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What are the theoretical reasons why surgical masks might or might not work

Epidemiologists used to sort disease transmission into three categories: contact, droplet, and airborne. Contact means you only get a disease by touching a victim. This could be literally touching them, or a euphemism for very explicit contact like kissing or sex. Droplet means you get a disease when a victim expels disease-laden particles into your face, usually through coughing, sneezing, or talking. Airborne means you get a disease because it floats in the air and you breathe it in. Transmission via “fomites”, objects like doorknobs and tables that a victim has touched and left their germs on, is a bonus transmission route that can accompany any of these other methods.

More recently, scientists have realized that droplet and airborne transmission exist along more of a spectrum. Droplets can stay in the air for more or less time, and spread through more or less volume of space before settling on the ground. The term for this new droplet-airborne spectrum idea is “aerosol transmission”. Diseases with aerosol transmission may be spread primarily through droplets, but can get inhaled along with the air too. This concept is controversial, with different authorities having different opinions over which viruses can be aerosolized. It looks like most people now believe aerosol transmission is real and applicable to conditions like influenza, SARS, and coronavirus.

Surgical masks are loose pieces of fabric placed in front of the mouth and nose. They offer very good protection against outgoing droplets (eg if you sneeze, you won’t infect other people), and offer some protection against incoming droplets (eg if someone else sneezes, it doesn’t go straight into your nose). They’re not airtight, so they offer no protection against airborne disease or the airborne component of aerosol diseases.

Respirators are tight pieces of fabric that form a seal around your mouth and nose. They have various “ratings”; N95 is the most common, and I’ll be using “N95 respirator” and “respirator” interchangably through most of this post even though that’s not quite correct. When used correctly, they theoretically offer protection against incoming and outgoing droplet and airborne diseases; since aerosol diseases are a combination of these, they offer generalized protection against those too. Hospitals hate the new “aerosol transmission” idea, because it means they probably have to switch from easy/cheap/comfortable surgical masks to hard/expensive/uncomfortable respirators for a lot more diseases.

Theory alone tells us surgical masks should not provide complete protection. Coronavirus has aerosol transmission, so it is partly airborne. Since surgical masks cannot prevent inhalation of airborne particles, they shouldn’t offer 100% safety against coronavirus. But theory doesn’t tell us whether they might not offer 99% safety against coronavirus, and that would still be pretty good. Stay tuned to z2u.com and we will be the first one to inform you all the latest. Besides, our website also offer Cheap KN95 Face Masks for players.