Heat Stress Calculation Formula

Heat Stress Calculator




Introduction & Importance

Heat stress is a serious occupational health issue that can lead to heat exhaustion, heatstroke, and even death. Understanding and calculating heat stress is crucial for ensuring the safety and well-being of workers in hot environments.

How to Use This Calculator

  1. Enter the temperature, humidity, and wet bulb globe temperature (WBGT) values.
  2. Click the “Calculate” button.
  3. View the results and heat stress level below the calculator.
  4. Interpret the chart to understand the heat stress index (HSI) and heat stress risk.

Formula & Methodology

The heat stress index (HSI) is calculated using the following formula:

HSI = 0.1 * (0.4 * T + 0.6 * WBGT) + 0.1 * (0.4 * T + 0.6 * WBGT) * (0.001 * RH * (0.6 * T + 0.4 * WBGT))

Where:

  • T = Temperature (°C)
  • WBGT = Wet Bulb Globe Temperature (°C)
  • RH = Relative Humidity (%)

Real-World Examples

Data & Statistics

Heat Stress Levels and Corresponding HSI Values
Heat Stress Level HSI Value
No heat stress ≤ 26
Moderate heat stress 27 – 30
Severe heat stress 31 – 38
Extreme heat stress ≥ 39
Heat Stress Risk Categories
HSI Value Risk Category
≤ 26 Low
27 – 30 Moderate
31 – 38 High
≥ 39 Very High

Expert Tips

  • Stay hydrated by drinking plenty of water.
  • Wear light, loose-fitting clothing and a hat.
  • Take frequent breaks in cool, shaded areas.
  • Gradually increase your workload and allow your body to adapt to the heat.

Interactive FAQ

What is the wet bulb globe temperature (WBGT)?

WBGT is a measure of heat stress on the human body, taking into account temperature, humidity, and solar radiation.

How can I reduce heat stress in my workplace?

Implement engineering controls, such as ventilation and cooling systems, and administrative controls, like scheduling work during cooler hours and providing adequate breaks.

Heat stress calculation formula Heat stress prevention tips

OSHA’s Heat Stress Guide

CDC’s Heat Stress Information

NSW Government’s Heat Stress Guide

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