HEPA filters capture particulates. PM2.5 means particles above 2.5 micrometers in diameters. Good 0.2 - 0.3 micrometer HEPA filter is fine enough to catch bacteria like anthrax. Smallpox, influenza virus are smaller. You need carbon absorber to be safe.
HEPA filters capture particulates. PM2.5 means particles above 2.5 micrometers in diameters. Good 0.2 - 0.3 micrometer HEPA filter is fine enough to catch bacteria like anthrax. Smallpox, influenza virus are smaller. You need carbon absorber to be safe.