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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
71

Avaliação de dispositivos de proteção individual utilizados em radiologia diagnóstica

SOARES, FERNANDA C.S. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:52:11Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:58:13Z (GMT). No. of bitstreams: 0 / Neste trabalho foram avaliados aventais de proteção e blindagens de ovário de cinco fabricantes segundo as normas NBR / IEC 61331-1 e NBR / IEC 61331-3 de 2004. Para a determinação da espessura equivalente de atenuação foram aplicadas três metodologias diferentes (interpolação linear, modelo de Archer e somatório de exponenciais), uma vez que a norma não indica como este valor deve ser obtido. Além disso, foram estimadas as incertezas associadas a cada método e a influência do número de medições na incerteza combinada. As características de confecção avaliadas foram: documento acompanhante, projeto, materiais, dimensões e marcação da etiqueta. Para esta avaliação foi elaborado um formulário que contemplava todas as exigências da NBR / IEC 61331-3. Os resultados mostraram uma grande diferença entre os valores de espessura equivalente de atenuação declarados e medidos. A comparação dos resultados das três metodologias aplicadas mostrou que há pouca variação entre os valores obtidos e entre as incertezas associadas nas diferentes metodologias. Foi possível observar também que o número de medições não contribui significativamente para o aumento da incerteza nas três metodologias. A metodologia que melhor se adequou à rotina do laboratório foi a metodologia da interpolação linear com cinco medições da taxa de kerma no ar. A discrepância entre os resultados apresentados neste trabalho e as exigências das normas estudadas mostra a necessidade de tornar compulsória a certificação dos dispositivos de proteção, contribuindo assim para o aumento da proteção radiológica do usuário. / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
72

Uso e manuseio do jaleco: uma análise das condutas dos trabalhadores da saúde na prática clínica / Use and handling of white coat: an analysis of the behavior of healthcare workers in clinical practice

Neves, Heliny Carneiro Cunha 15 September 2015 (has links)
Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2016-01-08T11:03:23Z No. of bitstreams: 2 Tese - Heliny Carneiro Cunha Neves - 2015.pdf: 1152827 bytes, checksum: 4bccda1807b733bcca194a438795410f (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2016-01-08T11:05:52Z (GMT) No. of bitstreams: 2 Tese - Heliny Carneiro Cunha Neves - 2015.pdf: 1152827 bytes, checksum: 4bccda1807b733bcca194a438795410f (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2016-01-08T11:05:52Z (GMT). No. of bitstreams: 2 Tese - Heliny Carneiro Cunha Neves - 2015.pdf: 1152827 bytes, checksum: 4bccda1807b733bcca194a438795410f (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2015-09-15 / Inappropriate behaviors of healthcare workers about the use and the handling lab coat represent a risk to the patient and the professional, family and community. The recommendations in this area are guided on limited evidences and the specific norms for the standardization of practices for use and handling is fragile. OBJECTIVE: To analyze the use and handling of lab coats by healthcare workers. METHODS: Cross-sectional, observational and analytical study conducted with 103 healthcare workers in a public teaching hospital, located in the Center-West of Brazil. The characteristics of the lab coats, the data regarding the transport and the handwashing practice before wearing and after removing the lab coat were observed at the arrival timing and exit of the unit and registered in check list. The use of clothes and larger contact areas with surfaces and patients were observed at the time of procedures execution. Sociodemographic and occupational data and the worker's conduct about lab coat handling were collected through interview after the observation period of each professional. To estimate the factors associated with misconduct of healthcare workers as hand hygiene, transportation and exchange frequency of lab coat the univariate analysis was performed. Then variables with p <0.10 were included in the Poisson regression model. The chi-square test was used to verify the differences between the ratios and p values <0.05 were considered statistically significant. RESULTS: The workers used the lab coat and the gown to the different clinical situations observed, without clarity when to use each clothes. Fists and abdominal region of lab coats and gown were areas that had higher patient contact and higher environmental surfaces contact. Workers had inappropriate handling about the lab coats transport, exchange frequency, washing process and hand hygiene. Were predictors for misconduct about the exchange frequency of lab coat, to be physicians and other healthcare workers male, with shorter professional practice and reporting inadequate practice to transport lab coats. Were associated with inadequate practices of lab coats transport, have misconduct about the exchange frequency and the physicians workers. CONCLUSIONS: The conduct of workers using their own lab coat like a protective equipment and transports to process at home are inadequate and can endanger the health and safety of workers, their families and patients. These findings show that the lab coat worker must not be used as personal protective equipment in clinical practice. / Comportamentos inadequados dos trabalhadores da saúde em relação ao uso e manuseio do jaleco representam um risco tanto para o paciente como para o próprio profissional, familiares e comunidade. As recomendações nessa área são pautadas em evidências limitadas e a normatização específica para a padronização das práticas para o seu uso e manuseio é frágil. OBJETIVO: Analisar o uso e manuseio do jaleco pelos trabalhadores da área da saúde. MÉTODOS: Estudo transversal, observacional, analítico, realizado com 103 trabalhadores da saúde de um hospital público, de ensino, situado na região Centro-Oeste do Brasil. As características dos jalecos, os dados em relação ao transporte e a prática de higienização das mãos antes de vestir e após retirar o jaleco foram observados no momento da entrada e da saída da unidade e registrados em check list. O uso das vestimentas e os locais de maior contato com superfícies e com os pacientes foram observados no momento da execução dos procedimentos. Os dados sociodemográficos, ocupacionais e as condutas do trabalhador sobre o manuseio do jaleco foram coletados por meio de entrevista após o período de observação de cada profissional. Para estimar os fatores associados às condutas inadequadas dos trabalhadores quanto à higienização das mãos, transporte e frequência de troca do jaleco foi realizada análise univariada. Em seguida, variáveis com p < 0,10 foram incluídas no modelo de Regressão de Poisson. O teste de qui-quadrado foi utilizado para verificar as diferenças entre as proporções e valores de p < 0,05 foram considerados estatisticamente significantes. RESULTADOS: Os trabalhadores utilizaram tanto o jaleco quanto o avental para as diferentes situações clínicas observadas, sem muita clareza de quando usar cada vestimenta. Os punhos e a região abdominal dos jalecos e dos aventais foram as áreas que apresentaram maior contato com o paciente e com as superfícies ambientais. Os trabalhadores apresentaram manuseio inadequado quanto ao transporte do jaleco, frequência de troca, processo de lavagem e higienização das mãos. Foram preditores para a conduta inadequada em relação à frequência de troca do jaleco ser trabalhador da categoria médica e outros trabalhadores da saúde, do sexo masculino, com menor tempo de atuação profissional e que relataram prática inadequada em relação ao transporte do jaleco. Foram associadas às práticas inadequadas do transporte do jaleco, ter conduta inadequada em relação à frequência de troca e os trabalhadores da categoria médica. CONCLUSÕES: As condutas dos trabalhadores que utilizam o próprio jaleco como equipamento de proteção e o transporta para processar no domicílio são inadequadas e podem colocar em risco a saúde e segurança do trabalhador, seus familiares e dos pacientes. Esses achados evidenciam que o jaleco próprio do trabalhador não deve ser utilizado como equipamento de proteção individual na prática clínica.
73

Occupational exposure to electromagnetic fields in the heavy engineering CO2 welding industry in the Mangaung Metropolitan municipality

Raphela, Selepeng France January 2013 (has links)
Thesis (D. Tech. (Environmental Health)) -- Central University of technology, Free State, 2013 / Some epidemiological studies suggest that exposure to high levels of electromagnetic fields (EMFs) may be linked with the development of adverse health effects. However there is still controversy on this matter. Due to rapid technological growth in the modern society, employees in the welding and electrical industries are highly exposed to electromagnetic fields and may be at a high risk for developing occupational diseases. The health effects which may result from exposure to electromagnetic fields are related to the strength and frequency of the fields. This study was conducted to (i) assess the exposure levels to EMFs in the welding industry, (ii) determine the possible health risks associated with exposure levels, and (iii) develop a health and safety model to guide the industry on how to reduce exposure to EMFs. The study was conducted in one mega welding company in the Mangaung Metropolitan Municipality. Welders, fitters and office workers (88 in total) gave consent to participate in the study and completed questionnaires (ethical clearance attached). Measurements of extremely low frequency EMFs were taken in workshop A, workshop B and working offices. Measurements for magnetic fields were taken at distances of 1, 2 and 3 meters (m) from the EMFs sources. The exposure levels of magnetic fields were very high in the workshops, with welders and fitters exposed to about 7.6 microtesla (μT). Electric fields were relatively low in all workstations. Participants in the study were experiencing symptoms of ill health such as headaches, sleep disorders, fatigue and distress. The symptoms reported by the workers were similar in the both groups (exposed and control). There is no clear relationship between recorded exposure levels and the development of the reported symptoms. The health and safety model was developed to guide the industry to reduce exposure to electromagnetic fields. The model describes the implementation of engineering and administrative control measures in an effort to reduce exposure to EMFs. The model also highlights the importance of wearing personal protective equipment to shield against EMFs amongst others. This study suggests that occupational exposure to high levels of extremely low frequency EMFs may increase the risk for development of chronic diseases such as leukaemia, brain and breast cancer and other diseases among highly exposed employees. Implementation of safety measures is necessary to reduce exposure to EMFs.
74

Avaliação de dispositivos de proteção individual utilizados em radiologia diagnóstica / Evaluation of personal protective devices used in diagnostic radiology

Soares, Fernanda Cristina Salvador 09 October 2006 (has links)
Neste trabalho foram avaliados aventais de proteção e blindagens de ovário de cinco fabricantes segundo as normas NBR / IEC 61331-1 e NBR / IEC 61331-3 de 2004. Para a determinação da espessura equivalente de atenuação foram aplicadas três metodologias diferentes (interpolação linear, modelo de Archer e somatório de exponenciais), uma vez que a norma não indica como este valor deve ser obtido. Além disso, foram estimadas as incertezas associadas a cada método e a influência do número de medições na incerteza combinada. As características de confecção avaliadas foram: documento acompanhante, projeto, materiais, dimensões e marcação da etiqueta. Para esta avaliação foi elaborado um formulário que contemplava todas as exigências da NBR / IEC 61331-3. Os resultados mostraram uma grande diferença entre os valores de espessura equivalente de atenuação declarados e medidos. A comparação dos resultados das três metodologias aplicadas mostrou que há pouca variação entre os valores obtidos e entre as incertezas associadas nas diferentes metodologias. Foi possível observar também que o número de medições não contribui significativamente para o aumento da incerteza nas três metodologias. A metodologia que melhor se adequou à rotina do laboratório foi a metodologia da interpolação linear com cinco medições da taxa de kerma no ar. A discrepância entre os resultados apresentados neste trabalho e as exigências das normas estudadas mostra a necessidade de tornar compulsória a certificação dos dispositivos de proteção, contribuindo assim para o aumento da proteção radiológica do usuário. / In this work protective devices of five manufacturers were evaluated according to the NBR/IEC 61331-1 and NBR/IEC 61331-3 standards. Three different methodologies (linear interpolation, Archer model and sum of exponentials) were applied for the determination of the attenuation equivalent, since the standard does not indicate how it must be determined. Moreover, the uncertainties associated to each method, and the influence of the number of measurements in the combined uncertainty were estimated. The evaluated manufacture characteristics were: accompanying document, design, materials, dimensions and label marking. For this evaluation a check list about the requirements of the NBR/IEC 61331-3 standard was elaborated. The results showed a great difference between nominal and measured attenuation equivalent values. The comparison of the results using the three methodologies showed small variations among the obtained values and among the associated uncertainties in the different methodologies. It was possible to observe that the number of measurements does not contribute significantly for the increase of the uncertainty in all three methodologies. The best methodology for the laboratory routine is the linear interpolation methodology, with five measurements for each air kerma rate value. The discrepancy between the results obtained in this work and the requirements of the applied standards show the need to adopt a compulsory certification process for protective devices, thus contributing for the increase of the radiation protection of the users.
75

Avaliação de dispositivos de proteção individual utilizados em radiologia diagnóstica / Evaluation of personal protective devices used in diagnostic radiology

Fernanda Cristina Salvador Soares 09 October 2006 (has links)
Neste trabalho foram avaliados aventais de proteção e blindagens de ovário de cinco fabricantes segundo as normas NBR / IEC 61331-1 e NBR / IEC 61331-3 de 2004. Para a determinação da espessura equivalente de atenuação foram aplicadas três metodologias diferentes (interpolação linear, modelo de Archer e somatório de exponenciais), uma vez que a norma não indica como este valor deve ser obtido. Além disso, foram estimadas as incertezas associadas a cada método e a influência do número de medições na incerteza combinada. As características de confecção avaliadas foram: documento acompanhante, projeto, materiais, dimensões e marcação da etiqueta. Para esta avaliação foi elaborado um formulário que contemplava todas as exigências da NBR / IEC 61331-3. Os resultados mostraram uma grande diferença entre os valores de espessura equivalente de atenuação declarados e medidos. A comparação dos resultados das três metodologias aplicadas mostrou que há pouca variação entre os valores obtidos e entre as incertezas associadas nas diferentes metodologias. Foi possível observar também que o número de medições não contribui significativamente para o aumento da incerteza nas três metodologias. A metodologia que melhor se adequou à rotina do laboratório foi a metodologia da interpolação linear com cinco medições da taxa de kerma no ar. A discrepância entre os resultados apresentados neste trabalho e as exigências das normas estudadas mostra a necessidade de tornar compulsória a certificação dos dispositivos de proteção, contribuindo assim para o aumento da proteção radiológica do usuário. / In this work protective devices of five manufacturers were evaluated according to the NBR/IEC 61331-1 and NBR/IEC 61331-3 standards. Three different methodologies (linear interpolation, Archer model and sum of exponentials) were applied for the determination of the attenuation equivalent, since the standard does not indicate how it must be determined. Moreover, the uncertainties associated to each method, and the influence of the number of measurements in the combined uncertainty were estimated. The evaluated manufacture characteristics were: accompanying document, design, materials, dimensions and label marking. For this evaluation a check list about the requirements of the NBR/IEC 61331-3 standard was elaborated. The results showed a great difference between nominal and measured attenuation equivalent values. The comparison of the results using the three methodologies showed small variations among the obtained values and among the associated uncertainties in the different methodologies. It was possible to observe that the number of measurements does not contribute significantly for the increase of the uncertainty in all three methodologies. The best methodology for the laboratory routine is the linear interpolation methodology, with five measurements for each air kerma rate value. The discrepancy between the results obtained in this work and the requirements of the applied standards show the need to adopt a compulsory certification process for protective devices, thus contributing for the increase of the radiation protection of the users.
76

Development of an Instrumented Dynamic Mannequin Test to Rate the Protection Provided by Protective Clothing

Sipe, Joel Edwards 03 May 2004 (has links)
A dynamic mannequin testing facility has been constructed to test the thermal protective properties of Navy uniforms and protective clothing. The existing facility consists of a traversing mannequin mechanism that passes through a fire that has been spatially characterized by temperature and heat flux measurements. The fire is provided by 8 propane sand burners in a modified ISO 9705 room. The current project is a continuation of work done by WPI Students over the last 5 years. A copper disk surface heat flux transducer has been designed and calibrated in the WPI Cone Calorimeter. The mannequin has been instrumented with 40 of these transducers for the acquisition of heat flux data during fire exposures. Heat Flux data was collected with the bare mannequin and through protective clothing for a range of exposure times. A finite difference method approach is used to model the skins temperature response at the epidermis-dermis interface. This temperature is used to predict 1st and 2nd degree skin burns using Henrique's burn damage integral. The percent total body area (%TBA) affected by burns can be calculated by this method. The facility is now capable of providing comparative data on the relative thermal protection provided by different clothing.
77

Evaluation of New Test Methods for Fire Fighting Clothing

Gagnon, Brian D. 18 April 2000 (has links)
Despite advancements in the development of synthetic fibers and materials that provide better insulation, fire ground burn injuries remain a significant issue. The current test methods for fire fighting clothing were investigated to determine their adequacy in evaluating the actual performance of clothing materials. This investigation uncovered several potential problems with the current test methods. A series of new, small scale, tests were used to evaluate the shortcomings of the current test methods and develop possible improvements. A small test apparatus, designed and donated by Ktech Corporation, was used to measure the thermal properties (thermal conductivity and volumetric heat capacity) of a series of fire fighting clothing materials. The thermal properties were estimated for single fabric layers, as well as ensembles, with various levels of moisture added to simulate actual end use conditions. In addition, a skin simulant sensor was used to assess the time to 2nd degree burn for exposures similar to those required in current standards for fire fighting clothing. A one dimensional heat conduction model was developed to predict the time to 2nd degree burn for the skin simulant sensor protected with outer shell materials that may be used as wildland fire fighting clothing, using the thermal property data obtained from earlier tests. An alternative method was developed to calculate the time to 2nd degree burn for ensembles evaluated with the new skin simulant sensor. The predictions for the time to 2nd degree burn obtained from the new skin simulant sensor were compared against results obtained using the sensor specified in the current test methods. The predictions for the skin simulant sensor were consistently shorter than those from the current test sensor. The current test sensor predictions for the time to 2nd degree burn were nominally 40% to 50% higher than the predictions from the skin simulant sensor during the evaluations of outer shell materials.
78

Quantification des causes des accidents de deux / trois-roues motorisés et de leurs conséquences corporelle (approche épidémiologique)s / Quantification of causes of motorized two/three-wheelers accidents and injury consequences (epidemiological approach)

Wu, Dan 02 October 2018 (has links)
Contexte : les deux-roues motorisés (2RM) sont en forte évolution et la vulnérabilité de leurs usagers est de plus en plus manifeste. En 2013, dans le monde, les usagers de 2RM ont compté pour 23 % de la mortalité routière, devant les piétons (22 %). Dans ce contexte, la sécurité des usagers de 2RM est devenue une préoccupation sérieuse dans la plupart des pays. Contrairement à beaucoup de problèmes de santé publique, les principaux facteurs de l'insécurité routière en 2RM sont connus. L'enjeu d'aujourd'hui est surtout de quantifier leur effet sur la survenue d'accidents et d'évaluer les effets des quelques dispositifs de protection disponibles. Les objectifs de cette thèse sont de mieux connaitre les problèmes d'interaction entre les conducteurs de 2RM et les automobilistes selon différentes situations accidentelles (en particulier en intersection), de quantifier les effets des facteurs à l'origine de la survenue des accidents issus de la perte de contrôle du 2RM, et de mesurer l'efficacité des dispositifs de protection portés par les usagers de 2RM (casque intégral, blouson de moto, pantalon de moto, gants, bottes ou chaussures montantes et protection dorsale). Données : la réalisation des objectifs de la thèse s'appuie sur les données du projet VOIESUR, les données du Registre des accidents de la circulation du Rhône et les données recueillies au moyen d'une enquête postale réalisée auprès de 7 148 usagers de 2RM accidentés entre 2010 et 2014 identifiés par le Registre du Rhône. Résultats : Le problème de détectabilité des motos au niveau des intersections est confirmé. Dans la même situation d'interaction entre deux véhicules en intersection, un automobiliste a plus de difficulté à détecter une moto qu'à détecter un véhicule léger. Les facteurs suivants sont associés à la survenue des accidents de type perte de contrôle : alcool, type de moto, jour de l'accident, sinuosité de la route, adhérence de la route et vitesse. Nous soulignons le fait qu'une mauvaise adhérence de la route augmente considérablement le risque de perte de contrôle, en particulier lorsque la dégradation de l'adhérence est inattendue pour les motocyclistes en raison de la présence de gravillons, de corps gras, de nids de poule, etc. sur la route. En cas d'accident, les vêtements dédiés à la moto protègent les usagers des blessures. Ils sont efficaces pour éviter les dermabrasions et les plaies cutanées, mais ne semblent pas protéger des blessures plus graves telles que fracture, luxation ou entorse, sauf pour les bottes ou chaussures montantes qui réduisent le risque de fracture de la cheville ou du pied. Concernant les plaques dorsales, aucune efficacité n'a été montrée. Les casques intégraux protègent mieux le visage de l'usager du 2RM comparés aux non-intégraux, alors qu'aucune différence de protection du crâne ou du cerveau n'est mise en évidence entre les deux types de casques. Conclusion : Nos résultats mettent en évidence le problème de détectabilité d'un 2RM par les automobilistes en intersection et l'importance de l'état de la chaussée dans les accidents associés à une perte de contrôle du 2RM par son conducteur. Il est fortement recommandé pour les automobilistes de bien faire attention aux véhicules prioritaires venant de la gauche ou d'en face avant de tourner à gauche, particulièrement aux 2RM venant d'en face. L'amélioration de l'état de la chaussée et une signalisation adaptée représentent aussi un enjeu fort pour la sécurité des usagers de 2RM. Nos résultats soutiennent la recommandation faite par les organismes de sécurité routière du port plus systématique des équipements vestimentaires chez les usagers de 2RM. Enfin, nos résultats encouragent l'utilisation d'un casque intégral chez les usagers de 2RM afin de mieux protéger le visage / Background: Motorized two-wheelers (MTW) are evolving rapidly and the vulnerability of their users is becoming more obvious. MTW users were the most vulnerable road users, accounting for 23 % of all road traffic fatalities worldwide in 2013, in front of pedestrians (22 %). In this context, the safety of MTW users has become a serious concern in most countries. In contrast to many public health problems, the main factors of MTW road safety have been identified. The issue today is to quantify their effects on the occurrence of accidents and to measure the effects of protective devices. The present thesis aims to better understand the interaction problems between MTW drivers and automobilists according to different accident configurations (in particular at intersection), to identify and assess the effect of critical factors on the risk of MTW loss-of-control crashes, and to measure the effectiveness of protective clothing (motorcycle jacket, trousers, gloves, knee-high or ankle boots, back protection) for MTW users. Data: This study used MTW accident data collected in a French project VOIESUR, injury data from the Rhône Registry, plus data collected by means of a postal survey which was conducted among 7148 MTW riders injured between 2010 and 2014 and identified in the Rhône Registry. Results: We confirmed the problem of motorcycle detection for other road users. In the similar conditions, the motorists have more difficulty to detect a motorcycle than a car oncoming, in particular at intersections. The following factors are associated with the occurrence of motorcycle loss-of-control accidents: alcohol use, motorcycle type, weekend vs. weekday, road alignment, road adhesion and traveling speed. We emphasize that poor road adhesion significantly increases the risk of losing control, especially when deteriorated road adhesion is encountered unexpectedly, due to the presence of loose gravel, ice, oil, potholes, etc. on the roadway. In case of accident, motorcycle clothing protects users from injury. It can protect riders against injuries such as dermabrasion and laceration, but not against more serious injuries, such as fracture and sprain, except for boots, which reduce foot-and-ankle fracture risk. No effect of dorsal protectors was shown. Full-face helmets provide significantly greater protection against facial injury than do other helmets. However, no significant difference of protection against skull or brain injury is found between the two types of helmets. Conclusion: Our results highlight the problem of MTW detection for motorists at intersections and the important role of road conditions in the occurrence of accidents resulting from loss of control of MTW. It is recommended for motorists to pay extra attention to priority vehicles oncoming from their left or the opposite direction, before turning left at an intersection, especially to MTW. Regular road maintenance and immediate installment of appropriate warning signs concerning road deterioration are also highly recommended in consideration of MTW safety. Finally, our results support road safety organizations’ recommendation that protective clothing be worn: this should be more systematic for MTW users, the same for the use of full-face helmets
79

Apparent Total Evaporative Resistance Values From Human Trials Over a Range of Metabolic and Heat Stress Levels

Dooris, Matthew David 01 January 2011 (has links)
Failure to maintain thermal equilibrium can cause uncontrollable increases in body core temperature beyond critical upper limits. In selecting clothing, consideration must be given to the heat transfer properties of clothing that may restrict the cooling capacity of the human body under heat stress conditions, most importantly, apparent total evaporative resistance (Re,T,a). This study calculated and compared Re,T,a for five clothing ensembles under varying heat stress conditions, including three relative humidity (RH) levels and three stages of heat stress to determine if Re,T,a values varied or remained the same with changes in heat stress conditions. A four-way mixed model analysis of variance demonstrated significant differences for estimated Re,T,a values among ensembles, RH levels, heat stress stages, and interactions among ensembles and RH levels and ensembles and heat stress stages (p < 0.0001). No significant interaction among RH levels and heat stress stages was found (p = 0.67). A Tukey's Honestly Significant Difference multiple comparison test was used to identify where significant differences occurred (p < 0.05). The results of the study indicated that Re,T,a values do change with RH levels and stages of heat stress and that the theoretical framework for explaining heat-exchange in hot environments is not yet well-established. Also confirmed was the dominance of the convection pathway over the diffusion pathway in hot environments.
80

Heat Stress Evaluation of Protective Clothing Ensembles

Pease, Amanda Lee 01 January 2010 (has links)
Clothing directly affects the level of heat stress exposure. Useful measures to express the thermal characteristics are WBGT (wet bulb globe temperature) clothing adjustment factor (CAF) or apparent total evaporative resistance (Re,T,a). The CAF is assigned through laboratory wear trials following a heat stress protocol in which the air temperature and humidity are progressively increased until the participant clearly loses the ability to maintain thermal equilibrium. The critical condition is the point of thermal transition and from these conditions both the CAF and Re,T,a are computed. The first objective of this study is to compare the thermal characteristics of a coverall made from a prototype fabric to work clothes and a commercial limited-use coverall using CAF and Re,T,a. A second objective is to demonstrate that the Re,T,a of work clothes is the same for progressive or steady-state heat stress protocols. Five participants (4 men and 1 woman) walked on a treadmill at 1.25 m/s at an average metabolic rate of 175 W/m2. Each participant completed at least one progressive heat stress protocols in work clothes, Tyvek® 1422A coveralls [Tyvek® is a registered trademark of DuPont], and a developmental nonwoven polyolefin prototype ensemble provided by DuPont. In addition, four participants completed steady-state protocol in work clothes. Participants did not complete an acclimation period prior to the trials and each trail was separated by at least 40 hours. There are no within participant differences in metabolic rate among ensembles and protocols. There are no differences between the critical WBGT in the current participants and previously acclimatized participants from other studies suggesting that the participants responded as if they were acclimatized. Based on a mixed effects model, there are significant differences between work clothes and Tyvek® 1422A for Re,T,a (0.0103 and 0.0141 m2/W kPa, respectively) and critical WBGT. The CAF for Tyvek is 2.3 °C-WBGT. For the DuPont prototype ensemble, the apparent total evaporative resistance is 0.013 m2kPa/W and the CAF is 0.5 °C. The prototype ensemble shows no difference from work clothes or Tyvek® 1422A in critical WBGT and no difference from work clothes in Re,T,a. Overall, the prototype coveralls exhibited thermal characteristics that would have a lower level of heat stress than the Tyvek 1422A and not significantly different from work clothes. The values for Re,T,a for work clothes were not different between the steady state and progressive protocols. The steady-state protocol near the critical condition can be used for determination of Re,T,a. This opens up the possibility of estimating Re,T,a from studies that do not use the progressive protocol.

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