The Dangers of Compressed Air
Compressed air is cold, pressurized, and easily accessible. It is also NOT something that should be used on a human body. Its not just compressed air, it's a chlorinated propellant. (per a chemist I know) One of my close friends, normally a very careful domme, had witnessed a scene where people were using compressed air. During a mummification scene she was doing, she got the bright idea of inserting the nozzle of the compressed air canister into the saran bondage and giving a couple of squirts. The result was burns on the sub's scrotum from the pressurized cold of the air which had no way to dissipate under the saran wrap. My friend had not read the label, and had not thought of the effects of pressurized air in a VERY confined space. Extreme cold burns just like extreme heat. Neither is a good thing to subject skin to. To give her credit, she was very new at the time, and she makes a point of sharing this story with people who might make the same mistake. It's important to acknowledge mistakes so that others won't do the same thing.
The label on this can says, in part: "Do not breathe fumes. Avoid contact with skin and eyes. Use only in well ventilated areas." Most of us have this stuff around the house. I use it on the computers and stereo equipment. My sister uses it to dust artificial flowers. Its a common item, but like a lot of common household items, it's use on the human body is dangerous.
In it's customary uses, it is safe and harmless. After all, it wasn't designed to be used on pets or people. Using it for purposes that it was not designed for should be done very, very carefully, with a lot of forethought, if at all. Some things just don't adapt well to play. Aside from burns, compressed air can force air bubbles into the bloodstream or skin, also a dangerous idea. Not only is it really cold, it expands like crazy, and air bubbles can cause aneurisms. Spraying it into a body orifice can cause all sorts of havoc from burst organs, blood flow blockages, necrosis from internally burned tissue, strokes and death. If you want to give someone a sudden chill, ice cubes work just as well and are usually safer.