Of late each summer, about 20 in 1,000 Americans suffers from a heat-related illness, and that number is on the rise as the population ages, says James Glazer, assistant director of sports medicine at Maine Medical Center in Portland.
Experts say warning signs include muscle cramps, headaches, fever, nausea, fatigue and decreased urine output. They could signal the onset of:
• Dehydration, which occurs when the body does not take in enough fluid."For the most part, it's easily managed," says Michael Lopez of the Washington State Department of Health. "It's caused by environmental exposure to heat, and it can happen just from sitting in a non-air conditioned room."
Bill Howard of Union Memorial Hospital in Baltimore says dehydration can be dangerous because it can lead to heat exhaustion and heat stroke.
• Heat exhaustion, which occurs when the body cannot sweat enough to bring down its temperature.
• Heat stroke, a potentially fatal condition that occurs if heat exhaustion is untreated and body temperature tops 104 degrees.
There have been some well-publicized cases of wilting celebrities. In July, a popular rock star Kelly Rowland collapsed from dehydration while performing at the ThisDay music festival in Nigeria. She was treated at a nearby Lagos hospital.
Actress Nicole Richie was treated for dehydration in March and Lindsey Lohan collapsed from heat stroke and dehydration on a movie set in December.
"The thing is, you don't have to be a celebrity or a high-profile person to experience these things," says Greg Jantz, director of the Center for Counseling & Health Resources in Edmonds, Washington. "It happens to us all."
The elderly and young children are more vulnerable to the heat, but anyone can suffer from heat exhaustion, even those who are physically fit, says James King, a family physician in Selmer, Tenn. and president-elect of the American Academy of Family Physicians.
King recommends drinking plenty of water — before, during and after outdoor activities. "You need to drink significantly more than what you think you need to most of the time."
But this safety tip is not meant to be taken to extremes, says Glazer. Some people, especially athletes, can drink too much water, leading to hyponatremia, a condition that can cause seizures.
"People should be encouraged to drink enough, but drinking as much as you can probably isn't healthy," Glazer says. "Moderation is the best approach."
If you are experiencing symptoms, move to a cool place and drink sports drinks or water, doctors recommend.
"A lot of the time, these things occur because of stupidity," Howard says. "If you're going to be out in the heat, take care of yourself. If you get hot, cool off. If you get thirsty, drink."
Global warming will permanently change the climate of the American Southwest, making it so much hotter and drier that Dust Bowl-scale droughts will become common, a climate report released in April last concluded.
The changes are already taking place and will not be stopped for decades even by dramatic reductions in greenhouse gas emissions, the researchers said.
The drought that has affected much of the Southwest since 1999 may already be the result of global warming as much as regional weather patterns, they felt.
Energy from the sun drives the earth's weather and climate. The earth absorbs energy from the sun, and also radiates energy back into space. However, much of this energy going back to space is absorbed by "greenhouse" gases in the atmosphere.
Thanks to the presence of those gases, the atmosphere radiates most of this energy back to the Earth's surface, our planet is warmer than it would be if the atmosphere did not contain these gases. Without this natural "greenhouse effect" temperatures would be about 60ºF lower than they are now, and life as we know it today would not be possible.
Some greenhouse gases such as carbon dioxide occur naturally and are emitted to the atmosphere through natural processes and human activities. Other greenhouse gases (e.g., fluorinated gases) are created and emitted solely through human activities. Fluorinated gases are synthetic and are emitted from a variety of industrial processes.
During the past century humans have substantially added to the amount of greenhouse gases in the atmosphere by burning fossil fuels such as coal, natural gas, oil and gasoline to power our cars, factories, utilities and appliances.
The added gases — primarily carbondioxide and methane - are enhancing the natural greenhouse effect, and likely contributing to an increase in global average temperature and related climate changes, scientists say.