Harvard Study Reassesses Human Survival Threshold
A recent study by Harvard researchers challenges the long-standing belief that the human survivability limit for wet-bulb temperature is 35°C, proposing a lower threshold of around 31°C for safe human endurance.
What is Wet-Bulb Temperature?
- Wet-bulb temperature refers to the lowest temperature that air can reach through evaporation of water at constant pressure.
- It is measured by wrapping a wet cloth around the bulb of a thermometer and allowing the water to evaporate.
- The cooling effect from evaporation lowers the thermometer reading, providing the wet-bulb temperature value.
- This metric reflects both heat and humidity, making it more realistic for assessing human heat stress than air temperature alone.
- A high wet-bulb temperature means evaporation (and thus sweating) becomes less effective, reducing the body’s ability to cool itself.
- It is a critical factor in areas like climate science, agriculture, health, and disaster preparedness.
- Conditions above the survivability threshold—even for short periods—can lead to fatal heat stress, particularly in vulnerable populations.
