Dry ice is the solid form of carbon dioxide (CO₂), a molecule composed of one carbon atom bonded to two oxygen atoms. Unlike regular ice, which is frozen water, dry ice does not melt into a liquid. Instead, it transitions directly from a solid to a gas, a process known as sublimation. Direct contact with this substance can be dangerous due to its extremely low temperature.
Initial Contact
Touching dry ice immediately causes intense cold, which rapidly progresses to a burning or stinging feeling. The extreme cold quickly removes heat and freezes moisture on the skin. Prolonged contact can lead to serious injury, causing skin to become red and sensitive, similar to a heat burn.
Understanding the Extreme Cold
Dry ice maintains an exceptionally low temperature of approximately -109.3°F (-78.5°C). This is significantly colder than regular ice, which freezes at 32°F (0°C). The primary reason for its extreme cold is sublimation. During this process, dry ice absorbs a large amount of heat from its environment, including human skin, as it transitions directly from solid to gas. This rapid absorption of thermal energy explains the quick and intense cooling experienced upon contact.
The Risk of Frostbite
The most significant danger from touching dry ice is frostbite, the freezing of body tissue. The extreme cold causes blood vessels to constrict, freezing skin cells and potentially cutting off blood supply to the affected area. This can range from superficial damage to deep tissue injury.
Symptoms of frostbite include numbness, tingling, and a change in skin color to white, gray, or blue. Skin may develop a hard, waxy texture. In more severe cases, blistering can occur. Continued exposure can lead to irreversible tissue damage, with potential for secondary infections and gangrene, which is a medical emergency.
Handling Dry Ice Safely and Emergency Steps
Always use insulated gloves, tongs, or other protective barriers when handling dry ice. Never handle it with bare hands.
Proper ventilation is important when using or storing dry ice. As dry ice sublimates, it releases carbon dioxide gas, which can accumulate in enclosed spaces and pose a hazard. If accidental contact and frostbite occur, immediate first aid involves rewarming the affected area. Flush the affected skin with plenty of cold water, avoiding hot water or dry heat. After initial rewarming, seek medical attention for any suspected frostbite.