By John McDevitt

PHILADELPHIA (CBS) — The elderly are particularly vulnerable to extreme cold, and a geriatric expert is offering tips on keeping senior citizens safe.

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Many senior citizens produce less body heat, and hypothermia can develop even during sleep, according to Jennifer Tapner, a registered nurse who is also executive director of the Watermark at Logan Square, a continuous-care retirement community.

“It would be good prevention to make sure they use extra blankets and to make sure that the temperature in your home is set appropriately,” Tapner tells KYW Newsradio.  “Cool homes with temperatures from 60 to 65 degrees can trigger hypothermia in older people.”

Tapner recommends keeping the thermostat at a minimum of 70 degrees for the elderly.

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And if an elderly person has to go outdoors, make sure they are bundled up with hat, gloves, and a scarf covering the mouth so air coming into the lungs is warmer.

And if person’s body temperature falls below 97 degrees, she warns, get help right away.

“You should call 911 for emergency help immediately.”

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