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WONDER QUEST with April Holladay, A Weekly Column * June 14, 2002* Albuquerque

Dry ice burns like fire

Q: Why does one feel a burning sensation when holding dry ice in his hand? Gabe, NY, NY

A: Dry ice (frozen carbon dioxide) is cold: -109 degrees Fahrenheit (-78 degrees Celsius). That's 109 degrees colder than most freezers, 141 degrees colder than water's freezing point, and almost as cold as Earth's coldest temperature: -129º F (89.4º C) recorded in Antarctica.

[www.DryIceBlasting.com] Dry ice nuggets and pellets

When you hold dry ice in your bare hand, you freeze the tissues of your skin: progressively inward. A mere two-second exposure starts the process.

The skin contains different sensors for cold and heat, says Michel B. Ducharme, head of the human protection and performance group with Defence R&D Canada. The sensors discriminate between cold and heat only within certain bounds. Touching dry ice overwhelms the discriminatory sensors and triggers pain. Freezing is a paramount threat to the body. You feel the pain as a burning sensation.

Frostbite, like heat burns, can be a nasty injury. In fact, safety warnings liken the two injuries: "May cause severe frostbite or burns," says one about dry ice. Even mild frostbite causes cells to freeze, crystallize, rupture, and die. In cases of severe frostbite, this can involve subcutaneous tissues, muscle, tendon, and bone.

Always handle dry ice wearing protective cloth or leather gloves. An oven mitt or towel will do.

(Answered Jun. 14, 2002)

Further Surfing:

dryiceInfo.com: how dry ice is made

MSDS glossary: dry ice

Rock-It science: dry ice experiments

Dry Ice Blasting: dry-ice blasting