US EPA

2072404 

Journal Article 

A Correlation of the Wet-Bulb Globe Temperature and Botsball Heat Stress Indexes for Industry 

Dernedde, E 

1992 

Yes 

American Industrial Hygiene Association Journal
ISSN: 0002-8894 

NIOSH/00207494 

53 

3 

169-174 

The correlation between the wet bulb globe temperature (WBGT) and Botsball temperature (BBT) was examined. WBGTs and BBTs were calculated for 154 combinations of ambient air temperature in the range 20 to 60 degrees-C, radiant heat fluxes of 450 to 1500 watts per square meter, air speeds of 0.3 to 1.5 meters per second, and ambient water vapor pressures of 5 to 45mmHg using established heat and mass transfer relations. The calculated WBGTs and BBTs were compared with values obtained in industrial and environmental surveys and laboratory experiments. Attempts were made to correlate the WBGTs and BBTs using regression techniques. A plot of the calculated WBGTs versus calculated BBTs had a large scatter indicating that the WBGT and BBT could not be connected by a simple linear relationship. Regression curves of the experimentally determined WBGTs and BBTs coincided with the scattergrams. Multiple regression analysis indicated that a single unique correlation between WBGT and BBT did not exist. The best correlation was obtained with an equation that expressed WBGT as a function of BBT and the water vapor pressure of the ambient air (equation-A). A mathematical simulation of heat stress in a casting operation in an aluminum production facility indicated that equation-A could predict the WBGT from the BBT with a precision of +/-1.18 degrees. The author concludes that a unique relationship between the WBGT and BBT does not exist. The WBGT can be predicted from a BBT measurement with a precision of +/-1.18 degrees if the water vapor pressure of the ambient air is known.