Proposta de Complementação do Método de Avaliação da Exposição Ocupacional ao Calor: estudo de caso da atividade de manutenção de linhas energizadas

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

This thesis had the objective of proposing a complementation, with proactive character, to method and procedures of evaluation concerning occupational exposure to heat predicted in the norms NR-15/1978 and NHO 06/2002, respectively. The electricians of the maintenance team of energized lines at potential, in tension of 69 kV, from Companhia Energética de Alagoas (CEAL) composed the group of workers monitored. The main objective was achieved by measuring climate variables (dry bulb temperature, natural wet bulb temperature, globe temperature and air speed), calculating Wet Bulb Globe Temperature (WBGT), estimating personal variables (metabolism rate and thermal isolation of clothing being used at the time of work development), investigating weight loss rate caused by work accomplishment and evaluating through Norm ISO 7933/89. Besides measures, it was made a comparison between different norms (ISO 7243/89; ISO 7933/89; ISO 8996/90; ISO 7730/94; ISO 9920/95) and recommendations (ABHO/98) in order to fill any gaps still remaining in Brazilian norms that rule the subject. One of the main assumptions proved through the evaluations is related to the significant water loss the worker is submitted every working hour, when work accomplishment demands the use of special protective clothing. When water loss exceeds the limits specified in the Norm ISO 7933/89, it is reasonable to conclude that physiological consequences harmful to workers health may occur. Considering that specific approach, Brazilian legal documents fail. From the working regimes specified in NR-15/1978, the one that admits the work may be performed continuously shows the most agreeable conditions in relation to insalubrity. In one of the working situations examined simply with the use of WBGT, the working regime defined was continuous. However, when based on Norm ISO 7933/89, that same working situation demands that work execution should be interrupted after approximately 30 (thirty) minutes from the beginning, as a way of limiting heat accumulation in the body. For the latter protection requirement may be considered by NR-15/1978, it is necessary that WBGT index moves from 26,7 C, value that defines the work is likely to be executed continuously, at least to 28,1 C, which is the low limit of the range that defines a pause after 30 (thirty) minutes from the very beginning of work execution. As the difference between the above-mentioned WBGTs is 1,4 C, this is the value that should be added to WBGT index acquired, as a way of compensating the effects produced by the clothing. Besides the pauses provided, another significant result of the evaluation according to Norm ISO 7933/89 is time limitation of exposure due to water loss. The maximum of a days work for all the situations investigated was stipulated in 300 (three hundred) minutes (five hours). The results of the research should be understood as restricted to climate and personal conditions described in the present paper. Yet, they may serve as a demarcation in order to specify proper conditions of execution of labor activities in situations distinct from the ones examined.

ASSUNTO(S)

vestimenta especial de proteção engenharia de producao perda de água water loss manutenção em linhas energizadas estresse térmico thermal stress maintenance in energized lines protection special clothing

ACESSO AO ARTIGO

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