📍~100% of tiny particles (<0.1μm) through Brownian diffusion
📍~100% of the larger particles (>1.0μm) through interception
📍medium particles (~0.3μm) are trickier but an N95 mask will still filter out 95% of these.
To understand this in more detail, this brilliant video from @minutephysics explains the genius physics behind N95 masks and how they work to protect you against even the tiniest fine particles.
TLDR: They work more like magnets than like sieves.
There are a number of mechanisms in action within N95 masks which contribute to their filtration efficiency, including:
Oh, and just in case you’re getting confused about all the mask terminology (N95, N99, FFP2, FFP3 etc), this is a really useful explainer from the good folks @SmartAirFilters:
Broadly speaking, an N95 is similar to the European FFP2 standard.
To anyone paying attention, these illness absence figures should not come as a surprise.
By early December, UKHSA was warning about how flu was spreading like wildfire through classrooms, leading to very high infection rates in school-age children (pink & green lines on chart).
“When it comes to flu, the focus is often on droplet transmission, but there’s also evidence of aerosol transmission. That means that ventilation & air filtration are HUGELY important.
“Are the Govt looking to improve that to help deal with all the respiratory infections?”
On the BBC News this evening, Medical Editor @BBCFergusWalsh clearly stated:
“As for facemasks, simple surgical masks are *not* good at stopping viruses. You really need a properly fitted tight respirator mask for that”…
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…which begs the question, why does the NHS infection control guidance STILL only recommend surgical masks for treating patients with airborne viruses like flu & Covid… and not proper FFP3 masks?
Even Baroness Hallett was rather perplexed by this during the Covid Inquiry.
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The IPC experts (Dr Warne & Dr Shin) who provided independent specialist advice to the Covid Inquiry both stated that IPC guidelines should be updated to recommend routine use of FFP3 masks when caring for patients with ANY respiratory virus.
1️⃣ He only mentions that people who are sick “must wear a mask in public spaces”…
…but why did he not also suggest that people who are *not* sick should wear a mask to prevent themselves getting sick in the first place?!
Like this ⬇️
2️⃣ Why didn’t @danielelkeles mention FFP masks?
Surgical masks DON’T protect against airborne transmission of flu.
“Live viruses could be detected in the air behind ALL surgical masks tested. By contrast, properly fitted respirators could provide at least a 100-fold reduction.”