Before someone gets full-blow heat stroke, what are the body's early reactions to excessive heat?
Heat rash and muscle cramps are early signs of people being overwhelmed by heat. If those aren't dealt with, it can lead to more severe symptoms.
Cramping of muscles can be for a number of different issues, including electrolytes not getting to the muscles.
People should be aware that their skin turning red and dry are indicators that heat is impacting them.
Who is the most vulnerable to extended high temperatures?
We know the risk factors for dying from heat are urban dwellers who are elderly, isolated and don't have access to air conditioning. Obese people are at increased risk as are people on certain medications. And people who are exercising or working in the heat, who don't meet those criteria, can be at risk.
What medications can make the body more susceptible to extreme heat?
In the study from the 1995 Chicago heat wave, we found that diuretics for high blood pressure were some that did, and beta blockers—a number of studies showed that people taking them could be at increased risk.
There are some studies that have shown that certain mental health medications may impact a person's ability to deal with the heat. But that's a difficult one to get at. When you look at the number of people who die in a heat wave and the number of people who are taking those medications, the numbers can get pretty small pretty quickly.
What's the hottest temperature a healthy human can tolerate?
We don't know that—no one knows that. There are different humans, different humidities, different types of temperature.
Have we not evolved to cope with super hot weather?
Certainly society has evolved in dealing with the heat—and that has been in the development of air conditioners. The number-one factor that ameliorates death from heat is access to air conditioning.
And I've read that fans don't work to prevent overheating in really hot temperatures…
Not only does it not work, it actually makes it worse. We compare it to a convection oven. By blowing hot air on a person, it heats them up rather than cools them down.
Are modern humans neglecting to do something our ancestors did to survive the heat?
I think it's always been a problem. There's history over hundreds of years of people dying of heat. Philadelphia in 1776 had a major heat wave that caused deaths.
We're also living to older ages, and we're more urban now than we have been in the history of the human species. That intense crowding can combine with the heat island effect in big cities. Our elderly people are also more isolated than they have been in the past, so those factors can play a part, too.
The IPCC, the Intergovernmental Panel on Climate Change, the thing that they are most comfortable in predicting, that the science is most solid for, is the increase in many parts of the world in the duration and intensity of heat waves.