This illustrates: 1) importance of masking for source control 2) overdispersed nature of transmission
Top mask worn for ~45 min by person with strong RAT nasal swab, mask tested within 5 min, inside of mask was dry.
1/4
In this N of 2 experiment, the strength of RAT result on standard throat/nasal swab correlated with #MaskRAT result.
The bottom person (me) had multiple negative #MaskRATs and barely detectable nasal/throat RAT for 1 day (day 5)
2/4
An unfortunate finding during my RAT experiments:
My symptomatic children never tested positive on a RAT and I never tested positive on the RATs available in ON.
Without access to PCR testing for kids and case reporting in schools, we’re intentionally flying blind.
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/
For kids and those with smaller faces, try the #KnotTuckTape
Turn that rectangle into something more face-shaped. I think taping the corners is important otherwise the tucked in edges often unfold fairly quickly.
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
2/15
I underwent quantitative fit testing on a surgical mask, suboptimally fit KN95 and well fit CN99 (FFP3). The results were intuitive. The surgical mask, while still offering some protection, performed the worst.
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.
Side tweet - Probably could have saved some pages by omitting the giant shades of gray diagram - not a difficult concept