Always read and follow the manufacturer’s directions when using an N95 mask. It must cover both the nose and mouth to keep you from breathing in mold and dust. If it does not have a snug fit, it will not work properly. Correct fit of the mask requires contact with smooth skin. It will not work properly for people with beards or facial hair. Even one-day beard growth has been shown to let air leak in. Always use both straps on the mask to hold it in place to keep air from leaking around it.

Do a user seal check, including both positive and negative pressure checks, to verify that you have correctly put on the mask and adjusted it to fit properly.

• Negative pressure check

  Place both hands completely over the mask and inhale sharply. Be careful not to disturb the position of the mask. The mask should pull into your face. If air leaks around your face or eyes, adjust the nosepiece and straps and repeat the positive pressure check.

• Positive pressure check

  Put your hands over the mask and breathe out sharply. If your mask has an exhalation valve (like the one pictured above) be sure to cover the exhalation valve when you exhale. No air should leak out of the mask if it fits properly. If air leaks out, re-adjust the nosepiece and straps and repeat the negative pressure check.

As the N95 mask gets clogged, it becomes more difficult to breathe. When this occurs, throw it out and use a new one. Discard the mask if it is wet or dirty on the inside, if it is deformed, or if the filter is torn. A deformed mask may not fit properly. An N95 mask cannot be cleaned or disinfected.