatraemia. The incidence of heat exhaustion increases during summer and at depth. An increased fluid intake is required. Heat exhaustion would be unlikely to occur if ventilation and refrigeration achieved air cooling power >250W/m2 at all underground work sites. Surface temperature data could be used at this mine to warn miners about the risk of heat exhaustion. Deep underground miners should be advised to maintain a BMI of 24-27.

Thesis (M.Sc.(Hons.))--University of Wollongong, 2006. / Typescript. Includes bibliographical references.

Due to inadequate training and an undeveloped ability to recognize dangerous scenarios, youth workers are exposed to many dangers in the agriculture and lawn care industries. With the abundance of new technologies available on the market, a project was devised to prevent youth from heat exhaustion and equipment run overs by employing sensor based technologies. Using aural temperature measurement techniques involving a thermistor and thermopile, an accurate estimation of core body temperature can be made. The measurements performed by the devices are recorded and transmitted wirelessly over a ZigBee network using XBee radiofrequency modules. Utilizing the properties of radiofrequency transmission, the Received Signal Strength Indication (RSSI) is used to approximate the distance between devices. With accuracy comparable to GPS methods and no necessity for line of sight to sky, RSSI supplies a more than adequate estimate for proximity distance. The temperature and RSSI values are then sent to a coordinating modem where the data is displayed for the supervisor. After testing and calibrating the device, it was found that these methods are effective for the monitoring of core body temperature and proximity of workers. The temperature sensor was able to measure temperatures with less than 0.25% error and the proximity sensor was able to estimate distance within 1.25 meters at close range. / Master of Science

Children are considered a vulnerable population in society. While thermoregulation in children is similar to that of an adult, children are vulnerable to heat-related illness. Student athletes have been found to be particularly vulnerable to heat-related illness for numerous reasons, including intense outdoor play. Football players are perhaps the most at-risk population of student athletes due to the intense physical requirements, outdoor practice during the hottest months of the year, and the extensive protective equipment required. By conducting a literature review on the subject of pediatric heat illness, the purpose of this thesis is to explore evidenced based research and guidelines regarding heat-related illness prevention. This review of literature was conducted through the utilization of the University of Central Florida's online databases using the EBSCOhost platform of: CINAHL Plus with Full Text, Cochrane Database of Systematic Reviews, ERIC, Health Source: Nursing/Academic Edition, MEDLINE, PsycINFO and SPORTDiscus. This thesis is unique because it does not focus on an individual sport; rather, it focuses on pediatric athletes from various disciplines. The prevalence, pathophysiology, prevention, and treatment of heat-related injuries are complex phenomena requiring the attention of law makers, athletic associations, school officials, coaches, athletic trainers, parents, and students.

Heat stress illnesses, including heat stroke and heat exhaustion, represent a serious, persistent, and growing public health threat to military and civilian populations. Global climate change, due primarily to increased greenhouse gas concentrations in the atmosphere, has resulted in measured increases in temperature and humidity. Climate models project warming trends to continue in the future with very high confidence, resulting in more dangerous mean and extreme heat conditions. The associations between environmental heat indicators and observed adverse health outcomes have been increasingly studied for mortality endpoints and among elderly populations. This dissertation aimed to expand this investigation to heat illness morbidity outcomes among active-duty military servicemembers while assessing a range of heat indices. This is an assumed healthy, working-age population that is regularly exposed to outdoor heat in combination with high levels of exertion. Comparable civilian populations, in some respects, include athletes and outdoor laborers such as construction workers or farmers. In Chapter 2, we assessed annual rates of ambulatory encounters, hospitalizations, and reportable events among active-duty soldiers at ten US Army installations from 1991 to 2018 to produce rate ratios for estimation of future climate change impacts. In this chapter, we identified positive long-term associations between annual heat indices and heat stress illness hospitalization and reportable event outcomes. Chapter 3 assessed incident active-duty US military heat stress illness cases at 24 installations between 1998 and 2019 on a daily-scale, resulting in odds ratio exposure-lag-response curves applicable to near-term risk assessment. The daily-scale relationships betweenheat indices and case-defined heat stress illnesses were non-linear, with increasing odds ratios starting from mild temperature ranges, and displayed short-term delayed effects. Finally, Chapter 4 described demographic and body composition risk factor trends in the US military from 1998 to 2019. In this assessment, we identified a null trend for body mass index among heat stress illness subjects over the study period. Overall, our findings demonstrate a connection between temperature and humidity indicators and observed heat stress illness morbidity outcomes among multiple sets of indices and timescales. This dissertation highlights an urgent need for vigilant heat stress prevention and control measures to protect health and maintain performance in hot and humid environments.

Exposure to high heat and humidity can lead to serious health risks, including heat exhaustion and heat stroke. Wet Bulb Globe Temperature (WBGT) and heat index have historically been used to predict heat stress events, but individualized factors are not included in the measurement. It has been shown that there is a relationship between cardiovascular measurements and heat stress, which could be used to measure heat stress risk on an individual level. Research has been done to find relationships between cardiovascular metrics in a workplace environment, however the study did not include the use of a controlled environment as a baseline. This study provides measurements of transepidermal water loss (TEWL), heart rate, body core temperature, and blood pressure in a controlled environment when human subjects are exposed to high heat and humidity. Thirty subjects (n=17 females, 13 males) were asked to self-express their activity level (active vs. sedentary), gender, and age. The subjects performed a 30-minute moderate exercise routine on a stationary stepper machine in a heated environmental chamber (average WBGT of 26ºC). TEWL, heart rate, tympanic temperature, and blood pressure were recorded at every 10-minute increment of the exercise protocol per subject. The data was analyzed using JMP® software to find significant (P