Citation

Bernard TE, Hanna WM. Int. J. Ind. Ergonomics 1988; 3(2): 103-113.

Copyright

(Copyright © 1988, Elsevier Publishing)

DOI

unavailable

PMID

unavailable

Abstract

A computer simulation was used to investigate environmental effects on Wet Bulb Globe Temperature (WBGT) and to compare WBGT to Heat Stress Index (HSI). Constant values of WBGT (isometrics) were straight lines on a psychrometric chart with a slope of -1.17 mmHg/dgC. The intercept on the dry bulb axis (zero water vapor pressure) changed with WBGT value, air velocity (v), and mean wall temperature expressed as an increment above air temperature ([Delta]Tw); there was also an interaction between v and [Delta]Tw on changes in intercept. For a given target value of WBGT, HSI changed with environmental conditions, especially with v. Using effective air velocity (adding a component of air movement associated with activity) reduced much of the variation in HSI. Comparisons between WBGT and HSI suggested that the effect of increasing metabolism was either overestimated by HSI or underestimated by recommended WBGT action levels.