CHST Worksite Audit Practice Test 2026 - Free CHST Practice Questions and Study Guide

In outdoor WBGT, the three environmental factors are combined with specific weights to reflect how much each contributes to heat stress. The standard formula is WBGT = 0.7 × Twb + 0.2 × Tg + 0.1 × Ta, where Twb is the natural wet-bulb temperature, Tg is the globe temperature, and Ta is the dry-bulb (air) temperature. The Globe Temperature is multiplied by 0.2 because radiant heat from the sun and surroundings affects heat stress, but its contribution is smaller than the evaporative cooling impact captured by the wet-bulb measure. The wet-bulb component has the largest weight (0.7) since humidity and evaporative cooling dominate physiological strain in many outdoor conditions, and air temperature contributes modestly with 0.1. Hence the Globe Temperature term uses a 0.2 coefficient.