---
title: "What Is Heat Stress? Heat Stress and Hydration Glossary"
description: "Heat stress is the total heat load on a worker's body from hard work, hot air and sun, and clothing or gear."
url: https://jmarsolutions.multisites.ai/glossary/heat-stress
publisher: JMAR Solutions
phone: +1-214-632-7780
quote: https://jmarsolutions.multisites.ai/contact
---

Heat illness

# Heat stress

Heat stress is the total heat load on a worker's body from hard work, hot air and sun, and clothing or gear. When the body cannot shed that heat, illness can follow.

Heat stress is the heat your body takes on, not just the weather. Three things add up: the heat your muscles make when you work, the heat in the air and sun, and the heat that clothing and gear trap. Hot, humid, still air makes it worse.

More heat stress raises the risk of a [heat-related illness](https://jmarsolutions.multisites.ai/heat-illness). Workers who are new to the heat face more risk, so [acclimatization](https://jmarsolutions.multisites.ai/glossary/acclimatization) matters. Tools like the [heat index](https://jmarsolutions.multisites.ai/glossary/heat-index) and [WBGT](https://jmarsolutions.multisites.ai/glossary/wbgt) help crews judge the load. Read the full plan in our [heat stress prevention guide](https://jmarsolutions.multisites.ai/heat-stress-prevention).

[From JMAR SolutionsHydration programs and toolbox talks for crews](https://jmarsolutions.multisites.ai/hydration-programs)

## Related terms

-   [Heat exhaustion](https://jmarsolutions.multisites.ai/glossary/heat-exhaustion)
-   [Heat index](https://jmarsolutions.multisites.ai/glossary/heat-index)
-   [WBGT](https://jmarsolutions.multisites.ai/glossary/wbgt)
-   [Acclimatization](https://jmarsolutions.multisites.ai/glossary/acclimatization)
-   [Water rest shade](https://jmarsolutions.multisites.ai/glossary/water-rest-shade)

## Sources

1.  [CDC NIOSH: Heat Stress and Workers](https://www.cdc.gov/niosh/heat-stress/about/index.html)

![Ironworkers silhouetted on a steel frame against a hot orange sunset](https://jmarsolutions.multisites.ai/_astro/sunset-steel.IhAMDca0_6wk53.webp)

## See it on your crew in 15 minutes

Jennifer walks your safety team through the drops, the protocol and the numbers on a short live call.

[Book a 15-minute demo](https://calendly.com/jen-jmarsolutions/15-min-meeting)