Exhaled SARS-CoV-2 aerosol infectivity enables Covid-19 transmission in minutes | Hacker News Reader

Exhaled SARS-CoV-2 aerosol infectivity enables Covid-19 transmission in minutes

nature.com

34 pointsbookofjoe29 comments

My family wore 3M's best face masks for the US market, i.e., N95, and we still got it a few times. We switched to FFP3, equivalent to N99, and there have been no infections so far.

I am surprised how bad people are at basic arithmetic! A N99 face mask is 5 times better than a N95 one, not just 4% better!

So, I wonder why FFP3 is only available in Europe. I buy the FFP3 face masks, which are manufactured in Poland, from a UK online retailer, but this is sad, given that 3M is an American company.

Those are absolutely not 3M's best face masks, if you want half face and low profile the 650X (6502 is medium) elastometic respirator is good, when combined with P100 filters, if you want full face you could look to see if they still sell the CBRN hardened respirator and filter sets.

Of course these types of respirators have an exhalation valve and would be a dick move to wear anywhere that requires masks. If you’re contagious you’ll be spewing virus all over just like someone with no mask on.

On the other hand, if it prevents you from getting infected in the first place...

There are half-mask respirators with “source control”.

It's only a "dick move" if anyone else actually cares, Zvi's analysis mid 2022 said it would almost never matter, and if it would the other person will tell you.

I wore P100 and FFP3 elastomeric respirators at various times pre-vaccine during the pandemic in California and Europe, as did several of my relatives. Places that understood the problem did care, and many hospitals and medical centres did not allow them for specifically this reason, for example; some accepted them if they were modified to have a filter over the vent, others did not. Most would tell you in advance, but some would not. I came to carry non-vent FFP2s with me as a result, particularly after being harassed by the TSA over it (I suppose they didn't have anything better to do, as I was literally the only passenger going through security at the time, in a major international terminal).

With that said, views on higher spec masks were very arbitrary throughout the pandemic. In one particularly weird case, my partner left a state-run testing centre in Ireland when she arrived with an FFP3 respirator and the staff demanded that she and everyone else wait in poorly ventilated spaces while wearing loose fitting surgical masks they provided because then everyone could be confident everyone was wearing the same masks...

Right, but that's not rational. Especially as of mid 2022 and later, if you want to protect yourself, get a comfortable elastomeric P100 respirator (or SCBA or P100/HEPA PAPR or P100/CBRN gas mask).

10 FFP3 masks from Amazon UK delivered to U.S. cost $30.24 — just ordered them:

https://www.amazon.co.uk/FFP3-Masks-Pack-Filtration-Efficien...

Thank you VERY MUCH for your comment; I had NO IDEA FFP3 masks are so much better than N95 — and I am a (retired) anesthesiologist who knows a thing or three about masks.

I wonder why FFP3 masks aren't made here in the U.S.

Because it's an EU standard. I guess N99 would be similar in the US?

Yes. And we have N100 as well which filter 99.97% of the hardest-to-block particles.

Because FFP3 is a European standard, and you can buy N99 or P100 masks in the US?

3M does not sell in America any disposable face masks above the N95 grade. There are some that are valved, but they are unfair as I don't want to infect others as much as I want others not to infect me.

It's because ffp3 is a European standard. They're terrible to wear though. I'm glad COVID is over and I only ever wore the absolute minimum required. Only got it once during the mask mandate and that's when I didn't actually wear it in a crowded bar (nobody did so there was no point). I only sniffled for 2 days anyway.

Covid over? Not a chance. Still here, still contagious as ever. Media brainwashing may be over, wealth transfer maybe over - Covid no. I have had it 3 times. Every time around 5 days after an international flight with no mask. Mask for me in future and maybe even in the supermarket.Five days in bed I can not afford!

It's not over, and it will never be over if we don't admit that it's here and still killing people, witnessed by the excess mortality. We're like an ostrich with a head in the sand!

But there's so many things killing people. And the people it kills now are so weak they will die rather soon from something else if not covid. They'll get a cold, a food poisoning or whatever else comes our way in normal life.

Here in Holland there aren't even any patients in ICU with covid anymore.

Over as a risk to society I mean.

I'm fully expecting to get it many times. It's just unavoidable. Wearing a mask just reduces the chances of getting what is now a light inconvenience.

For what it's worth I've never even been bedridden by covid. Once I sniffled a bit for a day or two, the one weird thing was that it wasn't in my usual hayfever season. The other time I had a bit of a headache and things tasted funny for a day.

But anyway I do a lot of things in my life that are way way riskier (including from a disease point of view) than getting covid so at this point there's just no more need to worry about it. It's just not in the top 30 things that are most likely to kill me anymore.

I don't worry so much about being overweight, about who I kiss, about exposure to pollution, about climbing steep slopes, about crossing the road even. These things are now way way more likely to kill me or make me sick than covid.

>They're terrible to wear though.

I'm glad I went "full nerd" early and got a PAPR pollution mask.[1] I estimate I'm getting essentially the same 99% protection, except without the hot stuffy sensation.

The CO2 increase is real, despite propaganda to the contrary. This isn't because a mask "blocks oxygen" (duh), it's just because you're re-inhaling a larger volume of exhaled air, beyond the normal mouth/nose+trachea+unused lung volume.[2]

[1] https://www.amazon.com/BROAD-Purifiers-Rechargeable-Respirat...

[2] https://en.wikipedia.org/wiki/Dead_space_(physiology)

CO2 exposure reduces IQ and complex cognitive thinking significantly...

Yes it really bothers me, the re-inhalation. This is why I wore simple FFP1 masks. I found them even better than cloth masks.

Doesn’t every additional infection also reduce the likelihood of you getting it again or even noticing you got it as it gets milder?

If I hadn't tested I would not have guessed that the mild cold I just got was my second covid infection. My first covid infection was quite bad even with 3 vaccinations.

I get palpitations after each infection for at least 4 months. Severe ones, sometimes several per minute. But the worst was after the Pfizer vaccine. I doubt any cardiovascular inflammation could be considered light. Not all people suffer equally, but this is no flu. If you look at excess deaths, it's no joke, and they follow the curve of COVID-19 deaths pretty closely, so it's just undiagnosed COVID-19 deaths, literally.

I’ve experienced the same and paired with my anxiety, I get really uncomfortable it interferes with my day to day life. I’ve visited a couple cardiologists, both well regarded, and been told it could be inflammation and to ignore it unless its painful and to get more fit (BMI fine, but a bit sedentary). But I feel the medical community is lagging behind in this regard, sadly. Oh, and masks didn’t make much of a difference anecdotally here.

From what I've seen the filtration level between FFP2/N95 and FFP3/N99 doesn't make that much of a difference when it comes to covid.

Fit does.

The problem is the air going around the mask and through the seals, bypassing the filter entirely. As for the 99/95 in N99/N95, it is the percentage of filtration for a specific size of particle in controlled conditions, which may not be how effective it is at filtering virus aerosol particles. The N99 will most likely do better, but by how much? Just because the number suggest a 5x improvement doesn't mean it will be a 5x improvement, and all that is useless anyways if it leaks like crazy because of a bad fit.

But assuming the masks really are the reason for your lack of infections, maybe these FFP3s are simply a better fit. It is very possible as people have different faces.

I can tell you that the materials of the two 3M masks are vastly different. The fit virtually is the same. In fact, the N95 has a slightly better fit as it doesn't use those faulty red rubber bands that the FFP3 does - it has a tighter pull by using a woven elastic cord instead.

There are two spots for leakage - the nose fit and the neck, but both do a great job and come with a tab for the neck so that you can adjust if it gets loose.

OTOH the seal for the 3M N100 is really quite superior over the N95’s and N99’s (effectively making it a different fit). Though it’s valved, so it only filters inhalation, not exhalation.

> Calculations with an indoor air transmission model showed that if an infected individual with this emission rate entered a room, a susceptible person would inhale an infectious dose within 6 to 37 min in a room with normal ventilation.

If this model were accurate, the R would be way higher. So it seems likely that this model misses important aspects.

That's not necessarily true, I have a feeling that I can't really back up that ~all infectious respiratory diseases are airborne (i.e. the infectious particles travel between rooms and linger in common settings), but some combination of infection routes, innate and learned immune responses (actually quite fuzzy when you look at them closely), and human behavior (e.g. "alternate explanations" that epidemiologists come up with like sneezing/coughing) explain why most people don't believe that's the case.

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