It's so cold in parts of America that people are being urged to "avoid taking deep breaths" and to "minimise talking."

The US's midwest is currently experiencing some of the lowest temperatures ever recorded as a polar vortex spins across the country. The weather event, which usually travels around the North Pole, has led to temperatures as low as -50F in some states and an expectation of up to eight inches of snow and winds as fast as 40m/ph. Chicago has been particularly affected by the bad weather with chill wind warnings in effect and freezing temperatures that could "lead to frostbite in just minutes." ABC News reports that public transport cancellations have been caused by the extreme weather. Doctors have also warned that just five minutes of exposure to the icy winds could cause tissue damage in a healthy person. The US National Weather Service (NWS) has warned people to "avoid taking deep breaths" in the cold and to "minimise talking." Failing to do so could lower a person's core body temperature and make them more vulnerable to hypothermia. "Know the signs of frostbite and hypothermia. Keep your clothes dry. Bring animals and pets indoors, if possible," they said.

“Check on the elderly. In summary, please be smart and take care of one another. “Extremely cold air comes every winter in at least part of the country and affect millions of people across the United States. The Arctic air, together with brisk winds, can lead to dangerously cold wind chill values."

The service also urged people to stay indoors and be wary of frostbite, which could affect the body "within minutes." “Areas most prone to frostbite are uncovered skin and the extremities, such as hands and feet," they said.