As the temperature of an extinguisher horn rapidly drops and freezes over, there is a risk that your hands will get ice burns. Since CO2 works by displacing the oxygen around the fire, it should not be used outside or in windy environments. CO2 is a high pressured extinguisher. It might make a class A or class F fire worse by being used on them. In small, enclosed spaces, users should exercise caution when discharging large amounts of CO2.