@article{gao_deaton_barker_denhartog_fang_2024, title={Effects of incident solar radiation on evaporative heat loss through firefighter turnout composites incorporating microporous and bi-component type moisture barrier components}, volume={2}, ISSN={["1754-2340"]}, DOI={10.1080/00405000.2024.2318501}, abstractNote={Solar radiation is a significant source of firefighter heat stress. In this study, the influence of solar radiation on heat transfer through firefighter fabric composites was evaluated using a modified sweating guarded hotplate exposed to simulated solar radiation. It demonstrated that the heat transfer depended on the intensity of the incident radiation, the color of the outer shell materials, and the type of moisture barrier incorporated in the composite. For ensembles with microporous moisture barrier, evaporative resistance decreased steadily with radiation. In contrast, the evaporative resistance of firefighter ensembles with bi-component moisture barriers initially increased in lower-level radiation intensity and then dropped as the exposure became more intense. To the best of our knowledge, these have never been reported before. The new findings from this study demonstrate the need to address the property change in bi-component moisture barriers under radiant heat load in material design, testing, and mathematical modeling.}, journal={JOURNAL OF THE TEXTILE INSTITUTE}, author={Gao, Huipu and Deaton, Anthoney Shawn and Barker, Roger L. and DenHartog, Emiel and Fang, Xiaomeng}, year={2024}, month={Feb} } @article{gao_deaton_barker_2024, title={Impact of Durable Water-Repellent Finishing in Thermal Liner on Firefighter Heat Stress}, ISSN={["2330-5517"]}, DOI={10.1177/24723444241237313}, abstractNote={Heat stress has always been a critical issue among firefighters. Previous studies have indicated the potential influence of water-repellent finishing on heat release properties of clothing. Nevertheless, the impact of durable water repellent in a thermal liner on firefighter heat stress has never been studied. In this work, the impact of durable water-repellent finishing inside the thermal liner on heat stress has been evaluated systematically for the first time, using a sweat-guarded hotplate, a sweating manikin, and a physiological manikin. The results showed that there was no significant difference in heat loss capabilities on the fabric level or garment level between turnout clothing with or without durable water-repellent finishing in the thermal liner. In addition, no significant differences were identified in predicted physiological responses when tested in a mild environment. However, the turnout clothing with durable water-repellent finishing in the thermal liner demonstrated significantly less weight gain after the physiological manikin test. This initial investigation lays the groundwork for understanding how durable water-repellent finishing in thermal liners may impact firefighter comfort. It acts as a starting point for further research on the potential impact of durable water-repellent finishing on thermal protection and overall comfort under various ambient conditions.}, journal={AATCC JOURNAL OF RESEARCH}, author={Gao, Huipu and Deaton, Anthoney Shawn and Barker, Roger}, year={2024}, month={Mar} } @article{gao_deaton_barker_2022, title={A new test method for evaluating the evaporative cooling efficiency of fabrics using a dynamic sweating hot plate}, volume={33}, ISSN={["1361-6501"]}, DOI={10.1088/1361-6501/ac84f7}, abstractNote={Abstract The lack of direct measures of the ability of a fabric to cool the skin by liquid sweat evaporation is a critical gap in available laboratory tests for evaluating the comfort of active wear clothing materials. This paper describes a novel method designed to evaluate the evaporative cooling performance of fabrics in a protocol that simulates active wear, including sweating and drying periods, in a continuous one-step procedure. It uses a dynamic sweating hot plate to measure the latent heat absorbed by fabrics in sweat evaporation, and in drying after sweat absorption. The efficacy of the method is demonstrated using a selected set of high-wicking polyester and a cotton knit t-shirt material that have different moisture absorption, wicking and drying properties. The cooling efficiency test shows that high-wicking polyester fabrics provide larger evaporative cooling in the sweating phase, where it is more likely to convey cooling benefits to the skin. Cotton fabrics absorb more latent heat in the drying phase, where the cooling effect may contribute to chilling effects. It provides an ideal platform to observe the dynamic relationship between patterns of wicking and liquid moisture spreading in fabrics and the evaporative cooling provided by the test materials. It shows that the location of wicked moisture in the fabric is a critical determinant of potential cooling effects. It also shows that a fabric’s wicking ability is not always an accurate predictor of its cooling efficiency. This new test method has provided a unique tool for directly characterizing the cooling efficiency of clothing materials using a protocol that accurately simulates sweating generation and drying in actual active wear scenarios.}, number={12}, journal={MEASUREMENT SCIENCE AND TECHNOLOGY}, author={Gao, Huipu and Deaton, A. Shawn and Barker, Roger}, year={2022}, month={Dec} } @article{gao_deaton_barker_denhartog_fang_2022, title={Effects of Air Gaps on Heat Loss through Firefighter Turnout Composites with Different Moisture Barrier Components}, volume={10}, ISSN={["1875-0052"]}, DOI={10.1007/s12221-022-0420-z}, journal={FIBERS AND POLYMERS}, author={Gao, Huipu and Deaton, Anthoney Shawn and Barker, Roger and DenHartog, Emiel and Fang, Xiaomeng}, year={2022}, month={Oct} } @article{gao_deaton_fang_barker_denhartog_watson_2022, title={Effects of Outer Shell Fabric Color, Smoke Contamination, and Washing on Heat Loss through Turnout Suit Systems}, volume={92}, ISSN={0040-5175 1746-7748}, url={http://dx.doi.org/10.1177/00405175211073353}, DOI={10.1177/00405175211073353}, abstractNote={ Firefighters frequently have to work in direct solar radiant heat. To reduce firefighter heat stress, the influence of turnout garment properties on heat gain from solar radiation must be understood. This research studied the effects of color, texture, washing, and contamination of outer shell fabrics on heat loss through firefighter turnout fabric materials in simulated solar exposures. It showed that solar radiation could be a major factor in heat loss through turnout suits. Solar radiation equivalent to a sunny day completely reversed heat exchange through the turnout fabric systems, converting a heat loss of about 240 W/m2 to a heat gain exceeding 100 W/m2. Solar radiation caused turnout fabric systems to dry out and this decreased the performance of turnout systems that incorporated bi-component moisture barriers. Most significantly, the color of the outer shell had a major influence on lowering turnout heat loss in solar exposures. Composites with a black-dyed outer shell absorbed more solar energy than composites with lighter colored shell materials. Soot and fire-ground contaminants present on turnout outer shell fabrics also reduced heat loss under solar exposure. The findings of this study answered long-standing questions about the importance of turnout fabric color on heat exchange with the environment. The results provide additional motivation for efficient turnout cleaning practices, not only to reduce potentially toxic exposure to smoke contaminants, but to reduce turnout-gear-related heat strain on firefighters. }, number={11-12}, journal={Textile Research Journal}, publisher={SAGE Publications}, author={Gao, Huipu and Deaton, A. Shawn and Fang, Xiaomeng and Barker, Roger L. and DenHartog, Emiel and Watson, Kyle}, year={2022}, month={Jan}, pages={1909–1922} } @article{gao_deaton_barker_fang_watson_2022, title={Effects of the moisture barrier and thermal liner components on the heat strain and thermal protective performance of firefighter turnout systems}, volume={5}, ISSN={["1746-7748"]}, url={https://doi.org/10.1177/00405175221099947}, DOI={10.1177/00405175221099947}, abstractNote={ An ideal firefighter turnout system should be capable of releasing body heat to prevent heat stress, indicated by THL (total heat loss) and Ref (evaporative resistance) indexes, while maintaining high thermal protective performance (TPP). Our study found no correlations between THL and Ref, or between Ref and TPP. The results showed that, when tested in the mild condition as in the standard THL test method, turnout systems with bi-component moisture barriers exhibited an advantage in THL that did not translate to more thermally stressful hot environments. A physiological manikin was used to understand the effect of turnout clothing systems on heat strain in different environmental conditions and the value of utilizing Ref or THL to predict heat strain performance. We found no difference in heat strain performance between composites with one-layer and two-layer spunlace thermal liners in mild or hot conditions. It showed that both THL and Ref had their limitations: THL only predicted thermal burden in mild environments, while Ref was only correlated in hot conditions. Thus, the exclusive reliance on either index could increase the risk of heat stress, and we recommend incorporating the Ref heat strain index, along with THL, as dual metrics for certifying the heat strain performance of turnout suits in the NFPA 1971 standard. }, journal={TEXTILE RESEARCH JOURNAL}, author={Gao, Huipu and Deaton, A. Shawn and Barker, Roger and Fang, Xiaomeng and Watson, Kyle}, year={2022}, month={May} } @article{gao_deaton_barker_fang_watson_2022, title={Relationship between heat loss indexes and physiological indicators of turnout-related heat strain in mild and hot environments}, volume={3}, ISSN={["2376-9130"]}, url={https://doi.org/10.1080/10803548.2022.2058746}, DOI={10.1080/10803548.2022.2058746}, abstractNote={A validated physiological manikin method was used to qualify environmentally dependent correlations between firefighter turnout total heat loss (THL) and intrinsic evaporative resistance (R ef) heat strain indexes and core temperature rise in stressful work conducted in mild (25 °C, 65% relative humidity [RH]) and hot (35 °C, 40% RH; 40 °C, 28% RH) conditions. Five turnout suit constructions representing a wide range of breathability were selected. The observed correlations between measured material heat loss and core temperature showed that the THL heat strain index accurately forecast thermal burden in mild environments (<25 °C); while the R ef index provided accurate prediction in hot environments (>35 °C). They showed that the THL index did not predict heat strain in hot work environments. The findings of this study support incorporating both the R ef and THL heat strain indexes as dual metrics for characterizing the heat strain performance of turnout clothing fabrics.}, journal={INTERNATIONAL JOURNAL OF OCCUPATIONAL SAFETY AND ERGONOMICS}, publisher={Informa UK Limited}, author={Gao, Huipu and Deaton, A. Shawn and Barker, Roger and Fang, Xiaomeng and Watson, Kyle}, year={2022}, month={Apr} } @article{gao_deaton_barker_2022, title={Using a physiological manikin to evaluate the effect of foam thermal reinforcement in firefighter turnout construction on heat strain}, ISSN={["1754-2340"]}, DOI={10.1080/00405000.2022.2072139}, abstractNote={Abstract Firefighter turnout gear is a significant contributor to firefighter heat stress. This study uses a physiological manikin procedure to show how adding impermeable foam reinforcement in a firefighter suit construction can detrimentally affect firefighter heat strain. It shows that singular reliance on the THL (total heat loss) requirement called for by the NFPA (National Fire Protection Association) 1971 performance standard for firefighter gear leaves a critical gap in information needed to evaluate the heat strain contribution of reinforced turnout suit constructions. This is because THL test only measures heat loss through flat swatches of fabric used in the main body of the turnout suit construction. It does not account for the additional insulation and moisture vapor resistance of reinforcement or the overwhelming effects of garment air layers. This study demonstrates instrumented manikin testing procedures can supply the missing information in laboratory based heat strain performance testing of firefighter turnout suits.}, journal={JOURNAL OF THE TEXTILE INSTITUTE}, author={Gao, Huipu and Deaton, A. Shawn and Barker, Roger L.}, year={2022}, month={Apr} } @article{gao_deaton_fang_watson_denhartog_barker_2021, title={Effects of environmental temperature and humidity on evaporative heat loss through firefighter suit materials made with semi-permeable and microporous moisture barriers}, volume={92}, ISSN={0040-5175 1746-7748}, url={http://dx.doi.org/10.1177/00405175211026537}, DOI={10.1177/00405175211026537}, abstractNote={ The goal of this research was to understand how firefighter protective suits perform in different operational environments. This study used a sweating guarded hotplate to examine the effect of environmental temperature (20–45°C) and relative humidity (25–85% RH) on evaporative heat loss through firefighter turnout materials. Four firefighter turnout composites containing three different bi-component (semi-permeable) and one microporous moisture barriers were selected. The results showed that the evaporative resistance of microporous moisture barrier systems was independent of environmental testing conditions. However, absorbed moisture strongly affected evaporative heat loss through semi-permeable moisture barriers coated with a layer of nonporous hydrophilic polymer. Moisture absorption in mild environment (20–25°C) tests, or when testing at high humidity (>85% RH), significantly increased water vapor transmission in semi-permeable turnout systems. It was also found that environmental conditions used in the total heat loss (THL) test (25°C and 65% RH) produced moisture condensation in bi-component barrier systems, making them appear more breathable than could be expected when worn in hotter environments. Regression models successfully qualified the relationships between moisture uptake levels in semi-permeable barrier systems and evaporative resistance and THL. These findings reveal the limitations in relying on THL, the heat strain index currently called for by the NFPA 1971 Standard for Structural Firefighter personal protective equipment, and supports the need to measure turnout evaporative resistance at 35°C (Ret), in addition to THL at 25°C. }, number={1-2}, journal={Textile Research Journal}, publisher={SAGE Publications}, author={Gao, Huipu and Deaton, Anthoney Shawn and Fang, Xiaomeng and Watson, Kyle and DenHartog, Emiel A and Barker, Roger}, year={2021}, month={Jul}, pages={219–231} } @article{barker_fang_deaton_denhartog_gao_tutterow_schmid_2021, title={Identifying factors that contribute to structural firefighter heat strain in North America}, volume={28}, ISSN={1080-3548 2376-9130}, url={http://dx.doi.org/10.1080/10803548.2021.1987024}, DOI={10.1080/10803548.2021.1987024}, abstractNote={This article describes results from a survey of firefighters designed to identify conditions that contribute to heat strain in structural firefighting. Based on responses from about 3000 firefighters across the USA and Canada, the article provides invaluable information about how firefighters associate environmental conditions, work tasks and other factors with heat strain. One-half of firefighters surveyed have experienced heat stress during their service. They can wear fully deployed turnout gear for 2 h or more at the fire scene, reinforcing the importance of turnout suit breathability as a factor in heat strain. Survey results are useful in weighing the comparative value of total heat loss (THL) and evaporative heat resistance (Ref) for predicting turnout-related heat strain. Survey findings support the inclusion of a performance criterion in the National Fire Protection Association 1971 standard for firefighter personal protective equipment based on limiting Ref of turnout materials along with current THL requirement.}, number={4}, journal={International Journal of Occupational Safety and Ergonomics}, publisher={Informa UK Limited}, author={Barker, Roger and Fang, Xiaomeng and Deaton, Shawn and DenHartog, Emiel and Gao, Huipu and Tutterow, Robert and Schmid, Marni}, year={2021}, month={Nov}, pages={2183–2192} }