Caution:
1.The mask isn't suitable for hypoxic environment which the oxygen concentration is below 19.5%.
2. The mask isn't suitable for the environment which the concentration of the pollutants is too high and damage health and life.
3.The mask isn't suitable for protecting against harmful gases or vapors.
4.The mask should be replaced with a new one when it is contaminated, damaged, or respiratory resistance has increased.