When using an N95 mask, always read and follow the manufacturer’s instructions. It must cover both the nose and mouth to keep mold and dust out of your lungs. If it does not fit snugly, it will not function properly. A mask’s proper fit requires contact with smooth skin. It will not operate properly on individuals who have beards or facial hair. Even a single day of beard growth has been shown to allow air to enter. Always secure the mask with both straps to prevent air from leaking around it.