Ability of Basic Physiological Monitoring to Identify Excessive Occupational Heat Strain.

Abstract

This study assessed the ability of basic physiological metrics to differentiate between acceptable and unacceptable heat strain. A database of final core temperature ( Tre ), heart rate (HR), and skin temperature ( Tsk ) for 880 heat stress trials over a wide range of heat stress and clothing was created. Three case definitions based on Tre , HR, or fatigue were used to classify the trials as cases (unacceptable heat strain) or noncases (acceptable heat strain). The area under the receiver operating characteristic curve (AUC) characterized the discrimination ability of 15 individual physiological metrics. Generally, AUCs ranged from 0.85, allowing acceptable sensitivity with poor specificity to 0.50 with no predictive power. Tre , HR, and fatigue were independent limits of heat strain. A program of personal monitoring needs to recognize independent reasons to classify an exposure as unacceptable.