Responding to what it says are “incorrect claims” that N95 respirators are not effective against the virus that causes Covid-19, the U.S. Department of Labor’s Occupational Safety and Health Administration (OSHA) released an FAQ that explains why an N95 respirator is effective at protecting users from the virus.
“’N95’ refers to a class of respirator filter that removes at least 95 percent of very small (0.3 micron) particles from the air,” the communication states. “Some people have mistakenly claimed that since the virus that causes COVID-19 is approximately 0.1 microns in size, wearing an N95 respirator will not protect against such a small virus. That mistaken claim appears to result from a misunderstanding of how respirators work.”
OSHA says the respirator filters the virus when it is expelled by a sick person because the virus is attached to larger particles such as water and mucus. OSHA also explained additional ways the respirators work to capture particles.
“An electrostatic charge also attracts particles to fibers in the filter, where the particles become stuck. In addition, the smallest particles constantly move around (called “Brownian motion”), and are very likely to hit a filter fiber and stick to it.”