N95 face masks

 "The N95 is the most recognizable and effective mask. Its name means it can block at least 95 percent of tiny particles — 0.3 microns — that are the hardest to capture. An average human hair is about 70 to 100 microns wide.

These masks, which are designed for single use, are made with polyester and other synthetic fibers, including layers of tangled fibers that act as a filter to make it harder for particles to pass through.

Make sure there are no gaps between the edge of the mask and your skin.

This one mask includes a nose piece that is molded to your face. Many health care and other workers do annual fit tests that check for air leakage and ensure that masks are sized and fit properly. (If you have facial hair, you won’t get a proper fit. They don’t fit well on children, either.)

Some N95s have exhalation valves on the front, which make it easier to breathe. Those masks are often used in construction. A mask with a valve should not be used in areas that are meant to be sterile, like hospital operating rooms."

 When inhaling, the mask should fit more snugly against your face. This indicates that there are no large cracks. If you go to the store with such a mask once a week, you can dry that mask all week. During such drying, the virus itself will lose its biological activity, and nothing else needs to be done. If you can, do not go around all day long with one mask on your face. The mask gets wet in hours.