Papers by emiel denhartog
The Journal of The Textile Institute
Abstract Frictional characteristics of textiles play a big role in skin comfort and health, and i... more Abstract Frictional characteristics of textiles play a big role in skin comfort and health, and in the development of friction related skin injuries such as tissue deformation, skin damage, decubitus ulcers or pressure ulcers and friction blisters, especially in people with compromised skin conditions and/or immobility. All these skin injuries cause severe pain and can be life threatening. This review paper is focused on decubitus, and how friction from textiles contribute to both skin comfort, and in the formation or prevention of skin injuries such as decubitus. More than 2.5 million individuals develop decubitus annually that costs the US healthcare system $9.1-11.6 billion per year due to increased health care utilization. There’s been a significant amount of research on decubitus alone, unfortunately the role of textiles in formation and prevention of decubitus is yet understudied. This review provided an understanding of the importance of friction in textiles and skin, and factors influencing friction on respective surfaces. Along with demonstrating the mechanism of decubitus ulcer formation and some recent commendable work from textiles point of view, few critical research questions and suggestions for future work have also been provided.
Textile Research Journal
Firefighters frequently have to work in direct solar radiant heat. To reduce firefighter heat str... more 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 abso...
Filament yarns are a collection of fibers of set diameter and material held together by tension a... more Filament yarns are a collection of fibers of set diameter and material held together by tension and/or intrafilament attraction. This results in a stacking pattern that can be random with different degrees of freedom. Slight changes in tension or friction may result in a different arrangement of the microfibers in the crosssection, where the space between the fibers is filled with air. Hence, the effective thermal conductivity of the yarn would be a function of the arrangement pattern of the microfibers. We have devised a random geometry creation model in COMSOL using model methods to create random arrangements of microfibers. We vary the influencing variables while enforcing geometrical constraints and then determine the effective thermal conductivity of the yarn. The simulation then calculates the extent of the dependence of the effective thermal conductivity of the yarn cross section on different parameters.
The Journal of The Textile Institute
Abstract The purpose of this research was to determine the impact of additional textile layer rei... more Abstract The purpose of this research was to determine the impact of additional textile layer reinforcements on garment heat loss and the physiological comfort of the firefighter. Four structural firefighter turnouts with varying levels of ‘bulk’ were assessed. A base composite analysis was conducted and each suit was evaluated for thermal resistance, evaporative resistance, and overall total heat loss (THL) on a sweating thermal manikin. Raw resistance data were then modeled to predict the physiological responses of firefighters for each turnout suit. Base composite percentages were compared to the heat loss values and predicted physiological responses. The Light Weight suit along with the Control, demonstrated the greatest heat loss values and lowest rise in predicted core temperature. Overall, results depicted the harmful impact that bulky reinforcements may have on wearer physiological comfort as the Heavy Duty suit had significantly lower heat loss and a potentially fatal maximum predicted core temperature.
International Journal of Occupational Safety and Ergonomics
This paper describes results of a survey of firefighters designed to identify conditions that con... more This paper describes results of 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 United States and Canada, it 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 two or more hours on 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 the total heat loss (THL) and evaporative heat resistance (Ref) for predicting turnout related heat strain. The survey findings support the inclusion of a performance criterion in the NFPA 1971 Standard for Firefighter Personal Protective Equipment based on limiting the Ref of turnout materials along with current THL requirement.
Performance of Protective Clothing and Equipment: Innovative Solutions to Evolving Challenges
Textile Research Journal
The goal of this research was to understand how firefighter protective suits perform in different... more 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 environ...
Clothing and Textiles Research Journal
Structural firefighter prototype designs incorporating ventilation, stretch, and modularity were ... more Structural firefighter prototype designs incorporating ventilation, stretch, and modularity were developed following Watkins’ functional design process. Prototypes were designed and manufactured, including single-layer, vented, stretch, and combination prototypes. Prototype garments were evaluated for improved thermal comfort and heat loss using sweating thermal manikin assessments in two conditions: static (standing still with no wind) and dynamic (walking with wind). Raw thermal and evaporative resistance data from the manikin testing were input into a thermal modeling software system (RadTherm®) and physiological responses (core temperature, skin temperature, and sweat rate) were predicted for each prototype. A significant improvement in heat loss was measured when ventilation openings and modularity were added to the design of the clothing system. The single-layer, vented, and combination prototypes also had significantly lower increases in predicted physiological responses.
Medicine & Science in Sports & Exercise
Exposure to a variety of ubiquitous pollutants, including polycyclic aromatic hydrocarbons (PAHs)... more Exposure to a variety of ubiquitous pollutants, including polycyclic aromatic hydrocarbons (PAHs), occurs during daily exposure to vehicular exhaust fumes, smoking, grilling, and in many occupations, including firefighting. Dermal absorption of potential carcinogens has received limited attention compared to respiratory routes due to the challenges with measurement in vivo. PURPOSE: Our aims were 1) establish the efficacy of microdialysis (MD) as a sampling technique for dermal absorption of PAHs and 2) determine the effect of skin temperature on dermal absorption of the non-carcinogenic PAH, anthracene (ANT). METHODS: Two MD fibers were inserted into the ventral forearm of 6 healthy participants (32 ± 5 yrs, 5 male, 1 female) and perfused with lactated Ringers and 10% 2-hyroxypropyl-βcyclodextrin at a rate of 1 μl/min. 2% ANT cream was applied over each site, dialysate samples were collected and skin blood flow (SkBF) measured at a locally heated (HT, 43°C) and thermoneutral (TN, 33°C) site. The concentration of ANT from dialysate samples were measured via targeted tandem mass spectrometry. RESULTS: Dialysate ANT concentration was similar between the HT and TN sites (2.9 ± 0.4 vs. 3.5 ± 0.4 ppm, P=0.26). Absolute SkBF was significantly higher at the HT versus TN site (35.7 ± 11.8 and 7.2 ± 1.0 CVC, P=0.001). CONCLUSIONS: These data provide support for MD as a sampling technique for dermal absorption of PAHs. Despite similar ANT concentrations between sites, dermal absorption and sampling can be modulated by multiple factors. Further research is required to elucidate the influence of skin temperature versus clearance on dermal absorption of ANT and other PAHs. This has important implications for understanding dermal absorption of potentially carcinogenic compounds in occupational workers and the general poulation.
Journal of Materials Science
Typical liquid moisture management property tests of textiles may not represent human sweating fr... more Typical liquid moisture management property tests of textiles may not represent human sweating from sweat pores because those methods are conducted with infinite reservoirs or limited, but large amounts of liquid. For this reason, we developed a new method, ‘single-pore wicking evolution apparatus for textiles (SWEAT),’ to investigate how liquid is transported in fabrics based on within-a-yarn and yarn-to-yarn transfer wicking. This measurement system was implemented by supplying continuous liquid flow to a single yarn at a single point within the fabric substrate at a similar flow rate to a single sweat gland (approximately 50 nl/min/gland). In order to mimic the sweating phenomenon, this SWEAT test avoids the flooding liquid stage by controlling flow rate and choosing a diameter of liquid source similar to the pore size of a sweat gland. From microscopic video analysis, we found that the liquid moves along the yarns instead of making a circular wetting area, as observed in standardized tests. With the SWEAT test, we successfully measured the directional wicking rate along an individual yarn, which has not previously been reported. Furthermore, we examined not only liquid movement within-a-yarn but also yarn-to-yarn transfer of liquid because the continuously supplied liquid spills over to the adjacent yarns through the contact points.
The Journal of The Textile Institute
Abstract Mosquito resistant apparel has become increasingly sought-after due to the rise in vecto... more Abstract Mosquito resistant apparel has become increasingly sought-after due to the rise in vector-borne illnesses such as the Zika Virus, Malaria, and Dengue Fever. Botanical insect repellents have been introduced to the market for consumers that desire a natural solution involving no pesticides or added chemicals. Fabric swatches consisting of 80% nylon and 20% elastane were separately treated with an organic repellent using a patented nonwoven vessel. The fabrics were then tested for effectiveness in repelling the mosquito Aedes aegypti using an arm-in-cage assay, the most commonly used method for mosquito repellents. The repellents were also evaluated and rated by study participants according to their preference for the appeal of the scent. The treatment method is user-friendly, enabling consumers to treat their clothing with an organic insect repellent as opposed to applying a synthetic chemical to their clothing and skin. The infused fabrics showed to be effective at repelling mosquitoes for up to 8 h after repellent infusion.
Applied Ergonomics
The purpose of this study was to investigate design modifications in structural firefighter turno... more The purpose of this study was to investigate design modifications in structural firefighter turnout suits for their ability to reduce heat stress during firefighting activities. A secondary aim of this research established a benchmark for the manikin heat loss value necessary to achieve significant improvements in physiological comfort. Eight professional firefighters participated in five simulated exercise sessions wearing a control turnout suit and one of four turnout prototypes: Single Layer, Vented, Stretch, and Revolutionary. Physiological responses (internal core body temperature, skin temperature, physiological strain, heart rate, and sweat loss) were measured when wearing each turnout suit prototype. Results demonstrated a significant increase in work time and significant reductions in heat stress (core temperature, skin temperature, and physiological strain) when participants wore the Single Layer, Vented, and Revolutionary prototypes. An estimated garment heat loss value of 150 W/m2 was determined in order to achieve a significant reduction in heat stress.
Industrial health, Jan 7, 2017
To determine safe working conditions in emergency situations at petro-chemical plants in the Neth... more To determine safe working conditions in emergency situations at petro-chemical plants in the Netherlands a study was performed on three protective clothing combinations (operator's, firefighter's and aluminized). The clothing was evaluated at four different heat radiation levels (3.0, 4.6, 6.3 and 10.0 k∙W∙m) in standing and walking posture with a thermal manikin RadMan™. Time till pain threshold (43°C) is set as a cut-off criterion for regular activities. Operator's clothing did not fulfil requirements to serve as protective clothing for necessary activities at heat radiation levels above 1.5 k∙W∙m as was stated earlier by Den Hartog and Heus. With firefighter's clothing it was possible to work almost three min up to 4.6 k∙W∙m. At higher heat radiation levels firefighter's clothing gave insufficient protection and aluminized clothing should be used. Maximum working times in aluminized clothing at 6.3 k∙W∙m was about five min. At levels of 10.0 k∙W∙m (emergency c...
Textile Research Journal
Air layers in multi-layer firefighter clothing ensembles resist heat transfer from the body to th... more Air layers in multi-layer firefighter clothing ensembles resist heat transfer from the body to the environment. By reducing the volume of air between clothing layers, heat loss may be improved throughout the multi-layer firefighter turnout suit clothing system, potentially leading to reduced heat strain for the wearer. This research utilized a systems-level approach to the methodology in order to measure the effects of fabric properties and garment air gap dimensions on clothing system heat loss through specially configured turnout suit constructions. One experimental configuration incorporated a tight fitting stretchable moisture barrier garment. Another construction used thermal knit underwear to represent a closer fitting thermal liner. Air gap surface area, volume, and thickness were estimated using three-dimensional body scanning. This study showed the significant impact of fabric air permeability and clothing air gap volume on heat loss through structural firefighter suits. Te...
The Journal of The Textile Institute
Abstract The focus of this study was to establish a relationship between physical discomfort and ... more Abstract The focus of this study was to establish a relationship between physical discomfort and performance. Eleven healthy male subjects participated in this pilot study. The subjects performed a 2-h protocol without and with significant thermal and mechanical discomfort. Various cognitive tasks were executed repeatedly during the protocol to evaluate cognitive performance on memory, tracking, and vigilance tasks. Prior and after each task, subjective comfort scores were asked and objective task performance was measured. Mechanical and/or thermal discomfort only minimally influenced the overall scores for comfort. The only significant change in objective performance was a 2% increase in percentage missed stimuli during thermal discomfort. The type of task did influence the change in comfort scores, increasing the scores during the attention and memory task and decreasing during the vigilance and tracking task and fine motor tasks. Surprisingly, not discomfort, but the type of task mainly influenced the changes in comfort, discomfort became worse (increased) during easy, less challenging tasks.
Annals of Work Exposures and Health
A major concern for responders to hazardous materials (HazMat) incidents is the heat strain that ... more A major concern for responders to hazardous materials (HazMat) incidents is the heat strain that is caused by fully encapsulated impermeable (NFPA 1991) suits. In a research project, funded by the US Department of Defense, the thermal strain experienced when wearing these suits was studied. Forty human subjects between the ages of 25 and 50 participated in a protocol approved by the local ethical committee. Six different fully encapsulated impermeable HazMat suits were evaluated in three climates: moderate (24°C, 50% RH, 20°C WBGT), warm-wet (32°C, 60% RH, 30°C WBGT), and hot-dry (45°C, 20% RH, 37°C WBGT, 200 W m-2 radiant load) and at three walking speeds: 2.5, 4, and 5.5 km h-1. The medium speed, 4 km h-1, was tested in all three climates and the other two walking speeds were only tested in the moderate climate. Prior to the test a submaximal exercise test in normal clothing was performed to determine a relationship between heart rate and oxygen consumption (pretest). In total, 163 exposures were measured. Tolerance time ranged from as low as 20 min in the hot-dry condition to 60 min (the maximum) in the moderate climate, especially common at the lowest walking speed. Between the six difference suits limited differences were found, a two-layered aluminized suit exhibited significant shorter tolerance times in the moderate climate, but no other major significant differences were found for the other climates or workloads. An important characteristic of the overall dataset is the large variability between the subjects. Although the average responses seem suitable to be predicted, the variability in the warmer strain conditions ranged from 20 min up to 60 min. The work load in these encapsulated impermeable suits was also significantly higher than working in normal clothing and higher than predicted by the Pandolf equation. Heart rate showed a very strong correlation to body core temperature and was in many cases the limiting factor. Setting the heart rate maximum at 80% of predicted individual maximum (age based) would have prevented 95% of the cases with excessive heat strain. Monitoring of heart rate under operational conditions would further allow individually optimize working times and help in preventing exertional heat stroke.
AATCC Journal of Research
Ergonomics, 2016
Abstract Range of motion (ROM) can be restricted by wearing stiff and bulky clothing. This is par... more Abstract Range of motion (ROM) can be restricted by wearing stiff and bulky clothing. This is particularly true of firefighter suits that are constructed using fabric layers to provide thermal protection from fire. This study developed an evaluation technique to quantify the loss of mobility associated with wearing firefighters’ protective suits that were deliberately selected to represent similar ergonomic design features. The ROM of 10 firefighters was measured using electro-goniometers attached to their bodies while they wore uniforms and a reference outfit, and performed specific movements. The most restrictive uniform is the Bulky suit that contained additional layers of materials in sleeves and on the knees. The Traditional Suit was more ROM restrictive than Ergonomic. The subjective evaluation of suits supported the objective assessments provided by the electro-goniometers. A 3-D body scanning technique was employed to establish a correlation between the bulkiness of firefighter outfits and subject ROM. Practitioner Summary: This study presents a methodology for measurements of range of motion (ROM) in firefighters wearing personal protective equipment (PPE). Even small differences in designs of PPE may impact firefighters’ ROM, which can be detected by electro-goniometers providing measurements if they are attached along the joint to measure limb angular movement.
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Papers by emiel denhartog