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Northeast city officials ask for help to keep the homeless safe from dangerous cold this weekend

With temperatures expected to plunge well below zero degrees Fahrenheit this weekend, homeless populations in major Northeast cities are facing life-threatening conditions.

Temperatures could fall to the single digits and even below zero in New York City, Philadelphia and Boston. Combined with wind, AccuWeather RealFeel® Temperatures could drop to minus 20.

New York City and Boston have declared a Code Blue, meaning temperatures will fall below 32 and those without shelter are at an extreme risk.

Simple tips to prevent and treat frostbite

New York City Mayor Bill de Blasio urged residents to take care of themselves and other New Yorkers during the cold weekend. He also said officials will be "aggressive" in making sure everyone gets pulled into a shelter.

Those who see someone who appears homeless are encouraged to call the Homeless Outreach hotline at (215) 232-1984.

In January, New York Gov. Andrew Cuomo issued an executive order designed to bring homeless people into shelters, sometimes against their will, during a Code Blue.

Those who refuse to go inside and who appear to be at risk for cold-related injuries will be involuntarily taken to a shelter.

"...there will be intensive outreach, trying to make sure that all homeless folks get off the streets - anyone who might be in danger gets off the streets," he said on Thursday. "That effort will be done with force."

Philadelphia residents can call the same line to reach Project HOME at (215) 232-1984 if they see someone in need of shelter.

Boston Mayor Marty Walsh reiterated the same idea. Officials will be out to help those in need find shelter and deliver blankets, food and clothing this weekend. He asked Bostonians to call 911 if they see someone who needs shelter or is not properly dressed.

Extreme cold, like what is in store this weekend, affects the body in a life-threatening way.

"Below freezing, the blood vessels farthest from the heart begin to constrict, slowing blood flow. As temperature drops further, cells can actually begin to freeze or develop ice crystals, causing cellular damage and tissue death," Dr. Trevor Pour, assistant residency program director for the department of emergency medicine at Mount Sinai Hospital said.

While the body will recover from mild frostbite, severe frost bite can lead to long-term skin, nerve or blood vessel damage, he said.

Combine cold with wind and moisture, such as snow or rain, the risk increases. When winds hit the 20-mph mark and temperatures drop below zero, hypothermia can develop in just 30 minutes. That time frame gets even smaller when clothes are wet.

"Just a few hours in below-freezing weather can lead to hypothermia in vulnerable populations," he said, stressing that children, the elderly and those with certain chronic medical conditions are at the highest risk.

In all three cities, additional shelters will be open this weekend.