(MCT) – The intense heat bearing down on the Chicago area has already buckled pavement, canceled summer school classes and contributed to at least two deaths.
But the most dangerous part of the triple-digit highs could be yet to come, according to medical experts.
"It all comes down to cumulative effect," said Dr. Brian Sayger, vice chairman of emergency services at Advocate Christ Medical Center, which has seen about seven cases of heat exhaustion in the last several days.
"For individuals who are not able to replenish by hydrating and resting, each day becomes more taxing. ... It's like driving a car without filling the gas tank — eventually you run out."
Although "heat wave" is not technically used by meteorologists, Chicago has endured six consecutive days over 90 degrees, and it must brave yet another Friday, when temperatures are expected to surge past 100 again.
All that continuous heat can be tough on the human body. As the mercury spikes, people sweat to cool off. But over prolonged hot spells, the body can severely dehydrate, losing the ability to sweat and causing internal temperatures to soar and organs to shut down.
Schooled by 1995's devastating heat wave, in which more than 700 people died, city officials already have taken steps to try to prevent another disaster. Heat alerts, warnings and tips have been issued. Social service agencies are performing well-being checks. And cooling centers have opened, according to officials with the Office of Emergency Management and Communications.
By midday Thursday, the Chicago Fire Department had placed 10 additional ambulances on the streets to respond to calls for service, said spokesman Larry Langford.
"The city departments are able to monitor conditions as they develop," Langford said. "So much was on paper back then in the mid-1990s. Now, with computers, it's much more readily available for analysis."
The humidity in this heat wave also is working in the city's favor. Though it might not feel like it, dew points are lower than in 1995, when the temperature hit 104 but the heat index rose to around 120 degrees, according to WGN meteorologist Tom Skilling.
"That was like Amazon-level dew points," Skilling said. "This is more like Gulf-level dew points, which is still horrendously uncomfortable but not as oppressive."
For many, however, the temperatures this week still feel tropical.
Cynthia Vaughn, 39, started her day in a park but decided to leave after an hour outside in the scorching heat.
"I noticed it was getting hotter and hotter really fast," said Vaughn, who later made her way to a Garfield Park cooling center.
By the afternoon, nearly two dozen people had assembled at the center — some used the space to sleep while others gathered around the flat-screen TV. Dana Atkins, who has been homeless for a month and said she wasn't feeling good, rested her head on her arms as she tried to fall asleep.
"It feels a lot better in here," said Atkins, 42.
Still, the intense heat already claimed lives.
Authorities said heat was a contributing factor in the deaths of Jon McCullough, 48, from Lincoln Square, and Eugene A. Burns, 55, of Maywood. The office was investigating the death of a 95-year-old Chicago woman as possibly heat-related, but the autopsy was inconclusive, pending more tests.
A man who identified himself only as Burns' son believes his father did not die of heat-related causes, saying his father had a history of heart trouble.
"Unfortunately he had other ailments. It wasn't the heat — my father had been sick for a while," the man said by telephone.
Loyola University Medical Center officials said that by midday Thursday, about seven people were treated at the emergency room with heat-related ailments within 24 hours, including sunburn, heat exhaustion and breathing problems.
A train derailment on the Glenview-Northbrook border that killed two people was being partly attributed to the heat — authorities believe the steel rails may have expanded, contributing to the crash. Authorities also believe heat-expanded concrete and high winds caused a west suburban building to collapse, injuring two children.
Doctors advised people to drink lots of water and stay in air conditioning either at home or at a cooling center. Headaches, confusion, blurred vision, cramps and lack of sweating can be telltale symptoms of an overheating body, said Dr. Mark Cichon, chairman of emergency medicine at Loyola.
"Perspiring is the body's natural way of trying to cool off," he said. "If you're not sweating, you're in the danger zone."
Friday's forecast calls for high temperatures near 103 degrees, which led to more canceled summer school classes.
But relief is on the horizon, according to the National Weather Service.
Although temperatures are expected to remain in the 90s on Saturday, by Sunday they should sink into the low 80s, according to meteorologist Charles Mott.
"Relatively speaking, you could call it a cold front," Mott said.