The number of cold-exposure cases in New York City tripled in the weeks after Hurricane Sandy struck compared with the same period in previous years, the health department reported in an alert to thousands of doctors and other health care providers on Wednesday.
And even though power and heat have been restored to most of the city, there are still thousands of people living in the cold, the department said.
The department warned health care providers that residents living in unheated homes faced “a significant risk of serious illness and death from multiple causes.”
The number of cases of carbon monoxide exposure, which can be fatal, was more than 10 times as high as expected the week of the storm and 6 times as high the next week, reflected in greater numbers of emergency department visits. Calls to the city’s poison center also increased, health officials said.
And as temperatures dip, health officials said the cold could lead to other health problems, including a worsening of heart and lung diseases and an increase in anxiety and depression.
“My bigger concern is what happens in the future as we get closer to winter in the next four weeks,” Dr. Thomas A. Farley, the city’s health commissioner, said in an interview. “There are probably about 12,000 people living in unheated apartments right now.”
Between Nov. 3 and 21, more than three times as many people visited emergency rooms for cold exposure as appeared during the same time periods from 2008 to 2011, the health department said. The storm hit on Oct. 29.
It took days before many elderly and disabled residents, trapped in cold, dark apartments without working elevators or phones, were visited by emergency responders and health workers. Some went to emergency rooms.
Dr. Farley said prolonged exposure to cold even slightly below room temperature could be deadly, and he urged residents of unheated apartments to consider relocating. He said they could find help by calling 311.
The alert said residents in cold apartments should wear layers of dry, loosefitting clothing. They should not use ovens or portable gas heaters because of the risks of fire and carbon monoxide.
The statistics were collected through a system that gathers major complaints daily from most of the city’s hospital emergency departments. The number of hypothermia cases reported to the system since the storm is 65, but that is considered an undercount.
Health department officials said the figure also did not reflect the much larger number of people whose underlying heart and lung problems had worsened in cold environments. An increase in asthma attacks, heart attacks and stroke would be more difficult to detect immediately. Officials said both the very young and older people, as well as people with chronic diseases, mental illness and substance use, were most at risk.
Dr. Farley said the increase in hypothermia cases was greatest immediately after the hurricane and during the cold period around the northeaster on Nov. 7.
Some people exposed to cold were treated at Staten Island University Hospital. “Our initial cases were people immersed in water, most in the process of being rescued,” said Dr. Brahim Ardolic, chairman of the hospital’s department of emergency medicine.
Makeshift efforts to keep warm also caused health problems. Many city residents without heat used stoves and, in some cases, generators indoors or in garages, leading to exposure to carbon monoxide, a colorless, odorless gas.
“It’s a really scary exposure because you usually don’t realize what happened,” Dr. Ardolic said. “It can be insidious enough that you can go to sleep and wake up, if you’re lucky, with a severe headache. If you’re unlucky, you just won’t wake up.”
One post-storm patient was Hazel Mintz, 90, who lives on the 12th floor of an apartment building in Far Rockaway, Queens, that lost heat. She was taken to the emergency room after the storm because of chest pain. Days later, after neighbors heard a carbon monoxide alarm and smelled something burning in Ms. Mintz’s empty apartment, a caregiver opened the door to find a blackened kettle atop a burner with a gas flame. “I put on the gas to warm up,” Ms. Mintz, who has recovered, said.
At St. John’s Episcopal Hospital in Far Rockaway, one of the areas hardest hit by the storm, 13 people have been treated for carbon monoxide exposure since the storm, including a family of three burning charcoal indoors to keep warm, said Dr. Rajiv Prasad, the emergency department director.