Rescue officer carrying an axe during the aftermath of the September 11 terrorist attack on the World Trade Center, New York… https://www.rawpixel.com/image/3978599/photo-image-paper-face-mask-smokeFree Image from public domain licenseN95 type face masks or respirators. Original image sourced from US Government department: Public Health Image Library… https://www.rawpixel.com/image/2288512/free-photo-image-mask-face-coronavirusFree Image from public domain licenseRescue operations during the aftermath of the September 11 terrorist attack on the World Trade Center, New York City.… https://www.rawpixel.com/image/3978606/photo-image-paper-face-mask-smokeFree Image from public domain licenseRescue officers wearing N95 mask during the aftermath of the September 11 terrorist attack on the World Trade Center, New… https://www.rawpixel.com/image/3978604/photo-image-paper-face-mask-smokeFree Image from public domain license