A short thread on how face masks work, why we wear masks *to protect other people from ourselves* and not the other way around, & why wearing face-shields without a mask, masks with valves, or masks that hang open on the bottom or sides IS ACTUALLY DANGEROUS FOR EVERYONE ELSE...

I am going to start off by citing from a great paper by @trishgreenhalgh about the benefits of mask wearing, which you can read in full here: https://t.co/l0NfuU85cZ
Masks can work in 2 ways: protecting the wearer, & protecting other people from exhalations emitted by the wearer. Surgical grade masks are supposed to do both. They block out small particles emitted by the source, AND they filter those particles out from other emissions
For cloth masks, however, they are not so good at filtering out tiny particles which can contain viruses. But what they are good at doing is limiting the large droplets people give off when they breathe or cough – before they become aerosolised.
This means when you wear a cloth mask, the most important role that it plays is not protecting you from other people's exhalations but *protecting them from yours*. @trishgreenhalgh calls this 'source control' i.e. 'protects other people from droplets emitted by the wearer'
Unfortunately most people seem to think they are wearing a mask to protect *themselves* from everyone else. Which, unless you are wearing a fancy medical mask with a fancy rating, is not only selfish but also incorrect.
What cloth masks are supposed to do is filter the air you breath out, right at the source. This blocks large droplets as they are emitted, before they can become smaller aerosols (which are harder to block & can more easily make their way through another person's cloth mask)
Early on, when people were (mentally) struggling to breath with a mask on, lots of people bought & sold masks with vents. This meant what the wearer breathed in was filtered, but what they breathed out (via the vent) was not. So, no source control.
The same goes for these terrible 'half face shields' now on sale, that cover the nose & lower part of the face with clear plastic but are *open at the bottom*. This actually means both inhalations AND exhalations are not filtered by anything. You might as well not wear anything.
the same applies if you have a mask – even a medical grade one – that does not fit or is not properly tied, and has gaping holes under the chin, above the cheeks, or on the side of the face. If there are gaps where air can get in or out, your mask is pointless and even dangerous.
Masks made using only one layer of fabric – like buffs – are also not great at doing anything except making it look like you are wearing a face cover. Which is why most medical centres etc won't accept them. They are ok-ish for exercising outdoors, and can be worn by kids.
Face shields by the way have similar flaws *as masks* (which they are not, which is why they *must be worn together with a mask* and are not sufficient on their own). Shields are barriers not filters, and may protect the eyes, eg.
Bottom line:
The reason you wear a mask because *you* could be a source of SARS-CoV-2.
If you wear masks that allow your breath to leave unfiltered by layers of cloth, you may as well not even wear one.
Please, for all of our health, wear a proper mask and wear it properly
Also, thank you to @trishgreenhalgh who has been sharing and publishing this knowledge for nearly a year, and for all the other medical professionals who have been doing everything they can to teach us about *why* and *how* masks work to protect other people.

More from Society

The UN just voted to condemn Israel 9 times, and the rest of the world 0.

View the resolutions and voting results here:

The resolution titled "The occupied Syrian Golan," which condemns Israel for "repressive measures" against Syrian citizens in the Golan Heights, was adopted by a vote of 151 - 2 - 14.

Israel and the U.S. voted 'No'
https://t.co/HoO7oz0dwr


The resolution titled "Israeli practices affecting the human rights of the Palestinian people..." was adopted by a vote of 153 - 6 - 9.

Australia, Canada, Israel, Marshall Islands, Micronesia, and the U.S. voted 'No' https://t.co/1Ntpi7Vqab


The resolution titled "Israeli settlements in the Occupied Palestinian Territory, including East Jerusalem, and the occupied Syrian Golan" was adopted by a vote of 153 – 5 – 10.

Canada, Israel, Marshall Islands, Micronesia, and the U.S. voted 'No'
https://t.co/REumYgyRuF


The resolution titled "Applicability of the Geneva Convention... to the
Occupied Palestinian Territory..." was adopted by a vote of 154 - 5 - 8.

Canada, Israel, Marshall Islands, Micronesia, and the U.S. voted 'No'
https://t.co/xDAeS9K1kW
Brief thread to debunk the repeated claims we hear about transmission not happening 'within school walls', infection in school children being 'a reflection of infection from the community', and 'primary school children less likely to get infected and contribute to transmission'.

I've heard a lot of scientists claim these three - including most recently the chief advisor to the CDC, where the claim that most transmission doesn't happen within the walls of schools. There is strong evidence to rebut this claim. Let's look at


Let's look at the trends of infection in different age groups in England first- as reported by the ONS. Being a random survey of infection in the community, this doesn't suffer from the biases of symptom-based testing, particularly important in children who are often asymptomatic

A few things to note:
1. The infection rates among primary & secondary school children closely follow school openings, closures & levels of attendance. E.g. We see a dip in infections following Oct half-term, followed by a rise after school reopening.


We see steep drops in both primary & secondary school groups after end of term (18th December), but these drops plateau out in primary school children, where attendance has been >20% after re-opening in January (by contrast with 2ndary schools where this is ~5%).

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राम-रावण युद्ध समाप्त हो चुका था। जगत को त्रास देने वाला रावण अपने कुटुम्ब सहित नष्ट हो चुका था।श्रीराम का राज्याभिषेक हुआ और अयोध्या नरेश श्री राम के नेतृत्व में चारों दिशाओं में शन्ति थी।
अंगद को विदा करते समय राम रो पड़े थे ।हनुमान को विदा करने की शक्ति तो राम में थी ही नहीं ।


माता सीता भी हनुमान को पुत्रवत मानती थी। अत: हनुमान अयोध्या में ही रह गए ।राम दिनभर दरबार में, शासन व्यवस्था में व्यस्त रहते थे। संध्या को जब शासकीय कार्यों में छूट मिलती तो गुरु और माताओं का कुशल-मंगल पूछ अपने कक्ष में जाते थे। परंतु हनुमान जी हमेशा उनके पीछे-पीछे ही रहते थे ।


उनकी उपस्थिति में ही सारा परिवार बहुत देर तक जी भर बातें करता ।फिर भरत को ध्यान आया कि भैया-भाभी को भी एकांत मिलना चाहिए ।उर्मिला को देख भी उनके मन में हूक उठती थी कि इस पतिव्रता को भी अपने पति का सानिध्य चाहिए ।

एक दिन भरत ने हनुमान जी से कहा,"हे पवनपुत्र! सीता भाभी को राम भैया के साथ एकांत में रहने का भी अधिकार प्राप्त है ।क्या आपको उनके माथे पर सिन्दूर नहीं दिखता?इसलिए संध्या पश्चात आप राम भैया को कृप्या अकेला छोड़ दिया करें "।
ये सुनकर हनुमान आश्चर्यचकित रह गए और सीता माता के पास गए ।


माता से हनुमान ने पूछा,"माता आप अपने माथे पर सिन्दूर क्यों लगाती हैं।" यह सुनकर सीता माता बोलीं,"स्त्री अपने माथे पर सिन्दूर लगाती है तो उसके पति की आयु में वृद्धि होती है और वह स्वस्थ रहते हैं "। फिर हनुमान जी प्रभु राम के पास गए ।