Nazia Nawaz

Thermal comfort properties of knitted fabrics suitable for skin layer of protective clothing worn in extreme hot conditions

Key words: Physiological comfort, knitted fabrics, protective clothing Abstract. Thermal comfort of clothing is associated with the thermal balance between human body and the environment, and also a balance between the body heat production and the heat loss. During work activities performed in extreme hot conditions, the body produces substantial amount of heat energy which leads to raised body temperature. As a result the body perspires in liquid and vapour form to reduce the increased temperature. When this perspiration is transmitted to the atmosphere, the body temperature reduces. Thus the garments worn next to skin should allow the perspiration and heat to easily pass through them; otherwise the result will be a significant discomfort of the persons working in extreme hot conditions. Therefore, thermal properties and water vapour permeability of the fabrics used for the next-to-skin layer of protective clothing are very important for the maintenance of physiological comfort of workers. In the present study physical parameters, air permeability, porosity, thermal and water vapour permeability of six commercially available knitted fabrics of different fibre blends, different and knitted structures suitable for skin layer garments of protective clothing worn in extreme hot conditions were evaluated. The influences of fabric physical parameters, and optical porosity on thermal conductivity and water vapour permeability of fabrics were determined and correlation coefficients were calculated between these variables.

Towards sustainable and safe apparel cleaning methods: A review

Perchloroethylene (PERC) is a compound commonly used as a solvent in dry cleaning, despite its severe health and environmental impacts. In recent times chemicals such as hydrocarbons, GreenEarth(®), acetal and liquid carbon dioxide have emerged as less damaging substitutes for PERC, and an even more sustainable water-based wet cleaning process has been developed. We employed a systematic review approach to provide a comprehensive overview of the existing research evidence in the area of sustainable and safe apparel cleaning methods and care. Our review describes traditional professional dry cleaning methods, as well as those that utilise solvents other than PERC, and their ecological attributes. In addition, the new professional wet cleaning process is discussed. Finally, we address the health hazards of the various solvents used in dry cleaning and state-of-the-art solvent residue trace analysis techniques.

Materials and Engineering Design for Human Performance and Protection in Extreme Hot Conditions

The level of protective material performance attributes are well defined and highly regulated, however the attributes related to the thermo physiological comfort of materials are not. In this chapter, the application of new materials to firefighting protective clothing systems used in extreme heat is addressed, with a focus on thermo physiological comfort. The new generation of protective textile materials and their structures are evaluated through use of both objective laboratory testing and mathematical modeling methods. In addition, 3D body imaging technology is utilized to demonstrate a method of assessing the fit of protective garments and its potential impact on the thermal status of the wearer. The proposed engineering approach could be used in other areas where the balance between clothing performance and wear comfort is critical, e.g. sport, work wear etc.

Sleep environments and sleep physiology: A review

Sleep loss impairs task performance and post-physical activity recovery, cognitive performance and mood, heightens fatigue and decreases vigour; poor sleep quality impairs decision-making, the speed and accuracy of task performance, and post-exercise recovery. Sleep time and quality are affected by age, psychological and physiological conditions, culture and environmental factors. Skin temperature, rapid temperature change and sweating during sleep can significantly reduce sleep quality. Hence, the thermal properties of bedding and sleepwear, both in steady-state and transient ambient temperature conditions, are logically important factors. Research to date on sleeping thermal microclimates and their effect on sleep quality is scarce. This present review covers the fundamental elements of human sleep, highlighting physically active people, such as athletes, and the influence of sleepwear and bedding on sleep thermal microclimates, as well as the research methods that have been and could be used in this field. This review identifies opportunity for future research direction and approaches to understanding thermal environments that may support better human sleep.

Firefighters’ protective jackets: Fit to female form and its effects on attributes relevant to thermal comfort

Abstract Often male and female workers wear protective garments of identical construction and style, with females typically wearing small-sized men’s garments. Consequently, the air spaces under garments worn by male and female wearers can substantially differ in size and distribution affecting the physiological comfort of firefighters’ protective clothing. The present study was designed to investigate the effects of varying dimensions and distributions of air spaces in the next-to-skin microclimate under firefighters’ protective jackets on attributes relevant to the thermal comfort of wearer, not only in relation to garment construction and fit, but also to human body geometry using 3D body scanning. Analysis of 20 scans demonstrated that jackets of the same size and construction create larger air spaces under them worn on a female as opposed to on a male body form. Both thermal and vapor resistance of clothing were affected significantly by the volume of trapped air.

Durability of vapor-permeable waterproof textile materials used in sailing protective apparel:

Vapor-permeable waterproof textiles (VPWTs) are used in sailing apparel to protect wearers from weather and water exposure. They must also withstand knocks and abrasion. Failure of fabric waterproofing results in water intrusion, reduced thermal protection and potentially hypothermia. There are no standard methods for testing the waterproof durability of fabrics in these conditions. To evaluate waterproofing durability, we simulated high levels of wear on leading commercially available VPWT assemblies through mechanical treatment in wet conditions. To compare fabrics on multiple performance characteristics, we developed a Total Durability Penalty index associated with leaks and ruptures, weighted by failure pressure. The experiment revealed significant differences in VPWT deterioration under mechanical treatment. We determined that the mass per unit area and thickness of VPWT fabrics are positively correlated with pressure at leakage; that rupture is significantly and negatively associated with the mass per unit area and thickness of the inner and outer layers of fabric; and leakage pressure is positively correlated with the same parameters. These results show that it is important to consider wear conditions when assessing the long-term performance attributes of protective clothing assemblies.

The development of an objective method for evaluating transient sleeping environments

Poor sleep is the key sleep attribute that affects the overall recuperative quality of the sleep state [1]. A common approach in human sleep testing is to use subjects in an environmental chamber [2-4]. One of the significant limitations of this testing is its subjectivity and the small number of subjects [5]. The use of thermal manikins to measure thermal and vapour resistance is a standard method adopted for assessment of sleeping bags and has also been used to measure these attributes of a range of bedding systems, as well as different sleepwear [6].

Medical protective clothing

A broad overview is presented of current medical clothing with specific focus on surgical gowns. Along with the protective function of the surgical clothing, its performance attributes relevant to the thermophysiological and ergonomic comfort of the wearers are discussed. Types of materials used in surgical gowns are addressed including fibres, yarns, fabric constructions used, other materials such as membranes, and additional treatments including coatings and functional finishes. Limitations of current surgical gowns are investigated where comprehensive testing and analysis of comprising materials are carried out, along with thermal manikin testing of the experimental surgical gowns.

Investigation into fit, distribution and size of air gaps in fire-fighter jackets to female body form

The fit of the garment and the resultant air gap distribution and size between the human skin and the inner surface of clothing is one of key factors in the physiological comfort level of firefighters’ protective clothing since the heat loss efficiency through protective clothing is in part affected by the size of air gaps. The size and distribution of air gaps between the body and the garment worn not only depend on the construction and style of the garment but also on body shape of the wearer. Often the same construction and style of garments are worn by male and female workers where the choice of the protective clothing for females is limited to a smaller size of man’s garments only. Thus the air gap between the clothing and the body of a female wearer will therefore have a substantially different size and distribution to that between the clothing and the body of a male wearer. This would not only impact the physiological comfort of the garment ensemble worn but most importantly and most likely its protective and safety attributes as well. For the objective laboratory testing of physiological and protective properties of firefighters’ ensembles thermal manikins are often used. In this study 3D body scanning technology was used to evaluate the fit of the selected fire-fighter’s jackets to both male and female thermal manikin form. The size and distribution of air gaps between the manikin’s male and female body form and the protective jacket were determined, analysed and compared. Thermal manikin “Newton” in male and female form was used in this study where the manikin was scanned nude in male and female form and then scanned wearing the fire-fighters’ protective jacket in two different sizes in both forms. The 3D body scanning data generated in the form of 3D point clouds was analysed to investigate the fit of fire-fighters’ protective jackets to male and female forms and to quantify the air gap size and distribution. It was concluded that the female body geometry leads to more trapped air between the body and the garment worn than the male form, resulting in larger trapped air volume while using the same size, design and construction for both.