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Why masks with valves do not slow the spread of COVID-19 (1 of 2): Video Transcript (Including Description of Visuals)
[0:00 – 0:07] We see a callout box with text that reads, "NOTE: This high-speed visualization shows airflow when wearing an N95 mask with and without an exhalation valve. It does NOT show movement of virus particles."
[0:08 – 0:31] We see side-by-side images of a man with safety glasses and mask, breathing normally. Above the images are the words, "airflow visualization 30 fps (frames per second).
The left image features an N-95 mask with a valve and is labeled "Unfiltered breath." This image on the left shows air streaming outward from the valve as the man breathes.
Simultaneously, the right image features an N-95 mask without a valve and is labeled "Filtered breath." This image shows a soft plume of air escaping from the mask as the man breathes.
Text reads, "The CDC recommends that people wear masks in the public to slow the spread of COVID-19. However, masks with exhalation valves allow exhaled breath to escape unfiltered. Cover smart. Do your part. Slow the spread.
Read the accompanying news story.