Calculation of Clothing Insulation by Serial and Parallel Methods: Effects on Clothing Choice by IREQ and Thermal Responses in the Cold

A Database of Static Thermal Insulation and Evaporative Resistance Values of Dutch Firefighter Clothing Items and Ensembles

The rescue operations' environment can impair firefighters' performance and increase the risk of injuries, e.g., burns and hyperthermia. The bulk and carried weight of heavy protection contributes to lower physical performance, higher metabolic load and internal body heat production. For recommending optimal protection for the tasks and incident scenarios, knowledge of clothing thermal properties is needed. However, detailed data on firefighter protective clothing systems are not available. The aim of the study was to provide scientific background and a dataset that would allow for validation of thermo-physiological models for task-specific conditions of rescue work. Thermal insulation of 37 single items and their variations and 25 realistic protective clothing ensembles were measured on a thermal manikin. Twelve (12) ensembles that evenly covered the whole insulation range were selected for evaporative resistance testing. The equations for summing up individual item's insulation to ensemble insulation and calculating clothing area factor were derived from the dataset. The database of a firefighter clothing system was created. In addition, the local and regional thermal properties of the clothing ensembles were provided for use in future validation of advanced thermo-physiological models for rescue worker exposure predictions and for designing decision aid tools.

Human physiological responses of exposure to extremely cold environments

Extremely cold events have occurred more frequently in the past few years. People exposed to extremely cold exposure could suffer the threats of human health and safety like cold stress and injury. This study aims to investigate human physiological responses of exposure to extremely cold environments and the moment of temperature step. The experiments of 12 subjects exposed to three different cold exposure conditions (-5 °C, -10 °C, -15 °C) were carried out in a climate chamber. Most critical physiological parameters, including the core temperature, local skin temperature, blood pressure, heart rate, respiration rate and blood oxygen saturation, were measured to evaluate human physiological responses. In the particular short term study, the results show that the local skin temperature and blood pressure are the most significant indexes for evaluating the risk of cold strain in extremely cold environment. The finger temperature is a critical index of hand and finger flexibility, and it will lead to serious injuries and reduced manual performance when exposed to below -5 °C for more than 20 min. The high physiological strain at the very beginning moment of cold exposure can significantly affect the ability to make correct judgment and action, and it is suggested that the personnel adapt for 3 min after entering into the extremely cold environment to stabilize physiological parameters and thus enhancing the safety and occupational performance. The experimental data of this study is also of great significance for the development and validation of thermophysiological models.

Towards a wearable sensor system for continuous occupational cold stress assessment

This study investigated the usefulness of continuous sensor data for improving occupational cold stress assessment. Eleven volunteer male subjects completed a 90-120-min protocol in cold environments, consisting of rest, moderate and hard work. Biomedical data were measured using a smart jacket with integrated temperature, humidity and activity sensors, in addition to a custom-made sensor belt worn around the chest. Other relevant sensor data were measured using commercially available sensors. The study aimed to improve decision support for workers in cold climates, by taking advantage of the information provided by data from the rapidly growing market of wearable sensors. Important findings were that the subjective thermal sensation did not correspond to the measured absolute skin temperature and that large differences were observed in both metabolic energy production and skin temperatures under identical exposure conditions. Temperature, humidity, activity and heart rate were found to be relevant parameters for cold stress assessment, and the locations of the sensors in the prototype jacket were adequate. The study reveals the need for cold stress assessment and indicates that a generalised approached is not sufficient to assess the stress on an individual level.

Foot model for tracking temperature of safety boot insoles: application to different insole materials in firefighter boots

This research is based on the development of a human foot model to study the temperature conditions of a foot bottom surface under extreme external conditions. This foot model is made by combining different manufacturing techniques to enable the simulation of bones and tissues, allowing the placement of sensors on its surface to track the temperature values of different points inside a shoe. These sensors let researchers capture valuable data during a defined period of time, making it possible to compare the features of different safety boots, socks or soles, among others. In this case, it has been applied to compare different plantar insole materials, placed into safety boots on a high-temperature surface.

Validation of standard ASTM F2732 and comparison with ISO 11079 with respect to comfort temperature ratings for cold protective clothing

American standard ASTM F2732 estimates the lowest environmental temperature for thermal comfort for cold weather protective clothing. International standard ISO 11079 serves the same purpose but expresses cold stress in terms of required clothing insulation for a given cold climate. The objective of this study was to validate and compare the temperature ratings using human subject tests at two levels of metabolic rates (2 and 4 MET corresponding to 116.4 and 232.8 W/m(2)). Nine young and healthy male subjects participated in the cold exposure at 3.4 and -30.6 °C. The results showed that both standards predict similar temperature ratings for an intrinsic clothing insulation of 1.89 clo and for 2 MET activity. The predicted temperature rating for 2 MET activity is consistent with test subjects' thermophysiological responses, perceived thermal sensation and thermal comfort. For 4 MET activity, however, the whole body responses were on the cold side, particularly the responses of the extremities. ASTM F2732 is also limited due to its omission and simplification of three climatic variables (air velocity, radiant temperature and relative humidity) and exposure time in the cold which are of practical importance.

WITHDRAWN: Comments on "A laboratory validation study of comfort and limit temperatures of four sleeping bags defined according to EN 13537 (2002)"

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The relationship between environmental temperature and clothing insulation across a year

People adapt to thermal environments, such as the changing seasons, predominantly by controlling the amount of clothing insulation, usually in the form of the clothing that they wear. The aim of this study was to determine the actual daily clothing insulation on sedentary human subjects across the seasons. Thirteen females and seven males participated in experiments from January to December in a thermal chamber. Adjacent months were grouped in pairs to give six environmental conditions: (1) January/February = 5°C; (2) March/April = 14°C; (3) May/June = 25°C; (4) July/August = 29°C; (5) September/October = 23°C; (6) November/December = 8°C. Humidity(45 ± 5%) and air velocity(0.14 ± 0.01 m/s) were constant across all six experimental conditions. Participants put on their own clothing that allowed them to achieve thermal comfort for each air temperature, and sat for 60 min (1Met). The clothing insulation (clo) required by these participants had a significant relationship with air temperature: insulation was reduced as air temperature increased. The range of clothing insulation for each condition was 1.87-3.14 clo at 5°C(Jan/Feb), 1.62-2.63 clo at 14°C(Mar/Apr), 0.87-1.59 clo at 25°C(May/Jun), 0.4-1.01 clo at 29°C(Jul/Aug), 0.92-1.81 clo at 23°C (Sept/Oct), and 2.12-3.09 clo at 8°C(Nov/Dec) for females, and 1.84-2.90 clo at 5°C, 1.52-1.98 clo at 14°C, 1.04-1.23 clo at 25°C, 0.51-1.30 clo at 29°C, 0.82-1.45 clo at 23°C and 1.96-3.53 clo at 8°C for males. The hypothesis was that thermal insulation of free living clothing worn by sedentary Korean people would vary across seasons. For Korean people, a comfortable air temperature with clothing insulation of 1 clo was approximately 27°C. This is greater than the typical comfort temperature for 1 clo. It was also found that women clearly increased their clothing insulation level of their clothing as winter approached but did not decrease it by the same amount when spring came.

Theoretical analysis of three methods for calculating thermal insulation of clothing from thermal manikin

There are three methods for calculating thermal insulation of clothing measured with a thermal manikin, i.e. the global method, the serial method, and the parallel method. Under the condition of homogeneous clothing insulation, these three methods yield the same insulation values. If the local heat flux is uniform over the manikin body, the global and serial methods provide the same insulation value. In most cases, the serial method gives a higher insulation value than the global method. There is a possibility that the insulation value from the serial method is lower than the value from the global method. The serial method always gives higher insulation value than the parallel method. The insulation value from the parallel method is higher or lower than the value from the global method, depending on the relationship between the heat loss distribution and the surface temperatures. Under the circumstance of uniform surface temperature distribution over the manikin body, the global and parallel methods give the same insulation value. If the constant surface temperature mode is used in the manikin test, the parallel method can be used to calculate the thermal insulation of clothing. If the constant heat flux mode is used in the manikin test, the serial method can be used to calculate the thermal insulation of clothing. The global method should be used for calculating thermal insulation of clothing for all manikin control modes, especially for thermal comfort regulation mode. The global method should be chosen by clothing manufacturers for labelling their products. The serial and parallel methods provide more information with respect to the different parts of clothing.

Protection against cold in prehospital care: evaporative heat loss reduction by wet clothing removal or the addition of a vapor barrier--a thermal manikin study

INTRODUCTION

In the prehospital care of a cold and wet person, early application of adequate insulation is of utmost importance to reduce cold stress, limit body core cooling, and prevent deterioration of the patient's condition. Most prehospital guidelines on protection against cold recommend the removal of wet clothing prior to insulation, and some also recommend the use of a waterproof vapor barrier to reduce evaporative heat loss. However, there is little scientific evidence of the effectiveness of these measures.

OBJECTIVE

Using a thermal manikin with wet clothing, this study was conducted to determine the effect of wet clothing removal or the addition of a vapor barrier on thermal insulation and evaporative heat loss using different amounts of insulation in both warm and cold ambient conditions.

METHODS

A thermal manikin dressed in wet clothing was set up in accordance with the European Standard for assessing requirements of sleeping bags, modified for wet heat loss determination, and the climatic chamber was set to -15 degrees Celsius (°C) for cold conditions and +10°C for warm conditions. Three different insulation ensembles, one, two or seven woollen blankets, were chosen to provide different levels of insulation. Five different test conditions were evaluated for all three levels of insulation ensembles: (1) dry underwear; (2) dry underwear with a vapor barrier; (3) wet underwear; (4) wet underwear with a vapor barrier; and (5) no underwear. Dry and wet heat loss and thermal resistance were determined from continuous monitoring of ambient air temperature, manikin surface temperature, heat flux and evaporative mass loss rate.

RESULTS

Independent of insulation thickness or ambient temperature, the removal of wet clothing or the addition of a vapor barrier resulted in a reduction in total heat loss of 19-42%. The absolute heat loss reduction was greater, however, and thus clinically more important in cold environments when little insulation is available. A similar reduction in total heat loss was also achieved by increasing the insulation from one to two blankets or from two to seven blankets.

CONCLUSION

Wet clothing removal or the addition of a vapor barrier effectively reduced evaporative heat loss and might thus be of great importance in prehospital rescue scenarios in cold environments with limited insulation available, such as in mass-casualty situations or during protracted evacuations in harsh conditions.

Age and Workers' Perceptions of Workplace Safety: A Comparative Study

The study examined the relationship between age and I) safety perception; ii) job satisfaction; iii) compliance with safety management policies; and (iv) accident frequency. Participants were Ghanaian industrial workers ( N = 320) categorized into 4 age groups: 19–29 years; 30–39 years; 40–50 years; and 51 years and above. Workplace safety perception was assessed with Hayes, Perander, Smecko, and Trask's (1998) 50-item Work Safety Scale (WSS): a scale that effectively captures the dimensions identified by safety experts to influence perceptions of workplace safety. ANOVA was used to test for differences in the mean scores of the 4 groups. Post Hoc analysis revealed differences of statistical significance between the 2 younger cohorts and the 2 older cohorts. The results indicated a positive association between age and safety perception. Older workers had the best perceptions on safety, indicated the highest level of job satisfaction, were the most compliant with safety procedures, and recorded the lowest accident involvement rate. From a practical perspective, understanding age-related perceptions of workplace safety would benefit management's decisions regarding workers' adaptability, general work effectiveness, accident frequency, implementation of safety management policies, and handling of age-related accident characteristics.