Heat Stress Hazards
Heat Index and Wet Bulb Globe Temperature (WBGT)
The heat index is a measure that combines air temperature and humidity to show how hot it feels. For example, if the temperature is 90°F but the humidity is high, it might feel like it’s 100°F. The higher the heat index, the more dangerous it is to work under these conditions. Tap here to add the OSHA-NIOSH Heat Safety Tool App to your smart phone. Also, most smart phone weather apps can provide the "feels like" temperature, which is the adjusted heat index.
The Wet Bulb Globe Temperature (WBGT) is another way to measure heat stress. It considers:
- Air Temperature: The actual temperature of the air.
- Humidity: The amount of moisture in the air.
- Radiant Heat: Heat from the sun or hot surfaces.
- Air Movement: Wind or fans that help cool the body.
The WBGT gives a more complete picture of heat stress because it includes more factors that affect the perceived temperature. It’s often used in workplaces to determine when it’s safe to work outside or in hot conditions. Meters can be used to measure both the heat index and the WBGT, which are critical tools for assessing heat stress in various environments.
WBGT Demonstration
Understanding these measures helps employers and workers make informed decisions about when to implement safety measures, such as taking breaks, hydrating, or adjusting work schedules to prevent heat-related illnesses.
Knowledge Check Choose the best answer for the question.
2-2. How does the Wet Bulb Globe Temperature (WBGT) provide a more complete picture of heat stress compared to the heat index?
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