Preface

My wife and I recently took a short vacation to South Florida, visiting the Everglades and Key West. It was a great chance to get away for a few days and enjoy the beautiful scenery and sun. While passing through Key Largo, we stopped briefly at an ice cream shop, and to my surprise, I discovered 'Nitrogenated Ice Cream.' For those familiar with it, it will be no surprise that the shop had a 'selfie station' where customers could snap a picture of themselves directly in front of their liquid nitrogen storage tank. An image of the liquid nitrogen tank located inside the ice cream parlour is on the next page. You will note that it is labelled as a 'selfie station' where customers are invited to take photographs of themselves and others.

I was painfully aware of the recent investigation report released by the US Chemical Safety Board of six fatalities that had occurred at the Foundation Food Group (FFG) facility in Gainesville, Georgia, due to asphyxiation by liquid nitrogen. This incident occurred on 28 January 2021, when the liquid nitrogen level rose and overflowed in an immersion freezer, releasing the liquid into a confined space, the room where the freezer was located.

This book describes this incident in more detail as a case study. The six deaths were due to oxygen deprivation, the most significant hazard associated with releasing nitrogen into confined areas. Two of these deaths occurred due to the release of liquid nitrogen. The other four deaths occurred when other employees attempted to investigate the release or rescue of the first two employees. In my experience, this is very common in nitrogen incidents due to the human urge to help others in trouble. Rarely is only one person killed by nitrogen. Frequently, another person, and sometimes several others, also die while attempting to render aid to those who are already down. This is precisely what happened at the Foundation Food Group facility.

A similar incident occurred in April 2013 at a beer brewery in Mexico where seven workers, including three company employees, were killed in a confined space entry accident while cleaning a beer fermentation tank. It was believed this incident occurred due to inert gas, either carbon dioxide or nitrogen, and all three of the employees died while attempting to rescue the four downed contractor employees.

So, while at the ice cream shop, I attempted to understand more about using liquid nitrogen in 'nitrogenated ice cream.' One of the high school-age workers explained how they use liquid nitrogen to freeze the mixture of dairy ingredients to make the ice cream. Please note that liquid nitrogen is stored in a cylinder located inside the shop under pressure (250-350 PSI). When released, the very cold liquid, at temperatures of -320 °F (-196 °C), is released into the environment. The liquid nitrogen cylinder was inside the shop, directly adjacent to the serving counter. I asked about safety, and she explained that 'if the alarm goes off, they are supposed to go outside.' Note how she explained that 'they are supposed to go outside'; she did not say they immediately go outside. This is the issue: when liquid nitrogen is released into a confined space, for example, into the ice cream shop, the nitrogen quickly displaces the oxygen in the room and can result in people being killed due to oxygen deprivation. Due to nitrogen's completely colourless and odourless properties, the victims are unaware of what is happening to them. In this book, you will see just how quickly this can happen and, unfortunately, how frequently it happens and how deadly it is.

This is exactly what happened at the Foundation Food Group, and six people were killed by hypoxia due to oxygen deprivation. Several others were hospitalized due to the effects of nitrogen exposure. This incident is covered in more detail in the What Has Happened / What Can Happen section of this book.

I asked the shop attendant if they had ever had a nitrogen release, and she explained, 'Yes, just two weeks ago, a pipe broke on the tank, and the nitrogen was released.' She said that the nitrogen (supercold) removed the lettering previously on the front lower part of the dairy counter, and sure enough, you could see that the lettering was smudged and essentially gone. She explained that this incident happened overnight when no one was in the shop.

After I returned home, I attempted to contact the business owner of the ice cream shop several times to no avail. Each time I call, I get a recording on the phone, something to the effect that this device is not set up to receive messages. I haven't given up and would certainly like to discuss this with the business owner and hear a little more about how safety is managed at this location. I was in the Nashville area leading a safe operations training course recently and mentioned my experience at this ice cream shop. I was surprised to hear from several attendees that there are shops of this type in the Nashville area, and I have since learned that there are also shops of this type in New Orleans and other major cities across the United States. This 'nitrogenated ice cream' appears to be a national trend. I have since learned of other nitrogenated alcoholic drinks, taking advantage of the refrigeration qualities of liquid nitrogen and the aesthetic value of 'smoking drinks.'

The stainless-steel tank is the compressed liquid nitrogen storage tank. The lettering on the tank says, 'Selfie Station,' where kids and others can have their pictures taken in front of it.

The caption says:

'SELFIE STATION - SPARKY LOVES SELFIES... TAKE YOURS HERE AND TAG US TO BE FEATURED ON OUR ACCOUNT. SPARKY WILL RANDOMLY PICK POSTS THAT HE LOVES AND SEND YOU A GIFT!!'

Ice cream shop interior: Key Largo, Florida.

Note that the lettering is missing from directly below the counter.

The lettering was removed by a release of supercold liquid nitrogen a couple of weeks before when a section of pipe associated with the nitrogen storage tank failed overnight. When I saw this and coupled it with my knowledge of the Georgia poultry processing facility where six workers were killed by nitrogen, this became the driver for trying to share these lessons learned and hopefully prevent another tragic incident from occurring.

This became the incentive to write this book and help get the message out about the safety aspects of working with or around nitrogen and other asphyxiants in any form. All nitrogen (and other asphyxiants) has the potential for the same hazards, including compressed nitrogen, liquefied nitrogen and pipeline-supplied nitrogen. They are all deadly because if released into a confined space, the nitrogen displaces oxygen, which is a hazard. One breath of nearly pure nitrogen and your brain shuts down, and even if you fall into clean air, you may not start breathing unless you are resuscitated. This is the severe hazard of nitrogen. Liquid nitrogen is also more likely to freeze your skin, resulting in frostbite or possibly severe cold burns due to the extremely cold temperature. Ingestion of even very small amounts of liquid nitrogen can destroy a victim's internal organs. Other gases such as carbon dioxide (frequently used as a fire suppressant), argon (frequently used for welding) and helium, among others, have very similar characteristics and hazards.

In this book, I cover several cases of nitrogen asphyxiation and asphyxiation by other inert gases. If you work with or near equipment containing nitrogen or other inert gases, I encourage you to become familiar with these hazards. Nitrogen and other inert gases can be managed safely, but it only takes one slip or omission for people to be killed.

I later learned that a liquid nitrogen release occurred at a similar ice cream shop in Weston, Florida, where one worker collapsed unconscious, and two responders, a firefighter and a deputy sheriff, were also overcome. The news video of this incident shows the glass shop windows completely iced over. One person was admitted to the hospital for treatment, and the shop was closed for several days.

In addition to the personnel safety hazards created by using nitrogen as a refrigerant in enclosed spaces, ice cream made with liquid nitrogen has resulted in severe injuries due to ingesting small amounts of liquid nitrogen. I'll talk more about this in the last chapter. Still, serious injuries to the digestive tract have occurred due to supercold nitrogen and the rapid expansion of the liquid nitrogen to vapour inside the digestive tract. As a result, at least one US agency has advised against consuming ice cream made with liquid nitrogen.

While I enjoy occasional ice cream, I can't support this trend. I don't support having a liquid nitrogen storage tank indoors where people, including children, are present. Knowing what has happened to others, I am also wary of the possibility of ingesting even a small amount of liquid nitrogen from eating something as delicious as ice cream.

In this book, we will spend most of our time reviewing the background of using nitrogen in industry and elsewhere, the hazards of working with and around nitrogen, and case studies associated with incidents involving nitrogen and nitrogen asphyxiation. Due to the hazards of other asphyxiants and the similarities with nitrogen, we will also discuss several other inert gases and cover several case studies where they were involved. Near the end of the book, there is also a summary of US Occupational Safety and Health Administration (OSHA) NITROGEN ASPHYXIATION...