WBGT index revisited after 60 years of use.

The Wet Bulb Globe Temperature (WBGT) seems to be still used world widely for the evaluation of heat stress conditions and it is recommended by ISO and American Conference of Governmental Industrial Hygienists as a screening method. Unfortunately, many occupational health practitioners and users appear to be unaware of its limitations. As the ISO 7243 Standard, based on WBGT, is presently under revision, it is an appropriate time to review the validity and applicability of this empirical approach to evaluate heat stress. This article underlines the main issues about the WBGT index from a rational perspective.