Threshold values for the Botsbali: A field study of occupational heat

Abstract

A Botsbali (BB) and an electronic instrument for measuring wet-bulb globe temperature (WBGT) were used to measure the climatic conditions of 30 different work stations in two industrial plants. Measurements were taken twice daily over a 1-year period for a total of 13489 observations. The field study substantiated several desirable features of the BB relating to its size, ruggedness and ease of use. A major advantage concerns the ability to locate the BB near the worker and thus obtain an accurate evaluation of the working environment. During the course of data collection it was observed that rapid water loss which required frequent refilling represented the main disadvantage of the BB. The relationship in degrees Celsius between the BB and WBGT was found with a very high correlation coefficient (R — 0-956) to be WBGT=1·01BB + 2·6. Permissible heat exposure threshold limit values (TLV) in Botsbali units which are equivalent to the TLV recommended by ACGIH (1973) have been developed.