To understand the dangers of dry ice, one must understand what it is. Dry ice is frozen carbon dioxide. It is extremely cold (-109.3°F or -78.5°C). Remember that water freezes at 32°F or 0°C. Dry ice does not “melt” at normal atmosphere pressure, instead going from solid to gaseous states with no liquid between. Because of these physical properties, dry ice is both useful and dangerous.
Dry ice is used for a wide range of applications, including blast cleaning, refrigerant in situations where there is no electrical, party tricks and special effects, science experiments and more. In all cases, some common sense can help reduce the dangers of handling and using it. Understanding that dry ice is extremely cold and creates a heavy, cold, gas that sinks to the floor should make the advice to use gloves or tongs when handling it and to use it in a well ventilated area simply smart moves. Yet, there are still those who do things like place dry ice in a closed car with the AC on and become mystified as to why they cannot breathe. Here then is a clear list of the ways dry ice can be dangerous and why the danger exists.
Asphyxiation/Carbon Dioxide poisoning
Frozen solid, pure Carbon Dioxide exists in a state under light enough pressure that allows it to go directly to a gaseous state. This gas is still extremely cold and dense, sinking to the floor. For children, pets and those low to the ground, the danger of suffocation is ever present. In enclosed spaces, the denser CO2 can push out the lighter air making everyone at risk. The preventive is to ensure that the location has proper ventilation so that there is fresh air. If you start panting as though you have run a long distance, get away from the dry ice, preferably outside.
Frostbite/Dry ice burn
At -109.3°F or -78.5°C, dry ice is much colder than frozen water. While this makes it a great refrigerant, it also means it can kill skin on contact and cause “burns” from the extreme cold. These burns are just as painful and damaging as burns caused by extreme heat. Be smart and always wear gloves and use tongs or a scoop when manipulating dry ice. Also be aware that if you put dry ice in a drink to not swallow it or let it come into contact with your lips. The liquid will not prevent esophagus or stomach burns from it. The extreme cold will also crack counter tops and other surfaces so be aware of where you place it.
While preserving the cooling power of dry ice recommends it being stored in an insulated container, the fact that the carbon dioxide gas will continue to fill any empty space, even when normal atmosphere pressure is reached and beyond, using a sealed insulated container is a very bad idea. The pressure buildup can become great enough to explosively burst the container sending both dry ice fragments and parts of the container flying out like shrapnel. Not only can the ice pose a burn danger to those nearby but the loud noise can cause damage.
Common sense can make using dry ice fun and much safer. Solid carbon dioxide ice creates a dense heavy gas that is very cold. These are the two major factors to keep in mind when planning to use this material for refrigeration party effects, or blast cleaning. Proper handling equipment, area ventilation and storage practices are key to enjoying the mysterious and useful effects of dry ice safely.