Amazing to see decent public health advice for once.

All masks are not equal, so it’s great to see Frosty the Snowman here wearing a high quality, well-fitted N95 mask.

#BeLikeFrosty ⛄️

Read on in this thread 🧵 to find out more about the wonders of N95 masks…
The study below compared the fitted filtration efficiency of surgical masks vs N95 masks:

📍Surgical mask: 38.1%
📍N95 respirator: 98.5%

As you can see, surgical masks have vastly inferior fitted filtration efficiencies compared to high quality N95s.

jamanetwork.com/journals/jamai…
Image
The physics of masks is very interesting.

N95’s filter out:

📍~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. Image
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.


Image
There are a number of mechanisms in action within N95 masks which contribute to their filtration efficiency, including:

📍gravity sedimentation
📍inertial impaction
📍interception
📍diffusion
📍electrostatic attraction

You can read more about this here:

sciencedirect.com/science/articl…
Image
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.

smartairfilters.com/en/blog/compar…
Image

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More from @_CatintheHat

Jun 25
The UK is currently sweltering in a serious heatwave.

Over 1,000 schools have been forced to shut or close early due to the extreme heat.

Unsurprisingly, questions have been raised about air-conditioning for schools since heatwaves are likely to become increasingly common…

/1 Image
However, if air-conditioning does get the green light🚦, I just hope those involved in implementation look at the bigger picture.

The thing is, most air-con systems do *not* bring in fresh air from outside.

They simply cool & recirculate the existing air from the room.

/2 Image
And, in order for the air-con to be effective, it’s often recommended to close windows to stop warm outdoor air from flooding in.

BUT, in a practically airtight classroom with ~30 kids all breathing continuously, CO₂ levels will rapidly build up…



/3 the-educator.org/why-air-condit…Image
Read 9 tweets
May 15
🚨“Why COVID could be to blame for the rise in deadly meningitis”

“When people regularly catch Meningitis B bacteria, they usually live harmlessly in the nose.”

“The problem is that COVID may have made our cells more susceptible to the bacteria.”

dailymail.com/health/article… x.com/dailymail/stat…Image
A growing number of scientists have been sounding the alarm recently about how repeated Covid infections may be damaging our immune systems…

bmj.com/content/390/bm…Image
This is not a particularly new idea; it’s been discussed in scientific circles for years already.

Back in early 2023, the World Health Network (@TheWHN) published this article which summarised the latest research on Covid’s impact on the immune system.

whn.global/scientific/cov…Image
Read 9 tweets
May 14
HANTAVIRUS OUTBREAK

A WHO representative was interviewed on GMB this morning.

She said that if someone self-isolating at home starts to feel sick, they should immediately remove themselves from company & start wearing a mask…

…but that’s NOT what the WHO guidance says… 🧵
The guidance is clear that those self-isolating at home should NOT wait for symptoms before taking precautions.

For the ENTIRE 42-day quarantine, they should:
▪️Avoid contact with other household members
▪️Remain in a separate room
▪️If contact is unavoidable, wear a respirator Image
🚨Clinically Vulnerable Families (@cv_cev) have issued a press release calling for the government to immediately publish the full operational & clinical arrangements for passengers & close contacts linked to the MV Hondius outbreak.

Transparency is essential at this point. Image
Read 13 tweets
May 11
HANTAVIRUS OUTBREAK:

I’ve just listened to the health update from the US Nebraska Health Officials 🇺🇸

A few points of interest:

1/ in addition to the US passenger who tested positive & the one showing symptoms, it seems there is ANOTHER passenger who may have tested positive.
2/ Passengers currently in the Nebraska quarantine unit will spend a few days there being assessed.

If they remain symptom free & have support available at home to isolate safely, they’ll have the choice to complete the 42-day isolation either at home or in the quarantine unit.
3/ When asked about the US passengers who left the ship in St Helena on 24 Apr (at the same time at the Dutch woman who was symptomatic & sadly died on 26 Apr), they confirmed that these passengers have all been traced & are being monitored - but seems they’re NOT self-isolating.
Read 10 tweets
May 10
HANTAVIRUS OUTBREAK

Following my thread yesterday which criticised aspects of the WHO’s strategy, I’m pleased to see they’ve done a 180° turn in the updated guidance published today:

who.int/docs/default-s…

EVERYONE from the ship will now be treated as HIGH-RISK contacts…

🧵 x.com/_catinthehat/s…Image
…and ALL high-risk contacts will now be required to ISOLATE in a designated facility or at home (depending on each country’s capabilities) for 42 days from last known exposure…

…and for the MV Hondius passengers & crew, the last day of exposure is the date of disembarkation. Image
So for the passengers & crew leaving the ship today, the clock for their 42 days in isolation starts ticking TODAY…

…and their isolation & monitoring will end on 21 June. Image
Read 7 tweets
May 9
HANTAVIRUS OUTBREAK 🧵

Following the WHO press briefing, I wanted to compile a thread with the key points.

1/ ISOLATION OF PASSENGERS

Concerningly, it seems the WHO are NOT recommending to isolate cruise ship passengers (even high-risk contacts) UNLESS they develop symptoms.
Just to quickly recap, it has been confirmed that the passengers & crew (including the 30 who disembarked on 24 April in St Helena) come from a total of 28 different countries.

The full breakdown of countries for both passengers 🟥 & crew 🟦 is detailed below ⬇️ Image
When the 146 people remaining on the ship are repatriated to their home countries, each country will adopt their own local protocols.

However, the WHO are only recommending:

▪️SYMPTOMATIC cases ➡️ isolation
▪️ASYMPTOMATIC cases ➡️ monitoring
Read 41 tweets

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