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What is liquid nitrogen and when is it deadly?

A leak at a Georgia poultry plant killed six people Thursday.
A tank of liquid nitrogen at the Prime Pak Foods poultry processing plant, in Gainesville, Ga., on Thursday.Elijah Nouvelage / AFP - Getty Images

A liquid nitrogen leak at a Georgia poultry plant killed six people Thursday and left several others hospitalized, including a firefighter who responded, local officials said.

At least three of those injured at the Foundation Foods Group plant in Gainesville were reported in critical condition.

Poultry plants often rely on refrigeration systems that can include liquid nitrogen, which vaporizes into an odorless gas capable of displacing oxygen when leaked into the air.

Nitrogen is a naturally occurring element needed for both growth and reproduction in plants and animals. It is also found in the air we breathe. When it is substantially cooled, it can become liquid.

Liquid nitrogen is so cold that it freezes anything it touches, according to the University of Wisconsin-Madison. It clocks in around 320 degrees below freezing. Because it's so cold, liquid nitrogen immediately boils when it touches anything room temperature, which is what causes the cloudy smoke seen in fancy cocktails and frozen desserts.

When liquid nitrogen is exposed to the air, it can turn into a gas. Oxygen levels can drop when this happens and can lead to headaches, lightheadedness and even the loss of consciousness.

According to the Food and Drug Administration, liquid nitrogen is non-toxic but can cause severe damage to skin and internal organs if mishandled or ingested because of the extremely low temperatures it maintains.

Inhaling the vapor released by a food or drink prepared with liquid nitrogen may also cause breathing difficulty, especially among individuals with asthma, according to the FDA.

Injuries have been reported after handling or eating products prepared by adding liquid nitrogen immediately before consuming, even after the liquid nitrogen has fully evaporated.

In enclosed areas, liquid nitrogen leaks can become deadly by pushing away breathable air, the U.S. Chemical Safety Board has warned. Between 2012 and 2020, 14 people died from asphyxiation linked to nitrogen in 12 separate workplace accidents, according to the U.S. Occupational Safety and Health Administration.

The potential for injury or death prompted the Washington State Department of Labor & Industries in December to issue a hazard alert for workers who might encounter liquid nitrogen. According to the notice, several workplace accidents involving liquid nitrogen have occurred in the state, including dangerously low levels of oxygen in an ice cream parlor where liquid nitrogen was used to flash-freeze ice cream.