Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Airflow filtration efficiency (percent activity exhaled ± CI) with test mask placed on the source and Masks sealed and unsealed. N95 (3M respirator), SMnat (surgical mask looped naturally around the ears), SF (SecureFit™ Ultra Fitted surgical mask), and PT (SecureFit™ Ultra Fitted surgical mask with nanofiber filter media).
