Thread by @CorsIAQ

1/ Beware - A lot of uneducated and misinformed (at best) garbage being disseminated by those who do not want others to wear masks to reduce their inhalation exposure to virus-laden respiratory aerosol particles.

2/ Masks do not act like sieves with openings too big to capture some particles or small enough to capture others. Filtration mechanisms are more complex than this and have been well defined on this medium many, many times in the past by those educated on the topic.

3/ This is a good not-too-technical summary for those inclined to want to understand the filtration mechanisms of gravitational settling, impaction, interception, Brownian motion (sometimes referred to as diffusion), and electrostatic attraction. airpophealth.com/blogs/air-reso…

4/ There is always a minimum capture efficiency (often between 0.2 and 0.4 um), where there is a penetration (get through filter) sweet spot with respect to the mechanisms defined above. Particles with smaller diameters are more effectively filtered due to Brownian motion..

5/ The filtration efficiency increases above the diameter of minimum efficiency because of increased combination of interception, impaction, and gravitational settling (for larger aerosol particles).

6/ Another bit of misinformation relates to the size of viruses somehow affecting filtration. Viable SARS-CoV-2 or other airborne infectious viruses do not leave the human respiratory system as a naked virus.

7/ Viruses leave the respiratory system embedded in respiratory aerosol particles (their effective ride share into room air.

8/ These respiratory aerosol particles (RAPs) are generated by mechanical actions from the deep lungs to mouth. For those who actually want to learn more about RAP generation, this is a good paper and Figure 1 provides an excellent summary - nature.com/articles/s4225…

9/ Respiratory aerosol particles in which viruses are embedded contain salts and proteins associated with mucous, etc., span a wide range of diameters and shrink to some extent when leaving the human body as the water phase of the aerosol evaporates.

10/ Note that a a 2 micron diameter particle has a volume that is approximately 5,000 times that of a SARS-CoV-2 virus.

11/ What's important is not trying to filter a virus with a 0.12 micron effective diameter, but rather the RAPs that the virus is embedded in & that have a spectrum of larger diameters (if they are conveying the virus).

12/ A well-fit N95 respiratory will remove well over 95% of the respiratory aerosol particles that convey the SARS-CoV-2 or other airborne infectious viruses through air. This will provide a HUGE reduction in inhalation exposure and huge reduction in probability of infection.

13/ I hope this helps folks who care about reducing their chances of getting COVID-19 and who are confused by those intentionally or unintentionally providing misinformation about masks, filtration of viruses in masks, etc. We are in a surge, folks. Be smart and stay safe..