It’s all about spit.
Disclaimer: I’m not a medical professional. My advice is not a substitute for professional medical advice.
I normally write about theoretical physics but as a trained scientist, I like to think I can parse most logical arguments. I have been seeing a lot of illogical arguments against mask wearing during the pandemic. Part of it is that different masks are designed for different uses and we aren’t using masks the way that they were designed. Info from the CDC is straightforward but sometimes confusing. But there is another government agency that has been all about masks for a long time.
The U.S. Occupational Safety and Health Administration (OSHA) has regulated standards in work environments, including mask usage, for decades and they have some good information about them.
There are three kinds of masks that people are familiar with
(1) N95 — these are respirator masks that filter incoming air of 95% of particles. They are designed to be used in contaminated environments. They protect the wearer but aren’t designed to protect anybody else. The air you breathe out of them is unfiltered.
(2) Surgical — these are loose fitting masks designed to be worn in sterile environments. They are designed to protect others from you. You breathe in unfiltered air from the sides (and some through the pores in the material) and likewise breath it out.
(3) Cloth — these are just face coverings. They are extremely porous. The holes in them are much, much larger than a virus. They have virtually no filtration properties. They work sort of like a kleenex or handkerchief, blocking mucus and droplets that you expel from your mouth.
It seems like if N95s protect you but not anybody else, surgical masks only work in sterile environments, and cloth masks are so porous they don’t filter the virus, why are we being asked to wear one?
It all has to do with spit.
Here are some of the details from OSHA:
(1) N95 — these protect you but only if you are trained to use them properly. They are not intended to protect others. They “[r]equire proper training, fit testing, availability of appropriate medical evaluations and monitoring, cleaning, and oversight by a knowledgeable staff member.”
(2) Surgical — these protect you from “splashes and sprays (i.e., droplets) containing potentially infectious materials.” They can also protect others by containing “the wearer’s respiratory droplets.” Here is the caveat: they “[w]ill not protect the wearer against airborne transmissible infectious agents due to loose fit and lack of seal or inadequate filtration.” So, unlike the N95, you can’t use these safely in a contaminated environment.
(3) Cloth — they help contain your “potentially infectious respiratory droplets produced when an infected person coughs, sneezes, or talks and to limit the spread of SARS-CoV-2, the virus that causes Coronavirus Disease 2019 (COVID-19), to others.” Basically, they keep your spit in.
The conclusion from this is that you shouldn’t be wearing N95 masks in public. It’s a waste of a good mask. This should only be used in a work setting that is potentially contaminated.
You can wear surgical masks as they have some benefit to you but really only if you use them properly, like taking them off without contaminating yourself and throwing them away after use. If you got infected droplets on them and contaminate your hands or face with it then you aren’t going to be any better off than if you didn’t wear one (probably worse off).
The cloth mask is pretty much like covering your mouth with a handkerchief but with the added benefit that you have it over your mouth and nose all the time, so the amount of spit you expel is reduced a lot. There are a lot of viruses in a drop of spit, so it is worth it.
Conclusion: wear the cloth one unless you need one of the others in a particular setting.
Meta-analysis have shown that face mask mandates can reduce COVID transmission by 50% and have already saved tens of thousands of lives.
A good article on the different studies (instead of just one study) is found here:
Yes, Wearing Masks Helps. Here's Why
Mask wearing has become a topic of fierce debate in the United States. People opposed to mask mandates have staged…www.npr.org
For more information on Occupational Safety and masks, visit OSHA:
COVID-19 | COVID-19 Frequently Asked Questions | Occupational Safety and Health Administration
Cloth face coverings: May be commercially produced or improvised (i.e., homemade) garments, scarves, bandanas, or items…www.osha.gov