Turbulent clouds? oh my! where’s my mask?
Turbulent Gas Clouds and Respiratory Pathogen Emissions
Potential Implications for Reducing Transmission of COVID-19
Turbulent gas cloud dynamics should influence the design and recommended use of surgical and other masks. These masks can be used both for source control (ie, reducing spread from an infected person) and for protection of the wearer (ie, preventing spread to an unaffected person). The protective efficacy of N95 masks depends on their ability to filter incoming air from aerosolized droplet nuclei. However, these masks are only designed for a certain range of environmental and local conditions and a limited duration of usage.9 Mask efficacy as source control depends on the ability of the mask to trap or alter the high-momentum gas cloud emission with its pathogenic payload. Peak exhalation speeds can reach up to 33 to 100 feet per second (10-30 m/s), creating a cloud that can span approximately 23 to 27 feet (7-8 m). Protective and source control masks, as well as other protective equipment, should have the ability to repeatedly withstand the kind of high-momentum multiphase turbulent gas cloud that may be ejected during a sneeze or a cough and the exposure from them. Currently used surgical and N95 masks are not tested for these potential characteristics of respiratory emissions.
https://jamanetwork.com/journals/jama/fullarticle/2763852
Every hotspot has ‘its own curve’: How coronavirus cases are growing around the United States
The seeds came in at different times’
...In CNN’s analysis, the 15-day period starting at the beginning of March saw large daily increases in states such as Washington, California and New York.
But Florida, Georgia, Louisiana and Tennessee only began to see sharply rising numbers in the second half of March. It remains unclear whether those dates reflect the beginnings of actual outbreaks, or stepped-up testing that revealed those outbreaks.
Dr. Deborah Birx, the White House coronavirus response coordinator, acknowledged these varying timelines in a press briefing Monday.
“Each state and each hotspot in the United States is going to be its own curve, because the seeds came in at different times,” said Birx.
“So, Washington state is on their curve they’re about two weeks ahead of New York,” she added.