The number of deaths blamed on a week of intensely cold temperatures rose to 13 on Wednesday, reminding many Americans about the dangers of hypothermia and exposure.
But the cold weather may have a much larger hidden death toll.
Dr. Jeffrey Guy says many of the cold-related injuries and deaths during this cold snap have been the direct result of fires accidentally or intentionally set by people.
"The numbers are significant," said Guy, an associate professor of surgery and director of the burn center at Vanderbilt University Medical Center in Nashville, Tenn.
"Everyone is looking at exposure-related injuries, such as hypothermia, but these people are setting their houses on fire while trying to stay warm."
Guy says the extended duration of cold weather has resulted in an increased number of patients in his 29-bed burn unit.
Some of the patients leave the medical center after treatment for their injuries. Some do not.
"If you count the deaths across the South, there have probably been 20 fire-related deaths in the past two weeks," Guy said. "And these are just the deaths."
The severity of the cases range from relatively mild injuries on the arms and legs to burns over 60 percent of the body. "We really get patients across the spectrum," Guy said. "There's not one specific injury."
What most of Guy's patients have in common is that they are poor. Many of them live in older homes, sometimes dating back to the Civil War. Many of these Southern-style homes have no heat, while others have faulty, aging heaters.
In order to create warmth, people living in these homes often use space heaters. These heaters, Guy says, are a major cause of the burn cases that he treats.
"In the past two weeks, we've had maybe four or five kids who have set their clothes on fire by sitting too close to a space heater," he said.
Overloaded electrical circuits and fireplaces that have not been properly maintained can also spark deadly fires.
Two such infernos on Tuesday razed family homes in Tennessee and Kentucky. In one of these fires, four children ranging in age from 7 to 14 were killed. In another, six children and four adults perished.
"Two entire families got wiped out," Guy said. "It is a horrible tragedy."
Another potentially deadly indoor cold weather threat is carbon monoxide.
According to figures from the Centers for Disease Control and Prevention, this colorless and odorless gas is the leading cause of poison-induced deaths in the United States, responsible for around 3,500 to 4,000 deaths each year.
Prolonged exposure can also lead to brain damage.
Particularly dangerous is the confusion and lethargy that accompanies carbon monoxide poisoning, which often makes it impossible for victims to seek help.
And cases of carbon monoxide poisoning spike during periods of cold weather.
"This is a problem that often has to do with a faulty furnace," Guy says. "People sometimes will try to run their stoves and do some other things indoors that open them up to carbon monoxide exposure."
In addition to indoor emergencies, there is always the concern of exposure to chilling temperatures.
During winter weather snaps, "Cold weather injuries always spike in incidence," said Ferdinando Mirarchi, an emergency medicine physician at Hamot Medical Center in Erie, Pa.
Certain groups are at greater risk of injury or death than others. Elderly people -- particularly the poor elderly -- make up one of these groups.
"We recently had an elderly man die from hypothermia because he felt he could not afford to keep his heat on," Mirarchi said. "He, like many other elderly, had medical conditions that would not allow him to readily compensate for the cold and generate body heat."
Asthma sufferers also have pre-existing medical conditions that put them at greater risk of injury from cold weather. And the recent cold snap has sent many of these patients to emergency rooms in affected areas.
"We have seen a several hundred percent increase in new and existing patients with asthma coming in for urgent and emergency care due to the extreme cold air," said Dr. Clifford Bassett, assistant clinical professor of medicine at the New York University School of Medicine.
"In particular, the cold 'dry' air is a very significant trigger for children and adults with asthma," Bassett said.
For families who are poor, the unusually cold weather presents a difficult dilemma: Stay warm, or stay safe?
Guy says that though this is a difficult decision for many to make, safety is paramount.
"It is probably better to be cold at 50 degrees than for your house to burn down," he said.
However, in dangerously chilly temperatures, there are certain things that people can do to keep themselves and their families safe.
Do not use space heaters in the proximity of anything flammable. Likewise, do not get too close, as the small but powerful heater can often cause clothes to catch fire.
If you live in an older home, make certain your furnace is properly maintained.
Do not overload electrical circuits, as a short circuit may result in an electrical fire.
If you are using a fireplace, make certain it is clean and that the flue is opened during use.
Invest in a smoke detector and, if necessary, a carbon monoxide detector.
Limit exposure to the cold, particularly if you are elderly or have a condition that makes you susceptible to low temperatures.