There are many types of N-95 masks available, but do not use one with an exhalation valve during this pandemic. For those of us not in a medical setting, but just wanting to help prevent the further spread of COVID-19 while in public, particularly as some states ease up on stay-at-home orders, a face covering is a very important public health procedure when outside your home.
The purpose is not so much to protect the person wearing a mask or scarf, but to prevent the wearer, who may be infected with COVID-19 but have no symptoms, from spreading the disease. And it does not require a cough or sneeze to spread the virus—talking or just breathing may be sufficient to infect others in close proximity.
The N-95 mask with exhalation valve was designed only for industrial use and never authorized for use in a medical setting . It does a great job preventing small particles from entering the masks, but a really bad job of preventing particles from exiting the masks.
UPDATE: On May 2nd, two reporters on ABC World News Tonight wore N-95 masks with exhalation valves while one wore an N-95 mask more suited to prevent the spread of the virus:
For more information, read this article:
Mark Wilson – What is a Mask Valve and Why are Cities Banning Them – Fast Company