When wearing and removing the FFP3 mask, hold the straps on both sides of the FFP3 mask and do not directly contact the external surface of the mask. If you have ever shared a room with an infected person, or the mask becomes dirty, damaged, damp or stained with cosmetics, you'd better throw away the used mask at this time. It should also be noted that FFP3 mask cannot be sterilized in microwave oven or cleaned with water.