Suspected exertional heat stroke; A case study of worker cooling in a hot and humid field environment.

BACKGROUND: In the event of a severe occupational heat-related illness, paramedic assistance may not be immediately available. A worker's survival may depend on their co-workers access to efficacious field-based cooling modalities. One cooling method that has been claimed to be practical in field-based settings is the ice towel method. OBJECTIVES: This case study assessed the practicality of the ice towel method in an industrial setting, where criteria for use include cost effectiveness, portability, scalability, and implementation by a single worker under the stress of an emergency. METHODS: This case study describes the emergency application of the ice towel method while awaiting paramedics, for a worker suffering suspected exertional heat stroke on a remote job site. RESULTS: Ice towels were able to be transported to a remote field site and applied successfully by a single worker under the stress of a potentially life-threatening emergency. CONCLUSIONS: The ice towel method was cost effective, scalable, transportable, and rapidly applied in a field-based emergency. This case study demonstrates the importance of organizations assessing their heat-related risks, and determining controls based upon their efficacy and practicality for their unique setting.

The relative value of sociocultural and infrastructural adaptations to heat in a very hot climate in northern Australia: a case time series of heat-associated mortality.

BACKGROUND: Climate change is increasing heat-associated mortality particularly in hotter parts of the world. The Northern Territory is a large and sparsely populated peri-equatorial state in Australia. The Northern Territory has the highest proportion of Aboriginal and Torres Strait Islander people in Australia (31%), most of whom live in remote communities of over 65 Aboriginal Nations defined by ancient social, cultural, and linguistic heritage. The remainder non-Indigenous population lives mostly within the two urban centres (Darwin in the Top End region and Alice Springs in the Centre region of the Northern Territory). Here we aim to compare non-Indigenous (eg, high income) and Indigenous societies in a tropical environment and explore the relative importance of physiological, sociocultural, and technological and infrastructural adaptations to heat. METHODS: In this case time series, we matched temperature at the time of death using a modified distributed lag non-linear model for all deaths in the Northern Territory, Australia, from Jan 1, 1980, to Dec 31, 2019. Data on deaths came from the national registry of Births, Deaths and Marriages. Cases were excluded if location or date of death were not recorded or if the person was a non-resident. Daily maximum and minimum temperature were measured and recorded by the Bureau of Meteorology. Hot weather was defined as mean temperature greater than 35°C over a 3-day lag. Socioeconomic status as indicated by Index of Relative Socioeconomic Disadvantage was mapped from location at death. FINDINGS: During the study period, 34 782 deaths were recorded; after exclusions 31 800 deaths were included in statistical analysis (15 801 Aboriginal and 15 999 non-Indigenous). There was no apparent reduction in heat susceptibility despite infrastructural and technological improvements for the majority non-Indigenous population over the study period with no heat-associated mortality in the first two decades (1980-99; relative risk 1·00 [95% CI 0·87-1·15]) compared with the second two decades (2000-19; 1·14 [1·01-1·29]). Despite marked socioeconomic inequity, Aboriginal people are not more susceptible to heat mortality (1·05, [0·95-1·18]) than non-Indigenous people (1·18 [1·06-1·29]). INTERPRETATION: It is widely believed that technological and infrastructural adaptations are crucial in preparing for hotter climates; however, this study suggests that social and cultural adaptations to increasing hot weather are potentially powerful mechanisms for protecting human health. Although cool shelters are essential during extreme heat, research is required to determine whether excessive exposure to air-conditioned spaces might impair physiological acclimatisation to the prevailing environment. Understanding sociocultural practices from past and ancient societies provides insight into non-technological adaptation opportunities that are protective of health. FUNDING: None.

A Systematic Review of Post-Work Core Temperature Cooling Rates Conferred by Passive Rest.

Physical work increases energy expenditure, requiring a considerable elevation of metabolic rate, which causes body heat production that can cause heat stress, heat strain, and hyperthermia in the absence of adequate cooling. Given that passive rest is often used for cooling, a systematic search of literature databases was conducted to identify studies that reported post-work core temperature cooling rates conferred by passive rest, across a range of environmental conditions. Data regarding cooling rates and environmental conditions were extracted, and the validity of key measures was assessed for each study. Forty-four eligible studies were included, providing 50 datasets. Eight datasets indicated a stable or rising core temperature in participants (range 0.000 to +0.028 °C min-1), and forty-two datasets reported reducing core temperature (-0.002 to -0.070 °C min-1) during passive rest, across a range of Wet-Bulb Globe Temperatures (WBGT). For 13 datasets where occupational or similarly insulative clothing was worn, passive rest resulted in a mean core temperature decrease of -0.004 °C min-1 (-0.032 to +0.013 °C min-1). These findings indicate passive rest does not reverse the elevated core temperatures of heat-exposed workers in a timely manner. Climate projections of higher WBGT are anticipated to further marginalise the passive rest cooling rates of heat-exposed workers, particularly when undertaken in occupational attire.

Climate Change Effects on the Predicted Heat Strain and Labour Capacity of Outdoor Workers in Australia.

Global heating is subjecting more of the planet to longer periods of higher heat stress categories commonly employed to determine safe work durations. This study compared predicted worker heat strain and labour capacity for a recent normal climate (1986-2005) and under commonly applied climate scenarios for the 2041-2080 period for selected Australian locations. Recently published heat indices for northern (Darwin, Townsville, and Tom Price) and south-eastern coastal and inland Australia locations (Griffith, Port Macquarie, and Clare) under four projected climate scenarios, comprising two representative concentration pathways (RCPs), RCP4.5 and RCP8.5, and two time periods, 2041-2060 and 2061-2080, were used. Safe work durations, before the threshold for core temperature (38.0 °C) or sweat loss (5% body mass) are attained, were then estimated for each scenario using the predicted heat strain model (ISO7933). The modelled time to threshold core temperature varied with location, climate scenario, and metabolic rate. Relative to the baseline (1986-2005), safe work durations (labour capacity) were reduced by >50% in Port Macquarie and Griffith and by 20-50% in northern Australia. Reaching the sweat loss limit restricted safe work durations in Clare and Griffith. Projected future climatic conditions will adversely impact the predicted heat strain and labour capacity of outdoor workers in Australia. Risk management strategies must adapt to warming conditions to protect outdoor workers from the deleterious effects of heat.

Indicators to assess physiological heat strain - Part 3: Multi-country field evaluation and consensus recommendations.

In a series of three companion papers published in this Journal, we identify and validate the available thermal stress indicators (TSIs). In this third paper, we conducted field experiments across nine countries to evaluate the efficacy of 61 meteorology-based TSIs for assessing the physiological strain experienced by individuals working in the heat. We monitored 372 experi-enced and acclimatized workers during 893 full work shifts. We continuously assessed core body temperature, mean skin temperature, and heart rate data together with pre/post urine specific gravity and color. The TSIs were evaluated against 17 published criteria covering physiological parameters, practicality, cost effectiveness, and health guidance issues. Simple meteorological parameters explained only a fraction of the variance in physiological heat strain (R2 = 0.016 to 0.427; p < 0.001), reflecting the importance of adopting more sophisticated TSIs. Nearly all TSIs correlated with mean skin temperature (98%), mean body temperature (97%), and heart rate (92%), while 66% of TSIs correlated with the magnitude of dehydration and 59% correlated with core body temperature (r = 0.031 to 0.602; p < 0.05). When evaluated against the 17 published criteria, the TSIs scored from 4.7 to 55.4% (max score = 100%). The indoor (55.4%) and outdoor (55.1%) Wet-Bulb Globe Temperature and the Universal Thermal Climate Index (51.7%) scored higher compared to other TSIs (4.7 to 42.0%). Therefore, these three TSIs have the highest potential to assess the physiological strain experienced by individuals working in the heat.

Indicators to assess physiological heat strain - Part 1: Systematic review.

In a series of three companion papers published in this Journal, we identify and validate the available thermal stress indicators (TSIs). In this first paper of the series, we conducted a systematic review (registration: INPLASY202090088) to identify all TSIs and provide reliable information regarding their use (funded by EU Horizon 2020; HEAT-SHIELD). Eight databases (PubMed, Agricultural and Environmental Science Collection, Web of Science, Scopus, Embase, Russian Science Citation Index, MEDLINE, and Google Scholar) were searched from database inception to 15 April 2020. No restrictions on language or study design were applied. Of the 879 publications identified, 232 records were considered for further analysis. This search identified 340 instruments and indicators developed between 200 BC and 2019 AD. Of these, 153 are nomograms, instruments, and/or require detailed non-meteorological information, while 187 can be mathematically calculated utilizing only meteorological data. Of these meteorology-based TSIs, 127 were developed for people who are physically active, and 61 of those are eligible for use in occupational settings. Information regarding the equation, operating range, interpretation categories, required input data, as well as a free software to calculate all 187 meteorology-based TSIs is provided. The information presented in this systematic review should be adopted by those interested in performing on-site monitoring and/or big data analytics for climate services to ensure appropriate use of the meteorology-based TSIs. Studies two and three in this series of companion papers present guidance on the application and validation of these TSIs, to guide end users of these indicators for more effective use.

Indicators to assess physiological heat strain - Part 2: Delphi exercise.

In a series of three companion papers published in this Journal, we identify and validate the available thermal stress indicators (TSIs). In this second paper of the series, we identified the criteria to consider when adopting a TSI to protect individuals who work in the heat, and we weighed their relative importance using a Delphi exercise with 20 experts. Two Delphi iterations were adequate to reach consensus within the expert panel (Cronbach's α = 0.86) for a set of 17 criteria with varying weights that should be considered when adopting a TSI to protect individuals who work in the heat. These criteria considered physiological parameters such as core/skin/mean body temperature, heart rate, and hydration status, as well as practicality, cost effectiveness, and health guidance issues. The 17 criteria were distributed across three occupational health-and-safety pillars: (i) contribution to improving occupational health (55% of total importance), (ii) mitigation of worker physiological strain (35.5% of total importance), and (iii) cost-effectiveness (9.5% of total importance). Three criteria [(i) relationship of a TSI with core temperature, (ii) having categories indicating the level of heat stress experienced by workers, and (iii) using its heat stress categories to provide recommendations for occupational safety and health] were considered significantly more important when selecting a TSI for protecting individuals who work in the heat, accumulating 37.2 percentage points. These 17 criteria allow the validation and comparison of TSIs that presently exist as well as those that may be developed in the coming years.

Heat Health Management in a Quarantine and Isolation Facility in the Tropics.

INTRODUCTION: The Howard Springs Quarantine Facility (HSQF) is located in tropical Northern Australia and has 875 blocks of four rooms (3,500 rooms in total) spread over 67 hectares. The HSQF requires a large outdoor workforce walking outdoor pathways to provide individual care in the ambient climate. The personal protective equipment (PPE) required for the safety of quarantine workers varies between workgroups and limits body heat dissipation that anecdotally contributes to excessive sweating, which combined with heat stress symptoms of fatigue, headache, and irritability, likely increases the risk of workplace injuries including infection control breaches. STUDY OBJECTIVE: The purpose of this study was the description of qualitative and quantitative assessment for HSQF workers exposed to tropical environmental conditions and provision of evidenced-based strategies to mitigate the risk of heat stress in an outdoor quarantine and isolation workforce. METHODS: The study comprised two components - a cross-sectional physiological monitoring study of 18 workers (eight males/ten females; means: 41.4 years; 1.69m; 80.6kg) during a single shift in November 2020 and a subjective heat health survey completed by participants on a minimum of four occasions across the wet season/summer period from November 2020 through February 2021. The physiological monitoring included continuous core temperature monitoring and assessment of fluid balance. RESULTS: The mean apparent temperature across first-half and second-half of the shift was 34.7°C (SD = 0.8) and 35.6°C (SD = 1.9), respectively. Across the work shift (mean duration 10.1 hours), the mean core temperature of participants was 37.3°C (SD = 0.2) with a range of 37.0°C - 37.7°C. The mean maximal core temperature of participants was 37.7°C (SD = 0.3). In the survey, for the workforce in full PPE, 57% reported feeling moderately, severely, or unbearably hot compared to 49% of those in non-contact PPE, and the level of fatigue was reported as moderate to severe in just over 25% of the workforce in both groups. CONCLUSION: Heat stress is a significant risk in outdoor workers in the tropics and is amplified in the coronavirus disease 2019 (COVID-19) frontline workforce required to wear PPE in outdoor settings. A heat health program aimed at mitigating risk, including workplace education, limiting exposure times, encouraging hydration, buddy system, active cooling, and monitoring, is recommended to limit PPE breaches and other workplace injuries in this workforce.

Influence of age, geographical region, and work unit on heat strain symptoms: a cross-sectional survey of electrical utility workers.

This study assessed self-reported heat strain symptoms in workers of a state wide electrical utility distributor to determine risk differences between age groups, geographical work regions and work units. Out of a total 3,250 workers, 918 (∼28%) outdoor staff completed an online survey, which assessed the frequency of self-reported heat strain symptoms in the work and post-work settings, factors contributing to symptoms and symptom management. Heat strain symptoms were grouped into chronic low-grade cases and isolated high-grade cases based on the severity and frequency of symptoms. The risk (likelihood) of an employee being classified as either a chronic low-grade or isolated high-grade case was calculated and compared to the mean risk of all categories to determine risk difference, expressed as -1.00 to 1.00. For chronic low-grade cases, the 41-50 years age group had significantly increased risk (+0.08, p < 0.05) while the over 60 years age group had significantly decreased risk (-0.14, p < 0.05). Two of the three regions (p < 0.01) and three of the nine work units also demonstrated risk differences (p < 0.01) for chronic low-grade cases. Work units were the sole grouping to demonstrate risk difference for isolated high-risk cases. Work units with greater exposure to heat and higher requirement for protective clothing, such as Underground (+0.19, p < 0.05), Overhead - Predominantly Live Line (+0.18, p < 0.01), and Overhead - Distribution and Transmission (+0.11, p < 0.05) were at greater risk of reporting heat stress symptoms. This study demonstrates that the pattern of self-reported chronic low-grade heat strain cases differs to isolated high-grade cases within the electrical utility industry. Age, geographical location, and work unit independently alter the risk of chronic low-grade heat strain, while the risk of isolated high-grade heat strain was only related to work unit. These outcomes support implementation of a flexible and targeted approach to heat stress management in large and diverse organizations in which employees are routinely exposed to heat.

COVID-19 and thermoregulation-related problems: Practical recommendations.

The COVID-19 pandemic started in the cold months of the year 2020 in the Northern hemisphere. Concerns were raised that the hot season may lead to additional problems as some typical interventions to prevent heat-related illness could potentially conflict with precautions to reduce coronavirus transmission. Therefore, an international research team organized by the Global Health Heat Information Network generated an inventory of the specific concerns about this nexus and began to address the issues. Three key thermal and covid-19 related topics were highlighted: 1) For the general public, going to public cool areas in the hot season interferes with the recommendation to stay at home to reduce the spread of the virus. Conflicting advice makes it necessary to revise national heat plans and alert policymakers of this forecasted issue. 2) For medical personnel working in hot conditions, heat strain is exacerbated due to a reduction in heat loss from wearing personal protective equipment to prevent contamination. To avoid heat-related injuries, medical personnel are recommended to precool and to minimize the increase in body core temperature using adopted work/rest schedules, specific clothing systems, and by drinking cold fluids. 3) Fever, one of the main symptoms of COVID-19, may be difficult to distinguish from heat-induced hyperthermia and a resting period may be necessary prior to measurement to avoid misinterpretation. In summary, heat in combination with the COVID-19 pandemic leads to additional problems; the impact of which can be reduced by revising heat plans and implementing special measures attentive to these compound risks.

The impact of perceived heat stress symptoms on work-related tasks and social factors: A cross-sectional survey of Australia's Monsoonal North.

Heat poses a significant occupational hazard for labour-intensive workers in hot and humid environments. Therefore, this study measured the prevalence of heat-stress symptoms and impact of heat exposure on labour-intensive industries within the Monsoonal North region of Australia. A cohort of 179 workers completed a questionnaire evaluating environmental exposure, chronic (recurring) and/or severe (synonymous with heat stroke) symptoms of heat stress, and impact within work and home settings. Workers reported both chronic (79%) and severe (47%) heat stress symptoms, with increased likelihood of chronic symptoms when exposed to heat sources (OR 1.5-1.8, p = 0.002-0.023) and decreased likelihood of both chronic and severe symptoms when exposed to air-conditioning (Chronic: OR 0.5, p = <0.001, Severe: OR 0.7, p = 0.019). Negative impacts of heat exposure were reported for both work and home environments (30-60% respectively), highlighting the need for mitigation strategies to reduce occupational heat stress in the Monsoonal North.

Are Recommended Heat Stroke Treatments Adequate for Australian Workers?

Workers that combine physical exertion with exposure to hot conditions are susceptible to heat-related illnesses, including heat stroke. Despite recognition of cold water immersion as the heat stroke treatment of choice in the peer-reviewed literature, it was not included within recommended treatments of leading Australian healthcare training organizations and was omitted from Safe Work Australia's recently updated 'Managing the risks of working in heat' guidance material. On this basis, the guidance material appears an opportunity lost to assist Australian industry transition their heat stroke management to reflect the evidence. It is recommended that Australian providers of healthcare training, and those reliant on such information, review the efficacy of their heat stroke treatments.

Should Workers Avoid Consumption of Chilled Fluids in a Hot and Humid Climate?

Despite provision of drinking water as the most common method of occupational heat stress prevention, there remains confusion in hydration messaging to workers. During work site interactions in a hot and humid climate, workers commonly report being informed to consume tepid fluids to accelerate rehydration. When questioned on the evidence supporting such advice, workers typically cite that fluid absorption is delayed by ingestion of chilled beverages. Presumably, delayed absorption would be a product of fluid delivery from the gut to the intestines, otherwise known as gastric emptying. Regulation of gastric emptying is multifactorial, with gastric volume and beverage energy density the primary factors. If gastric emptying is temperature dependent, the impact of cooling is modest in both magnitude and duration (≤ 5 minutes) due to the warming of fluids upon ingestion, particularly where workers have elevated core temperature. Given that chilled beverages are most preferred by workers, and result in greater consumption than warm fluids during and following physical activity, the resultant increased consumption of chilled fluids would promote gastric emptying through superior gastric volume. Hence, advising workers to avoid cool/cold fluids during rehydration appears to be a misinterpretation of the research. More appropriate messaging to workers would include the thermal benefits of cool/cold fluid consumption in hot and humid conditions, thereby promoting autonomy to trial chilled beverages and determine personal preference. In doing so, temperature-based palatability would be maximized and increase the likelihood of workers maintaining or restoring hydration status during and after their work shift.

Characteristics of trauma mortality in the Northern Territory, Australia.

BACKGROUND: While factors including remoteness, alcohol consumption, age and Indigenous ethnicity are well-documented associations of trauma mortality, less is known of trauma seasonality. This is particularly relevant to Australia's Northern Territory, with its tropical regions experiencing a climate of wet (hot and humid) and dry (warm) seasons annually. The aim of this study was to therefore, examine the characteristics of trauma mortality in the Top End, Northern Territory, Australia. METHODS: A retrospective review of the National Coroners Information System (NCIS) database from 1 January 2003 to 31 December 2007 analysed four-hundred and sixteen traumatic deaths where the trauma event and death occurred within the Top End of the Northern Territory. RESULTS: The annual traumatic death rate for the Top End was 58.7 per 100 000, with variance between regions (accessible 38.1; remote 119.1 per 100000, respectively). Overall alcohol was involved in 56.5% of cases. The three most frequent mechanisms of death were suicide, transport related and assault, accounting for 81.5% of deaths. These respective mechanisms of death demonstrated seasonal influence, with transport related deaths 2.5 times more likely to occur in the dry than the wet season (p < 0.001), while assault related deaths were 3.3 times more likely to occur during the wet season (p = 0.005), and suicide was 1.6 times more likely to occur during the wet season (p = 0.022). Transport related deaths were 2.2 times more likely in remote and very remote settings than in accessible or moderately accessible regions (p < 0.003), whereas death by suicide was less likely to occur in remote and very remote regions than in accessible or moderately accessible areas (p = 0.012). CONCLUSION: Excessively high rates of traumatic death in the Top End of the Northern Territory were evident, with contrasting seasonal and regional profiles. Based upon the data of this investigation, existing programmes to minimise trauma in the Northern Territory ought to be evaluated for seasonal and regional specificity.

Perception or reality: Can thermal perceptions inform management of firefighters in the heat?

Accurately assessing the physiological status of firefighters during work in the heat is critical to ensuring their safety. Evaluating core temperatures (Tc) in the field is problematic due to cost and limitations in technology and accuracy. As such, fire services rely on individual perceptions of wellbeing. The present study aimed to establish whether perceptual responses measured using the perceptual strain index (PeSI), calculated from rate of perceived exertion (RPE) and thermal sensation (TS), could reliably predict the physiological strain (PSI) encountered by experienced firefighters working in a hot environment. We conducted two firefighting simulations (set-pace and self-paced) in a purposefully built heat chamber (100 ± 5°C) comprised of two 20-min periods separated by a 10-min recovery outside the chamber. Physiological strain was measured via heart rate (HR) and gastrointestinal temperature (Tgi) and compared with PeSI at 5-min intervals. To evaluate the predictive ability of the PeSI for PSI, mean differences and the 95% limits of agreement (LOA) were established, along with correlation coefficients at each 5-min interval. Moderately significant correlations occurred in the second work bout of the self-paced trial only (10 min: r = 0.335, 15 min: r = 0.498, 20 min r = 0.439) with no other correlations observed at any other time during either trial or during the rest periods. Bland-Altman analysis revealed mean differences of -0.74 ± 2.70 (self-paced) and +0.04 ± 2.04 (set-paced) between PeSI and PSI with the 95% LOA being -4.77 to 3.28 (self-paced) and -4.01 to 2.01 (set-paced). The wide LOA and lack of correlations observed between perceptual and physiological strain in both self-paced and set-paced work trials indicate that PeSI is not sufficiently reliable as a sole measure of wellbeing for firefighters working in the heat. Hence, we recommend that fire services prioritise the development of reliable and effective monitoring tools for use in the field.

Influence of Chronic Heat Acclimatization on Occupational Thermal Strain in Tropical Field Conditions.

OBJECTIVE: To examine whether non-heat acclimatized (NHA) emergency responders endure greater physiological and perceptual strain than heat acclimatized (HA) counterparts in tropical field settings. METHODS: Eight HA and eight NHA men urban search and rescue personnel had physiological and perceptual responses compared during the initial 4 hours shift of a simulated disaster in tropical conditions (ambient temperature 34.0 °C, 48% relative humidity, wet bulb globe temperature [WBGT] 31.4 °C). RESULTS: From the 90th minute through to end of shift, HA (38.5 °C) sustained a significantly higher gastrointestinal temperature than NHA (38.1 °C) (mean difference 0.4 ±â€Š0.2 °C, 95% confidence interval [CI] 0.2 to 0.7 °C, P = 0.005) despite comparable heart rate (P = 0.30), respiratory rate (P = 0.88), and axilla skin temperature (P = 0.47). Overall, perception of body temperature was similar between cohorts (P = 0.87). CONCLUSIONS: The apparent tolerance of greater physiological strain by HA responders occurred in the absence of perceptual differences.

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.

Pre-deployment Heat Acclimatization Guidelines for Disaster Responders.

INTRODUCTION: Minimal preparation time is a feature of responding to sudden onset disasters. While equipment and supplies are prepared for deployment at short notice, less is known of the physical preparation of medical responders. With many disaster-prone areas classified as tropical regions, there is potential for responders to endure a combination of high ambient temperatures and relative humidity during deployment. Heat acclimatization, defined as the physiological and perceptual adaptations to frequent elevations of core body temperature (Tc), is a key strategy to improve tolerance of hot conditions by medical responders. METHODS: Pre-deployment heat acclimatization guidelines were developed based upon the duration of physical training and the subjective rate of perceived exertion (session RPE). An objective of individual training sessions was the perception of body temperature as warm to hot. The guidelines were implemented for Team Bravo (2nd rotation) of the Australian Medical Assistance Team (AusMAT) deployed to Tacloban, Philippines following Typhoon Haiyan in November 2013. The guidelines were distributed electronically five to seven days prior to deployment and were followed by a consultation. A group training session in hot conditions was undertaken prior to departure. RESULTS: The AusMAT responders to utilize the guidelines were based in cool or temperate climates that required extra layers of clothing, training during warmer parts of the days, or warm indoor conditions to achieve session objectives. Responders reported the guidelines were simple to use, applicable to their varied training regimens, and had improved their confidence to work in the heat despite not completing the entire 14 day period. CONCLUSION: The pre-deployment heat acclimatization guidelines provided AusMAT responders the ability to quantify their physical training and promoted physiological adaptations to maximize health, safety, and performance during deployment. While maintaining year-round heat acclimatization is considered essential for medical responders, these guidelines may facilitate beneficial adaptations once notified of deployment.

Water immersion for post incident cooling of firefighters; a review of practical fire ground cooling modalities.

Rapidly cooling firefighters post emergency response is likely to increase the operational effectiveness of fire services during prolonged incidents. A variety of techniques have therefore been examined to return firefighters core body temperature to safe levels prior to fire scene re-entry or redeployment. The recommendation of forearm immersion (HFI) in cold water by the National Fire and Protection Association preceded implementation of this active cooling modality by a number of fire services in North America, South East Asia and Australia. The vascularity of the hands and forearms may expedite body heat removal, however, immersion of the torso, pelvis and/or lower body, otherwise known as multi-segment immersion (MSI), exposes a greater proportion of the body surface to water than HFI, potentially increasing the rates of cooling conferred. Therefore, this review sought to establish the efficacy of HFI and MSI to rapidly reduce firefighters core body temperature to safe working levels during rest periods. A total of 38 studies with 55 treatments (43 MSI, 12 HFI) were reviewed. The core body temperature cooling rates conferred by MSI were generally classified as ideal (n = 23) with a range of ~0.01 to 0.35 °C min(-1). In contrast, all HFI treatments resulted in unacceptably slow core body temperature cooling rates (~0.01 to 0.05 °C min(-1)). Based upon the extensive field of research supporting immersion of large body surface areas and comparable logistics of establishing HFI or MSI, it is recommended that fire and rescue management reassess their approach to fireground rehabilitation of responders. Specifically, we question the use of HFI to rapidly lower firefighter core body temperature during rest periods. By utilising MSI to restore firefighter Tc to safe working levels, fire and rescue services would adopt an evidence based approach to maintaining operational capability during arduous, sustained responses. While the optimal MSI protocol will be determined by the specifics of an individual response, maximising the body surface area immersed in circulated water of up to 26 °C for 15 min is likely to return firefighter Tc to safe working levels during rest periods. Utilising cooler water temperatures will expedite Tc cooling and minimise immersion duration.