Climate & occupational health

Heat Stress

Meaning statusEstablishedSource recordDirect document linkedWhy these are different

Definition

Heat stress is the net heat load experienced by the body, combining metabolic heat generated by physical work, environmental heat and humidity, and the insulating effect of clothing or protective equipment. When the body's heat storage exceeds its ability to cool, heat strain results, ranging from heat exhaustion to potentially fatal heat stroke. WHO and WMO identify occupational heat stress as a growing global challenge as climate change intensifies heat extremes.

References

CDC/NIOSHHeat Stress and Workers — occupational heat stress as combination of metabolic heat, environmental heat and clothing; heat-related illnesses and risk factors

definition and prevention

WMOWHO-WMO report and guidance on workplace heat stress — billions of workers affected; productivity losses per degree; call for occupational heat action plans

global significance

Overview

What it means

Heat stress sits at the intersection of climate change, health, and labour rights: billions of workers — in agriculture, construction, and fisheries above all — face rising exposure, and productivity falls measurably with every degree above comfortable working temperatures. Prevention combines engineering controls, work-rest cycles, hydration, acclimatisation, and heat action plans.

How it is used

The concept structures occupational exposure limits (often via WBGT indices), national heat rules for outdoor work, climate-adaptation planning, and ILO/WHO worker-protection guidance.

Why it matters

It is one of the most direct ways climate change is already harming working people — a core social-sustainability risk.