A novel vest with dual functions for firefighters: combined effects of body cooling and cold fluid ingestion on the alleviation of heat strain

Farmworker Acceptability of Backpack Hydration Systems

OBJECTIVE

To improve water access while working and contribute to fewer heat-related illnesses (HRI), backpack hydration systems were provided to over 200 farmworkers to use during the 2022 growing season. Acceptability of the water intake intervention was assessed among farmworkers in eastern North Carolina, USA.

METHODS

With a pre-established community-university partnership, the acceptability of the intervention was assessed using a cross-sectional survey. The backpack brand selected included a 3-liter water bladder and attached drinking hose. Data analysis included descriptive and correlation statistics.

RESULTS

Among 47 male, migrant farmworkers, most (90%) reported the hydration backpack to be acceptable or completely acceptable to workplace fluid intake. Most (53%) reported using the backpack some of the time, compared to 28% who used it often. The participants reported an average of 4.8 (SD 2.2) liters of water intake from the backpack on a typical workday. Most reported the backpack improved the quantity and frequency of their water consumption.

CONCLUSION

This study was an important first step in implementation of hydration backpack systems as an HRI-preventative intervention among farmworkers. Future interventional studies could assess the efficacy of the backpacks on health outcomes, including incidence of dehydration and symptoms of HRI.

Development of a new testing protocol to evaluate cooling systems

Thermal comfort is defined as the user's sensation of thermal well-being. This sensation can be modified by extreme environmental conditions changing the body temperature of the user. Different mechanisms, the thermoregulatory system itself or an external textile system, are required to allow the body to return to their state of well-being. A cooling vest is an example of a smart garment that helps to reduce the user's body temperature in situations of heat stress. There are two different standards to evaluate the performance of this type of clothing: the ASTM F2371-16 standard that uses a thermal manikin and the ASTM F2300-10 standard that uses human subjects for the evaluation. There is a need for simple, objective and affordable tests to evaluate the thermal comfort associated with personal protective equipment use. The aim of this work is to develop a new testing method that combines a thermal manikin with a simulation software and allows to study physiological parameters of a human subject in the body of the thermal manikin.

Impact of different personal protective clothing for firefighters in mountain areas

BACKGROUND

Mountain hiking is an unpredictable activity for firefighters during the search, rescue, and firefighting. Could the quality of the uniform worn by firefighters affect psychophysiological variables?

OBJECTIVE

The objective of this study was to monitor the responses of perceived exertion (RPE), musculoskeletal pain (MP), and heart rate variability (HRV) responses in firefighters using different uniforms on a 5 km mountain walking activity. The feeling of comfort, safety, and ergonomic adjustment of the two types of uniforms also was verified.

METHODS

Sixteen firefighters were divided into two groups: 4thRUPM"B2" (33% polyester and 67% cotton) vs. GOLD (50% polyamide and 50% cotton). The GOLD group wore a prototype that had not yet been operationally tested.

RESULTS

The independent t-test showed that the groups had similar results in RPE at post-march (Omni-Walk/Run = 3.5±0.9 vs. 2.9±0.6 AU). ANOVA Two-way (2x group and 2x time) was used to verify differences in body mass (BM), MP, and HRV. There was a main effect of time (pre vs. post-march; p < 0.05) for BM, MP, heart rate (HR), mean RR, RMSSD, pNN50, and HF, regardless of group (4thRUPM"B2" vs. GOLD). Rainwater increased post-march BM (92.2±9.8 kg vs. 93.5±9.9 kg). MP (28.9±2.9 vs 33.2±7.7 AU), HR (71.6±14.2 vs 99.0±26.3 bpm), RMSSD (74.8±53.7 vs 126.5±74.4 ms) and HF (48.5±20.2 vs 60.0±16.7 nu) also increased post-march. The mean RR (875.2±153.3 vs. 673.9±155.3 ms) and pNN50 (33.1±18.6 vs. 46.3±23.9%) reduced post-march. There was a subjective preference for GOLD.

CONCLUSION

Different uniforms do not compromise psychophysiological variables during the mountain hike but differentiate ergonomic subjectivity.

Cooling Between Exercise Bouts and Post-exercise With the Fan Cooling Jacket on Thermal Strain in Hot-Humid Environments

This study investigated the effects of cooling between exercise bouts and post-exercise with a commercially available fan cooling jacket on thermal and perceptual responses during and following exercise in hot-humid environments. Ten male athletes completed two 30 min cycling bouts at a constant workload (1.4 watts⋅kg^-1 of body mass) with a 5 min recovery period in between. Exercise was followed by a 10 min recovery period. In an environmental chamber (33°C, 65% relative humidity), participants performed two trials with (FCJ) or without (CON) the fan cooling jacket on a T-shirt during the 5 min inter-exercise and 10 min post-exercise recovery periods. Mean, chest and upper arm skin temperatures, and thermal sensation and comfort were lower in FCJ than CON trial during and following exercise (P < 0.05). Thigh and calf skin temperatures, infrared tympanic temperature and heart rate were lower in FCJ than CON trial during the experimental trials (P < 0.05). The rates of fall in mean, chest and upper arm skin temperatures, infrared tympanic temperature and thermal sensation and comfort were faster in FCJ than CON trial during both recovery periods (P < 0.05). There were faster rates of fall in thigh and calf skin temperatures and heart rate in FCJ than CON trial during the post-exercise recovery period (P < 0.05). No difference was observed between trials in the rating of perceived exertion (P > 0.05). This study indicates that cooling between exercise bouts and post-exercise with the fan cooling jacket would effectively mitigate thermal strain and perception/discomfort during and following exercise in hot-humid environments. This garment would reduce whole-body skin temperature quickly while promoting falls in lower-body as well as upper-body skin temperatures.

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.