If the warm weather season is testing your patience and sapping your energy this year, you aren't alone — temperatures are already climbing past 100 degrees in many areas this summer, and new research suggests it could be literally too hot to function.
The human body struggles to manage the heat and must work harder to stay cool starting at temperatures of 104 degrees Fahrenheit, according to a small study from researchers from the University of Roehampton in England.
The research team, building on a previous study, measured various health metrics of 13 adult volunteers who underwent an hour of rest under different temperature and humidity conditions, ranging from 82 degrees Fahrenheit up to 122 degrees.
The team recorded core and skin temperatures of the volunteers, as well as their blood pressure, heart rate, and breathing rate.
They found that participants' metabolic rate spiked at temps of 104 degrees, especially when that temperature was combined with high humidity.
The findings suggest that the human body has to work significantly harder to keep cool between 104 to 122 degrees, according to the research presented July 4 to 7 at the 2023 annual conference of the Society for Experimental Biology in Edinburgh, Scotland.
That's bad news as above-average temperatures continue to be recorded worldwide, and are expected to worsen as the summer goes on.
Heat advisories have swept across the US and beyond
Temperatures have already hit well over the 104 degree mark this summer in the US. Last month, Texas experienced a deadly heat wave, with some cities recording temps of more than 110 degrees. And the Washington Post heat risk tracker notes that more than 54 million people have been exposed to dangerous levels of heat in recent days, warning of temperatures over 100 degrees in states like Arizona, Louisiana, and Florida
This year has already broken records for excessive heat advisories, and above-average highs are expected to continue through the rest of the summer, according to meteorological organizations like the National Weather Service.
Humidity and exercise can increase the risk of heat stress injury
Heat isn't the only factor to worry about when it comes to summer safety. A high humidity combined with high temperature creates a phenomenon known as "wet bulb" conditions, which can be deadly.
In most hot weather, we can cool our bodies down by sweating, venting away excess heat as moisture evaporates off the skin. But when the relative humidity exceeds 95%, and temps are 88 degrees or higher, there's too much existing moisture in the air for sweat to evaporate. As a result, heat stress can build up, which can worsen the risk of serious health issues like heat stroke.
Signs of heat stress begin with dehydration, which can cause fatigue and cramping, and escalate to heat exhaustion, involving aches, nausea, and fever.
Heat stroke can follow, and is a life-threatening medical emergency characterized by confusion, red, dry skin, trouble breathing, rapid heart rate, and eventual organ failure.
Physical activity can worsen the risk of heat injury, especially high-intensity exercise which cranks up your heart rate and body temperature even more.
To protect yourself in hot weather, stay out of the sun as much as possible, drink plenty of water (and enough electrolytes to prevent a dangerous imbalance) and keep an eye out for early symptoms so you can cool down when necessary.
