Can you get frostbite from air duster (canned air)?

Yes, if liquid refrigerant is expelled on comes in contact with your skin. Most duster contain refrigerant that is liquid when held under pressure. The goal of duster is to spray the vapor not the liquid, so the valving is designed to capture the vapor from the top of the can. When you shake a can, turn it, or flip it upside-down, you can introduce the liquid refrigerant to the mix.