CHICAGO (CBS)—The best advice for avoiding the adverse affects of the extreme cold gripping the Chicago area this week is to stay indoors, but if you must venture out in the sub-zero temperatures, experts say to avoid frostbite and hypothermia by dressing in layers and covering exposed skin.

Frostbite

Frostbite can take effect in only a matter of minutes, according to Dr. Edidiong Kaminska, a dermatologist at Northwestern Medicine. Extremities such as fingers, toes, the nose and ears are at the highest risk for frostbite, but any area of exposed skin can be affected.

Skin freezes when the body’s survival mechanisms kick in to protect the body’s vital organs.

“Frozen skin can cause an inflammatory cascade in the body,” Dr. Kaminska said. “The tissue freezes, and while it’s thawing out, inflammation starts to spread.”

Starting Tuesday night, temperatures are expected to plunge to 20 below zero, with wind chills that could dip as low as 55 below. The extreme cold is expected to stretch through Thursday, and city officials are taking the cold spell seriously.

“I don’t know if we’ve ever seen temperatures like this, so the recommendation is to avoid being out there at all,” Dr. Kaminska said.

The National Weather Service says frostbite takes effect in four stages.

During first-degree frostbite, ice crystals start forming on the skin. In the second phase, skin starts to feel warm. The third stage is usually marked by the skin turning red, pale or white. In stage four, pain lasts for more than a few hours and skin could start turning black or blue.

“If the skin turns white and blisters start to form, it means ice crystals have formed in the skin tissue,” Dr. Kaminska said.

If you come inside from the cold and suspect you might have frostbite, sit by a warm fireplace, get under a warm blanket or engage in a mild form of exercise to get the body moving. If your condition doesn’t improve, you should see a doctor.

Hypothermia

When the cold causes your metabolic rate to slow down and the body temperature reaches 96°F or lower, hypothermia kicks in.

Kids and the elderly are more susceptible to hypothermia than young adults, Dr. Kaminska said.

National Weather Service data shows that of the approximately 1,300 people the CDC lists as being killed by hypothermia each year, most are seniors.

“As you age, your body becomes less efficient at letting you know when you are too cold,” according to weather.gov. “In addition, older people tend not to shiver effectively, one of the ways the body warms itself up.”

Aside from age, some medicines, problems with circulation, and certain illnesses may reduce your ability to resist hypothermia.

Unlike frostbite, Dr. Kaminska said, hypothermia has the potential to affect major organs like the brain.

“If someone starts stumbling on their words, that can be a sign that it’s started to affect the brain,” she said. “That’s a medical emergency and that person should see a doctor right away.”

Dr. Kaminska offers these tips on staying safe in the cold if you have to be outdoors: 

-Dress in 2-3 layers, including multiple socks, pants and shirts

-Wear cotton or wool and avoid synthetic materials

-Stay hydrated

-Avoid alcohol because being intoxicated can numb the senses and make you less aware of cold it is

-Avoid going outside in the cold with wet skin and hair.

-Cool down before going outside after a workout. “In a warm environment, your face reddens, and when you go outside in the cold sweat freezes quickly and blood vessels quickly narrow,” Dr. Kaminski said. “It can increase the risk of frostbite and hypothermia if you’re outside for a long time.”

Chicago Mayor Rahm Emanuel gathered with city officials Monday to talk about safety in the cold weather.

Their advice was to stay inside and to help the elderly and homeless by calling 311 if someone doesn’t have shelter or enough heat in their home.

“We continue to urge residents to help each other out and take all necessary precautions,” said Rich Guidice, executive director of the Office of Emergency Management and Communications. “Snow and extreme cold are not only inconvenient but also very dangerous. To that end we ask everyone to limit their time outdoors and work remotely from home when possible.”

City officials said property owners are required to ensure thermostats are warmed to at least 66°F.

“If you’re a renter and your landlord isn’t providing adequate heat, call 311 if the landlord doesn’t respond,” said Judy Frydland, the commissioner of the Department of Buildings for the City of Chicago. “We take heat complaints very seriously. We will carefully be monitoring calls this week and for the remainder of the winter season.”

Landlords face fines of up to $500 per day per violation while a tenant is without heat, Frydland said.

Four building owners out of 88 inspected over the weekend were ticketed, she said.

At Chicago Public Schools, school officials are expected to decide by noon on Tuesday whether to cancel classes on Wednesday, which is expected to be the week’s coldest day.