‘We’ve all become familiar with the value of surgical face masks in both preventing infection or, in the case of an already infected person, in preventing further spread of the disease. The masks essentially filter the air coming in and out of the lungs, trapping the virus and other particles in its mesh. Through the COVID-19 crisis, many have become familiar with N95 masks, which filter out 95 percent or more of small particulate matter from the air — including the virus.

But in filtering those particles, the mask also makes it harder to breathe. N95 masks are estimated to reduce oxygen intake by anywhere from 5 to 20 percent. That’s significant, even for a healthy person. It can cause dizziness and lightheadedness. If you wear a mask long enough, it can damage the lungs. For a patient in respiratory distress, it can even be life threatening.

“Someone wearing an N95 mask for a prolonged period of time may have alterations in their blood chemistry that could lead to changes in level of consciousness if severe,” said infectious disease expert Amesh Adalja, M.D., of Johns Hopkins Center for Health Security in Maryland. He told Health that this would most likely happen to people who are smokers, overweight, older people, or others who have respiratory conditions.

He added that there is no reason for the general public to even be wearing N95s.’

COVID-19 research Stanford Engineering 
Safety masks