In controlled trials, 12 healthy adults were exposed to extreme heat conditions of 42°C with 57% humidity, demonstrating the limits of human thermoregulation.

Participants struggled to complete a 9-hour exposure to these extreme conditions, showing a significant rise in core body temperature and indicating that dangerously high levels could be reached within 10 hours.

Dr. Kenny noted that the findings provide crucial data supporting the idea that humans can effectively regulate their body temperature under much harsher conditions than earlier models suggested.

Even in milder conditions, participants exhibited signs of uncompensated heat stress, emphasizing the body's difficulty in coping with prolonged heat exposure.

Understanding these physiological limits is crucial for guiding health policies and public safety measures in cities facing hotter summers.

With projections indicating that many densely populated areas may soon experience wet bulb temperatures above 32 °C, the study highlights the urgent need for adapting urban policies and healthcare systems to manage heat-related health risks.

The findings validate the use of thermal-step protocols in predicting human responses to extreme heat, which will aid in climate modeling and public health planning.

The research aims to integrate physiological data with climate models to better predict and address heat-related health issues as the world confronts climate change.

This study underscores the importance of understanding human physiological limits in the context of climate change, stressing that adaptation strategies must prioritize human health and survival.

A recent study from the University of Ottawa's Human and Environmental Physiology Research Unit has revealed that humans have a much lower tolerance for heat than previously thought, challenging the previously accepted survival limit of 35 °C wet bulb temperature.

New experiments indicate that the effective threshold for human thermoregulation is between 26 °C and 31 °C wet bulb temperature, significantly lower than earlier models suggested.

The research, led by Dr. Robert D. Meade and Professor Glen Kenny, focuses on the biological limits of thermoregulation, which is the body's ability to maintain its internal temperature under environmental stress.