[trhway]

>a homemade face mask

and that highlights the main reason of our situation - total lack of organized massive development, production and distribution of masks, tests, etc. Next - a homemade coronavirus test to be self-administered before going "out in public near other people."

The majority of the homemade stuff (until correctly made from material certified for the role) will block the large droplets, yet it wouldn't block much of the micro-droplets, the aerosol, which is what carries the virus for the distance. And once the mask gets wet one can see how it can become a machine for spreading the virus by way of your exhale aerosolizing the virus carrying moisture mass that got accumulated on the mask as result of catching of the large droplets earlier. Ever seen a bubble maker toy?

[chadlavi]

Homemade masks are quite obviously a stopgap until better materials are in place. It feels pretty clear that the original comment was meant to say people should take responsibility for preventing themselves from becoming a vector.

[oski]

Thanks for backing me up, but if the goal is to prevent asymptomatic transmission, homemade masks made from common materials like cotton and paper towels can be 99% effective at preventing _egress_ of respiratory droplets.

The goal of wearing masks is to stop people from spreading their germs, effectiveuly bringing down the R0 value of the virus, slowing the spread, flattening the curve.

The real challenge is that we need about 80% of people to wear masks to really put a dent in things. Really, everyone should be advocating for everyone they know to wear a mask.

See this site for research backed info if you are not convinced: https://www.fast.ai/2020/04/20/skeptics-masks/

[jph00]

I wrote that - thanks for sharing! :) And also wrote this one with Professor Trish Greenhalgh CBE: https://www.fast.ai/2020/04/13/masks-summary/ . Our work on this is getting some attention now in the global medical community; e.g. Martin McKee (Prof of European Public Health LSHTM/ Director Research Policy European Observatory. Past President The European Public Health Association) just tweeted:

"an those speaking about face coverings & #COVID19 please read @trishgreenhalgh evidence review. We are talking about CLOTH FACE COVERINGS not surgical masks Coronavirus IS NOT influenza - coverings work better People spread when talking, NOT JUST COUGHING & when PRESYMPTOMATIC"

I'm so happy to see the progress being made on this issue. 11 out of 12 of the largest countries by GDP now recommend public mask wearing (the other is UK, which is about to change their guidance.)

[hanniabu]

> I wrote that - thanks for sharing!

Question, did you happen to just stumble upon this thread? Or were you using some type of notification service and alerted about it?

[brongondwana]

There's two types of notification service (hi Jeremy, nice to see your work still getting lots of attention) - one is a technical thing, and the other is friends.

Way back a couple of jobs before I worked with Jeremy at Fastmail we used to talk about "slashdot distance", as in "I don't read Slashdot, I just read summaries". "I don't even read summaries, I just have friends tell me if there's anything interesting in the summaries"... etc.

[martingoodson]

That site selectively quotes the literature and misrepresents the scientific record. See here https://rssdss.design.blog/2020/04/24/the-effectiveness-of-c...

[chadlavi]

Thanks but I don't understand why you commented back as if you're disagreeing with me? I agree with all of this.

[oski]

Sorry I was just clarifying that we don’t need to wait for better materials. Homemade masks from common materials, when enough of the population (>80%) uses them, can get us where we need to be.

[literallycancer]

You are unlikely to get exposed to aerosols as a regular person, unless working with high speed and/or rotating equipment. Look up a list of aerosol generating procedures.

[RandomBacon]

What about coughing and sneezing? I still see people (yesterday) in public either sneezing into their hand (not elbow) or not covering their mouth at all.

[trhway]

You're plainly wrong.

https://respiratory-research.biomedcentral.com/articles/10.1...

"Exhaled air is an aerosol containing endogenously generated droplets."