A few ASTM level 3 surgical masks were tested. Worn without modification, they had a filtration efficiency of 35-78% (via particle counter).
(Side note- don’t twist the ear loops- it makes the fit worse)
Is > 20% leak well-fitting? Not in my books.
2/
Jan 8 • 8 tweets • 4 min read
Looking for a #BetterMask but:
✖️N95s are harder to find than TP in 2020
✖️you can’t afford N95s and your government isn’t making them accessible
✖️your workplace mandates medical masks and doesn’t allow N95s
✖️your school gives students medical masks
This 🧵‘s for you
1/
Ensure your medical mask is ASTM graded and is at least a grade 2 mask, preferably grade 3 (will ensure better filtration performance of the mask material)
Important to note, ASTM 3 does not imply or guarantee respirator-quality filtration performance.
2/
Dec 19, 2021 • 15 tweets • 5 min read
To the experts insisting “N95s are useless if not fit-tested”
Have you ever tried to fit test a “well-fit surgical mask” or “3 layered well-fit cloth mask”?
TLDR they are inferior.
A brief case series and 🧵
1/15
There are two type of fit tests, 1) quantitative fit testing - a portacount machine measures the concentration of aerosol outside the mask versus inside the mask and 2) qualitative fit testing - a potent bitter or sweet aerosolized solution is inhaled under a hood
When the science and our understanding evolves, it’s important to communicate this clearly and concisely to the public rather than fall back on nuance and shades of gray. Even when this means admitting that previous messaging was incorrect.
May 1, 2021 • 4 tweets • 3 min read
I wear an N95 respirator to protect myself, my patients, my colleagues and my family. Blocking inhalation and exhalation of potentially infectious particles just makes sense during a respiratory pandemic. #PerfectFit on the PortaCount #SayNoToSafetyStewardship#FreshAirWeCare
Because a fit factor of 5 (20% leak) - when quietly breathing through a surgical mask - isn’t respiratory protection. #BewareOfMaskNostrils #BYOPPE
Apr 15, 2021 • 4 tweets • 1 min read
“During the great COVID pandemic of 2020, you may be shocked to learn that many international ID experts believed that respiratory viruses spread primarily through fomites and eyes, rather than the more obvious route - inhalation...”
“As the pandemic swept across the globe, and cases grew, so did the evidence supporting aerosol transmission. The increased risk in shared indoor air and poorly ventilated spaces and decreased risk outdoors was plain for all to see.”
Mar 25, 2021 • 4 tweets • 1 min read
Review of available evidence supporting fomites transmission
TLDR: there is no evidence
f1000research.com/articles/10-233
Current IPAC policies are heavily weighted towards preventing droplet/fomites spread and active nosocomial outbreaks are blamed on HCWs for not tying gowns correctly, other donning/doffing errors, not wearing proper face shield, etc