A health worker holds an N95 respirator in the emergency room at OakBend Medical Center in Richmond, Texas, in July. N95s are tested and approved by a federal agency as having demonstrated that they can filter out a minimum of 95% of airborne particles.

Bill Hamlyn holds up an N95 mask in the ER at Oakbend Medical Center in Richmond, Texas, on July 15, 2020. – The latest modeling projects the number of COVID-19 deaths in the US to increase further, even as one research team suggests the near-universal use of masks could save 40,000 lives between now and November (Photo by Mark Felix / AFP) (Photo by MARK FELIX/AFP /AFP via Getty Images)