How hot is the human body?

Heatwaves are being intensified by climate change – they last longer, become more frequent and hotter.

One of the questions many people ask is, “When will it be too hot for normal daily activities as we know it, even for healthy young people?”

The answer goes beyond the temperature you see on the thermometer. Also about humidity. And research by Larry Kenny, professor of physiology, kinesiology, and human performance, Daniel Vecellio, geographer and climatologist, and postdoctoral fellow, and Rachel Cottle, Ph.D. become dangerous faster than scientists thought.

Scientists and other observers have been concerned about the increased frequency of heat waves associated with high humidity, which is measured as “wet-bulb temperature”.

People often cite a study published in 2010 that suggested that a wet bulb temperature of 35 degrees Celsius — equal to 95 degrees Fahrenheit at 100% humidity, or 115 degrees Fahrenheit at 50% humidity — would be the upper limit of safety, as they The body can no longer cool itself by evaporating sweat from the surface of the body to maintain a constant body temperature.

This limit has only recently been tested in humans in a laboratory setting. The results of these tests show even more cause for concern.

To answer the question “How hot is it?” the researchers brought young, healthy men and women to Knoll’s lab at Pennsylvania State University to experiment with heat stress in a controlled environment.

These experiments provide insight into combinations of temperature and humidity that are starting to become harmful even to healthy people.

Each participant swallowed a small telemetry tablet that monitored their body temperature or body temperature. They then sat in an eco-room, moving around enough to mimic the minimal activities of daily life, such as cooking and eating. The researchers slowly raised either room temperature or humidity and monitored when core body temperature began to rise.

This combination of temperature and humidity at which a person’s core temperature begins to rise is called the “environmental critical limit”.

Below these limits, the body is able to maintain a relatively constant internal temperature over time. If these limits are exceeded, the internal temperature constantly rises, and with prolonged exposure, the risk of heat-related diseases increases.

When body temperature rises, the heart has to work harder to pump blood to the skin and dissipate heat, and when you sweat, it also reduces the amount of fluid in the body. In the most severe cases, prolonged exposure can lead to heatstroke, a life-threatening problem that requires immediate cooling and treatment.

Dry and wet environment

The current heatwaves around the world are approaching these limits, if not exceeding them.

In a hot and dry environment, the critical environmental limits are not determined by the temperature of the wet follicles because nearly all of the body’s sweat evaporates, cooling the body. However, the amount of sweat a person can produce is limited, and we also get more heat from higher air temperatures.

Keep in mind that these breaks are solely dependent on your body temperature not getting too high. Even low temperatures and humidity can cause stress to the heart and other body systems.

While exceeding these limits is not necessarily the worst case scenario, prolonged exposure can become extremely dangerous for vulnerable populations such as the elderly and people with chronic diseases.

Our experimental focus has now shifted to testing older men and women because healthy aging makes people less resistant to heat. In addition to increasing the prevalence of heart, respiratory and other health problems, as well as certain medications, this can increase the risk of their harm. People over the age of 65 make up about 80-90% of heatwave victims.

How do you keep yourself safe

Maintaining water balance and finding places to cool off, even for a short time, are very important in high temperatures.

As more cities in the United States expand cooling centers to help people escape the heat, there will still be many people who will experience these dangerous conditions without any way to cool off.

A recent study on heat stress in Africa found that the climate of the future will not be conducive to the use of low-cost cooling systems such as “bog coolers” as tropical and coastal regions of Africa become wetter.

These devices, which use much less power than air conditioners, use a fan to recirculate air through a cool, damp pad to reduce air temperature, but become ineffective at wet follicle temperatures above 21°C (70°F).

Finally, evidence continues to grow that climate change is not just a problem for the future. This is the problem that humanity is currently facing, and it must be tackled head-on.

Source: Science Alert.