The first four comments when I got here were disparaging this tweet chain and saying masks don't work. I did a bit of research and found multiple articles claiming masks DO work.

These sources acknowledge that masks are a contentious point and that some experts disagree with the part of the articles I am quoting below. Even the CDC recommends against members of the public using respirators without specific risk factors (having Covid, or treating someone with Covid). The CDC wants to prevent hoarding, as they should.

But many sources claim that a homemade mask from a spare vacuum bag or dish rag makes you a bit safer (2-5x safer than nothing), and I'm going to make one for myself and use it when going out. From the overall body of evidence, I believe that masks are substantially better than nothing, and a social norm of everyone wearing masks would lower Covid transmission. If you disagree provide sources and reasons.

>Wearing a face mask is certainly not an iron-clad guarantee that you won’t get sick – viruses can also transmit through the eyes and tiny viral particles, known as aerosols, can penetrate masks. However, masks are effective at capturing droplets, which is a main transmission route of coronavirus, and some studies have estimated a roughly fivefold protection versus no barrier alone (although others have found lower levels of effectiveness).[0]

>The public doesn't need to wear heavy-duty respirators, but it's a smart idea to don a face mask or wrap a clean scarf around your nose and mouth if you're going into a crowded place during the COVID-19 outbreak, an infectious disease doctor told Live Science.[1]

Even the CDC agrees that "The role of facemasks is for patient source control, to prevent contamination of the surrounding area when a person coughs or sneezes. Patients with confirmed or suspected COVID-19 should wear a facemask until they are isolated in a hospital or at home. The patient does not need to wear a facemask while isolated." [2]

Other articles agree that sick people wearing face masks helps prevent them spreading to others, e.g., [3]

I have read sources that Covid19 can be transmitted even if you have no symptoms. So if everyone wears face masks, then everyone who is infected with no symptoms will have a reduced chance of transmitting the virus. Unlike social distancing and lockdowns, masks have almost no downside. Why are we not heavily promoting masks for anyone going out of the home!?

HN generally loves the NYTimes, great article: [4]. Homemade masks aren't perfect, but the article explains that "of course masks work — maybe not perfectly and not all to the same degree, but they provide some protection. Their use has always been advised as part of the standard response to being around infected people, especially for people who may be vulnerable."

I encourage everyone reading this to consider making a mask out of an item you already own and wearing it when leaving the house.

[0] https://www.theguardian.com/world/2020/mar/23/can-a-face-mas...

[1]https://www.livescience.com/coronavirus-do-face-masks-work.h...

[2]https://www.cdc.gov/coronavirus/2019-ncov/hcp/respirator-use...

[3]https://www.cedars-sinai.org/newsroom/covid-19-for-most-mask...

[4]https://www.nytimes.com/2020/03/17/opinion/coronavirus-face-...