A report on U.S. National Public Radio notes that although N95 respirators and surgical facemasks are not guaranteed to prevent you from catching the flu, both can provide protection.
Sick people can limit the spread of germs by wearing face masks. Face masks are loose fitting, disposable masks that cover the nose and mouth. They are designed to prevent the wearer from spreading potentially contaminated airborne particles to people. Face masks are not designed to protect the wearer from breathing in airborne particles, like the flu.
Meanwhile, respirators can prevent the wearer from breathing in very small airborne particles which might carry viruses. Respirators fit tightly to the face so that most of the air is inhaled through the filter material.
However, to be effective, respirators must be worn properly.
Following that advice isn't as easy as it sounds. One study found that only 25 percent of volunteers enrolled in a mask-wearing experiment were able to don the masks properly. "There were a couple of errors that were very common," says Kristin Cummings, of the National Institute for Occupational Safety and Health. "One was not tightening up the nose clip," she says. That's the metal strip at the top of the mask that should be adjusted to fit the contour of your nose. Another mistake: 22 percent of people put the mask on upside down.
To help you properly wear an N95 respirator:
Here are printed instructions (3Mb .pdf) about how to put on and take off a respirator - from the U.S. Centers for Disease Control and Prevention (CDC).
Here's a CDC video demonstrating how to wear a respirator.
Here are printed instructions (300Kb .pdf) about how to put on a respirator - from the American Thoracic Society.
Secondary advantage
In addition to trapping or filtering viruses, facemasks and respirators have the advantage of keeping you from touching your mouth and nose - two key areas where the virus enters your body.
Of course, facemasks and respirators should be accompanied by good hygiene. Wash hands frequently (for 20+ seconds) ... use a hand sanitizer when you can't wash ... and cover your coughs/sneezes.
You can also get the flu by touching contaminated surfaces and then touching your hands to your mouth and nose. That's another reason for frequent handwashing with soap and water or using hand sanitizers.
