
Why aren’t we talking more about airborne transmission? - KoftaBob
https://www.theatlantic.com/health/archive/2020/07/why-arent-we-talking-more-about-airborne-transmission/614737/
======
jennyyang
After this pandemic, doctors and scientists are going to have to come up with
more media-friendly terms from now on.

The problem is that "airborne droplets" and "airborne" sound too similar and
it's very hard for regular people to understand what that means. "Airborne
droplets" means that viruses need saliva to transmit between people.
"Airborne" means that the virus only needs dust particles to transmit to other
people. Measles is airborne transmission, which means that if someone with
measles enters a room, that room can be infectious for 12+ hours because
viruses will be infectious in the dust. If someone with coronavirus sneezes in
a room, the large heavy droplets will quickly fall to the ground. If you
breathe in the droplets then you can catch the virus, but these only stay in
the air for seconds. However, there are microdroplets which stay in the air
for 30+ minutes depending on the air currents.

So there is a distinction between them. If coronavirus were truly airborne,
then we would all need to wear masks all the time, even when no one is around.
No where would be safe and we would have to implement extremely strict
lockdowns.

But the fact that scientists and doctors have chosen to use the term
"airborne" in both have made it extremely confusing and given how quickly
information and misinformation is disseminated these days, they need to choose
terms with care from now on.

~~~
jtbayly
> we would have to implement extremely strict lockdowns...

if we assume that the goal is not to flatten the curve but to completely stop
the virus in its tracks. Most people and countries don't have this goal.

Edit: To those downvoting, I'll just say that my statement is factual, so
argue the facts. Long-term, we want a vaccine, yes. In the meantime, most
people and countries are simply not willing to do what it takes to completely
eliminate this virus. They think it would be nice if the virus went away, but
they are not working towards that as their goal.

~~~
jennyyang
If the virus were truly airborne, which it isn't, then simply walking through
an empty room could get you infected. The levels of people getting infected,
and subsequently getting hospitalized would be far worse than the worst scenes
we saw in Italy and NYC. Lockdowns absolutely would have been mandatory for
months upon months.

Coronavirus is not by itself a tremendously deadly disease. The problem is how
infectious it is, and how quickly it can overrun a limited hospital system.
Even at a sub-10% hospitalization rate for people younger than 60, we are
seeing many hospitals getting full. It being truly airborne would make things
worse by many orders of magnitude. The way coronavirus spreads is basically
the same mechanism as the flu and the cold, yet the levels of people getting
infected are much much worse. Imagine if simply walking through a room could
get you infected. The spread would be undeniably worse than anything we had
every seen before. Even stores like Costco and all factories would have to
shut down. So yes, very strict lockdowns would need to be in place.

Thank goodness it's not.

~~~
throwaway_pdp09
> If the virus were truly airborne, which it isn't

why do you say this? The article is saying otherwise, quite literally "The
coronavirus reproduces in our upper and lower respiratory tracts, and is
emitted when we breathe, talk, sing, cough, or sneeze"

> then simply walking through an empty room could get you infected

You're presuming it has to be empty.

If you walked through a full room _without touching anyone or anything_ and
you caught covid, would you accept that it is airborne? Or are you saying that
is impossible?

Do I misunderstand you?

~~~
prox
It’s because it seems to be mostly ballistic droplets, except for a (small?)
percentage were it is not. This is also stated in text for measles (that
spreads throughout a house) which Corona seems to not do.

~~~
throwaway_pdp09
From the article, that's exactly what's being questioned:

"There is a big dispute in the scientific community, however, about both the
size and the behavior of these particles, and the resolution of that question
would change many recommendations about staying safe. Many scientists believe
that the virus is emitted from our mouths also in much smaller particles,
which are infectious but also tiny enough that they can remain suspended in
the air, float around, be pushed by air currents, and accumulate in enclosed
spaces"

~~~
prox
Yes but, and this is the important part : not as potent as for instance
measles (which spreads and infects 90%)

Or we’d see far more indoor cases. And we do see in events with lots of
expiration, where there is singing for example, very potent transmission.

------
R0b0t1
This is a good article.

I work at a biotech company that studies virus transmission and helps others
study it. It was clear from the very beginning that transmission was airborne.
Why would it not be? That the WHO and some doctors were assuming it was not
seriously damages their credibility as healthcare professionals.

Current events should lead people to seriously question deference given to
doctors. They need to be held accountable for their actions and must be made
to listen to professionals in other fields.

~~~
aantix
Why wasn't there a large spike with the recent protests in the participating
demographic?

[https://www.forbes.com/sites/tommybeer/2020/07/01/research-d...](https://www.forbes.com/sites/tommybeer/2020/07/01/research-
determines-protests-did-not-cause-spike-in-coronavirus-cases/)

The chants "no justice, no peace"? "I can't breath"?

Those were clear chants. Everyone breathing on each other while chanting.
Unencumbered by a mask.

~~~
obelos
They're in the extremely well ventilated outdoors, and at least at the
protests I was at there were very few people not wearing masks. Also, people
in these gatherings tend to mill about, which means any contact with a stream
of virus-infused exhalations will be brief and less likely to introduce a
viable quantity into you.

~~~
jakear
I haven’t seen any research on this, but is there a chance being introduced to
very small viral loads could actually improve your expected future health? We
know that larger loads are harder to fight and produce worse symptoms, but
what of “mico-loads”? It would seem they should almost act as a semi-vaccine:
you get an easy to fight and low symptom load once, then you’ve created
antibodies for the future. So long as you continue to be exposed to micro-
loads in day to day life, those antibodies shouldn’t go away, and you’ll be
safe from any potential “mega-load”.

~~~
obelos
I don't know if there's data specific to SARS-CoV-2, but this is the mechanism
behind inoculation (as opposed to vaccination). This method was used to reduce
smallpox deaths before vaccination had been developed.

------
credit_guy
Wow, what a good article. Finally an article in a well respected publication
that goes over the science of the Covid19 transmission, and appears to be non-
partisan as well (what a tragedy that the approach to combat the disease has
become a partisan issue). I really hope this article will, dare I say, "become
viral". If it does, this article by itself could help save tens or hundreds of
thousands of lives.

~~~
martythemaniak
But it won't. The reason things became "partisan" is precisely because things
like the article are useless and ineffective. You're assuming a shared reality
that doesn't exist.

~~~
Loughla
I can only assume you're being downvoted because you've confused the chicken
and the egg.

Partisan issues don't exist because articles like this are useless and
ineffective. Partisan stances on this sort of thing is what _makes people
believe articles like this are useless_. You have it backwards.

I would absolutely agree, though, that there is no such thing as a cultural
'shared reality' anymore. That is the base of the problem. There are very,
very few shared experiences, and a section of the population is not,
seemingly, even interested in trying to understand someone else's viewpoint.

~~~
playingchanges
But the whole point of the chicken and the egg problem is that it is not
apparent which came first.

~~~
happytoexplain
Yes, I think an analogy about a cart and horse was instead called for.

------
mensetmanusman
I am still shocked: months after research has shown that SARS-CoV-2 is
airborne stable in aerosol form for over 3 hours, we still aren’t telling the
public that room air purifiers are a ‘good thing’ (for making indoor air like
outdoor air - in regards to virion density per cubic air volume)

The filter technology is essentially the same as in the N95, orders of
magnitude more effective than cloth masks.

Put these indoors, multiple per classroom/working space to help the air
refresh in sub 5 minute intervals.

~~~
mensetmanusman
Added benefit: post-covid pandemic, improved indoor air quality with all the
included benefits!

Air quality associated with:

Alzheimers: [https://www.scientificamerican.com/article/the-new-
alzheimer...](https://www.scientificamerican.com/article/the-new-alzheimers-
air-pollution-link/)

Cancers, plural: [https://www.aacr.org/patients-caregivers/progress-against-
ca...](https://www.aacr.org/patients-caregivers/progress-against-cancer/air-
pollution-associated-cancer/)

Sperm Quality:
[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4443398/#sec995...](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4443398/#sec99552title)

Female Fertility: [https://www.newscientist.com/article/2207560-exposure-to-
air...](https://www.newscientist.com/article/2207560-exposure-to-air-
pollution-seems-to-negatively-affect-womens-fertility/)

Autism: [https://www.sciencealert.com/particulate-matter-in-air-
pollu...](https://www.sciencealert.com/particulate-matter-in-air-pollution-
raises-autism-risks-in-the-first-few-years)

Bipolar/Depression:
[https://www.nationalgeographic.com/environment/2019/08/air-p...](https://www.nationalgeographic.com/environment/2019/08/air-
pollution-linked-to-bipolar-disorder-depression/)

side note: please make the ICE>Electric transition happen faster... sigh

~~~
heimatau
Thanks for these links. I've saved them for future reference!

------
MiguelVieira
When I look at this heat map of recent cases per capita in the US

[https://globalepidemics.org/key-metrics-for-covid-
suppressio...](https://globalepidemics.org/key-metrics-for-covid-suppression/)

the first thing I see is hot spots all across the southeast and desert
southwest. These places have widely varying governments and cultures, but the
one thing they do have in common right now is: they're hot.

My suspicion is that many of the outbreaks we've seen recently are caused by
people from different households congregating indoors in buildings with air
conditioning and closed windows. The article mentions this, but I rarely here
it talked about on the news:

"The importance of aerosols may even help explain why the disease is now
exploding in the southern United States, where people often go into air-
conditioned spaces to avoid the sweltering heat."

~~~
milesvp
This is something I currently speculate too. Hotter states really benefited
from AC allowing people to live there comfortably. I think it might show us
what’s coming as people move indoors in colder months elsewhere.

It’s getting harder and harder to stay away from people from a purely
psychological standpoint, and I think fall is going to get bad in the PNW as
people congregate indoors to stay out of the wet and cold.

------
j_walter
My company took steps to address this months ago. The re-circulation rate was
set to zero so all air is fresh make up air from outside. This has
significantly increased our cooling bill since it's summer, but it was
something that we felt important even though there hasn't been much science to
back it up. We also have a UV system hooked up to our system, but this has
been installed for the last 2-3 years now.

~~~
pfdietz
I wonder if air-to-air heat exchangers could address that cost issue.

~~~
wavepruner
Energy Recovery Ventilation (ERV)

[https://en.wikipedia.org/wiki/Energy_recovery_ventilation](https://en.wikipedia.org/wiki/Energy_recovery_ventilation)

~~~
pfdietz
Yes. I was wondering if the wheel-based ones had some means of killing
pathogens on the wheel, rather than transfering them back to the incoming air
stream.

------
scythe
One issue is that we seem to have an all-or-nothing view of infection. People
think that either a virus gets in your nose and you get sick, or it doesn't
and you're fine. This extends to thinking that either there is a risk or there
isn't, which motivates incorrect anti-mask arguments.

In reality, the _probability_ of infection varies continuously with the degree
of exposure, and the _minimal infective dose_ might be prevented even if not
all viral particles can be blocked.

[https://en.wikipedia.org/wiki/Minimal_infective_dose](https://en.wikipedia.org/wiki/Minimal_infective_dose)

With airborne transmission, it is practically impossible to reduce the
transmission probability to zero in many situations, and we have overlooked
the value of finite improvements. However, the circumstantial evidence
suggests that, since super-spreader events are correlated with apparently high
airborne concentrations of viral particles, that reducing the duration and
intensity of exposure may yield significant benefits even if inhaled air
cannot be made completely free of virions.

~~~
acqq
Exactly, that "all or nothing" is the main problem in in how most of the
people think about the whole topic.

I've read one work that gave the very simple estimates: if the infected person
wears the surgical mask it will emit 50% less in the air, and if the non-
infected person wears the surgical mask that person will get 60% of what's in
the air. But combined, that means that the non-infected person will get around
only 30% of what it would get when nobody would wear a mask. Which seems to be
way too little for personal "full" protection, but looking more globally:

If the R factor (reproduction number) is 2.7 with no measures, and if
everybody wears a mask and other limitations are respected (physical
distancing, limiting the number or people in the closed spaces, ventilation,
etc.), all together it can result in the R factor being reduced to less than
1: With the known no-measures factor 2.7 we have exponential growth. With the
factor under 1, we have a steady decay in the number of infected people.

There we also "just" have to reduce that factor to 30% of the no-measures one.
It's not so easy as some people spread to many, and a lot already don't pass
the virus to others. That's why groups of people near each other change
everything too much.

But just by maintaining the factor under 1 (the lower the better) we guarantee
that the relative number of infected around us will be always be smaller and
smaller, and that's can be more than enough for the population as the whole.

That's why wearing the masks and any additional good measures together do
help, even if every measure, evaluated alone, for only one person, "doesn't
protect" enough.

So it is not just either 0 or 100%, but everything in between: not everybody
has to use the same protection that the medical workers have to to improve the
chances for everybody. But everybody should do it. One person who's actually
infected and not wearing its mask changes the number of viruses passed to
anybody in its vicinity from 30% to 60%, when all the rest wear the masks, or
to 0 to somebody who's also not wearing the mask. From the starting 50% and
60% of masks "working" we get all the other outcomes too.

And the same is valid for testing. Rapid wide scale cheap testing to identify
who should enter the building doesn't have to be as good as PCR tests to still
give us immense benefits, if we have it and use it. We just have to be clear
that we want it, and that we know now it's not about "either 0 or 100%."

Also, the pictures (and the video) explaining much more than many words:

"Face coverings and mask to minimise droplet dispersion and aerosolisation: a
video case study"

[https://thorax.bmj.com/content/early/2020/07/24/thoraxjnl-20...](https://thorax.bmj.com/content/early/2020/07/24/thoraxjnl-2020-215748)

------
CogentHedgehog
Short-distance aerosol transmission changes things a bit:

* Social distancing isn't enough to guarantee safety in indoors spaces: bad news for bars, clubs, gyms, concerts, and restaurants

* Outdoors spaces are probably safer than we previously thought

* Indoor mask-wearing becomes CRITICAL in public spaces

* Indoor ventilation becomes extra important, using fresh air from outside or filtered/UV-sanitized air

* Indoor air purifiers with HEPA ratings or UV sterilizer features may become valuable

But the same overall guidance still applies: avoid crowds, wear a mask, keep
your distance, outdoors activities are safer than indoors activities

~~~
DanBC
> Indoor mask-wearing becomes CRITICAL in public spaces

Mask wearing provides minimal benefits against droplet transmission, but they
do nothing at all for small droplet aerosol transmission.

~~~
keenmaster
Studies have found that a combination of multi-layered cotton and chiffon/silk
masks prevents intake of both large and small droplets. Silk/chiffon act
magnetically on smaller particles to keep you from breathing them in, while
the thick cotton layers stop large droplets. The aggregate effect is similar
to N95, but more washable and reusable. It blows my mind that this was
discovered a couple months ago and the government still hasn’t funded the mass
production of such masks. After I read the study, I bought 2 masks on
Etsy.com: a multilayered cotton mask and a silk mask. I wear both when I go
out. What’s great is that I don’t just protect others from me, but I also
protect myself from others to a large extent (as opposed to just wearing the
cotton mask). As for comfort, silk is light and thin, so it doesn’t add any
noticeable discomfort on top of the cotton mask.

[https://news.uchicago.edu/story/homemade-masks-made-silk-
and...](https://news.uchicago.edu/story/homemade-masks-made-silk-and-cotton-
may-boost-protection)

Note: Newer studies have found that even just a thick cotton mask does
somewhat protect you (not as much as cotton + silk of course, but they protect
others from you quite effectively). You still need to be careful, generally
avoid indoor environments with strangers, and socially distance. Not that that
disclaimer is super necessary, because other studies have found that masks do
not make people behave more recklessly :) If anything, they make you more
careful and acutely aware of COVID risks.

~~~
DanBC
> Newer studies have found that even just a thick cotton mask does somewhat
> protect you

No they haven't. If the effect of masks was so strong it would be easy to find
that when we do trials. We've done the trials and we struggle to see the
effect. Once we drop down the quality requirements we start to see an effect,
but even that is mild.

[https://www.thelancet.com/action/showPdf?pii=S0140-6736%2820...](https://www.thelancet.com/action/showPdf?pii=S0140-6736%2820%2931142-9)

> Although direct evidence is limited, the optimum use of face masks, in
> particular N95 or similar respirators in health-care settings and
> 12–16-layer cotton or surgical masks in the community, could depend on
> contextual factors; action is needed at all levels to address the paucity of
> better evidence. Eye protection might provide additional benefits. Globally
> collaborative and well conducted studies, including randomised trials, of
> different personal protective strategies are needed regardless of the
> challenges, but this systematic appraisal of currently best available
> evidence could be considered to inform interim guidance

There's no way to spin phrases like "direct evidence is limited" and "paucity
of evidence" to mean "we've got good quality evidence that shows an effect".

------
DoofusOfDeath
The article makes an excellent argument for the _plausibility_ of indoor
airflows being a major transmission vector. But I didn't see anything about
ongoing research to quantify the transmission risks posed by aerosols vs.
other transmission mechanisms. (Maybe I missed it?)

It's hard to make policy recommendations regarding aerosols if (a) we're not
really sure how big a risk factor they pose _and_ (b) the mitigations would be
very expensive.

------
graeme
If anyone is in an indoor environment and wants to gauge risk, a portable co2
meter can be had for about $100-$150. Cod2 is a good proxy for indoor
pollutants/air exchange, and I’m assuming it is a good proxy for aerosols too.

I use one of these, you can use a portable battery to power it.

[https://www.amazon.com/AutoPilot-APCEMDL-Desktop-Data-
Storag...](https://www.amazon.com/AutoPilot-APCEMDL-Desktop-Data-
Storage/dp/B07JDJP4HH/ref=sr_1_15?dchild=1&keywords=Co2+meter+autopilot&qid=1596467296&sr=8-15)

~~~
newsbinator
Is there a reliable portable Co2/Pm2.5 logger?

I've heard the accuracy on the Pm2.5 ones at least is way off.

I just moved to a place where I need to keep an eye on Pm2.5 in particular.

~~~
graeme
It doesn’t log pm2.5. Only co2. For pm 2.5 I recommend a laseregg

------
unclesaamm
One key result of this evidence is that we should take all the money going
into deep cleaning, and spend it on higher quality masks for everyone. Also
perhaps makeshift ventilation systems (being careful not to replicate that
Hong Kong restaurant) or outdoor tents where feasible.

~~~
beamatronic
What was the restaurant doing wrong? Was it recirculating indoor air? Or was
it actually exchanging the air? Replacing indoor air with fresh air from
outside.

~~~
unclesaamm
The article links to the study. The issue was more than certain people sat
downwind of others indoors, rather than where the air came from. Let me know
if you read a different conclusion from it.

~~~
beamatronic
Now I’m really curious. How does one exchange indoor air safely?

------
kenjackson
There is a weird disconnect. Everyone seems to acknowledge the most likely way
to transmit COVID is via droplets when indoor. Yet, there is little discussion
about ventilation. Maybe people felt like there was less they could do?

~~~
ehnto
Gyms and restaurants have had their air conditioning off in Aus. Israel turned
off their bus air conditioning.

This isn't breaking news but I suspect it would be a new angle to the media
rhetoric for a few countries and media outlets.

------
ColanR
We probably aren't hearing about it because it's something we have less
ability to protect against.

I remember a popular comment here a while back mentioning that
epidemeologists' job is partly public relations, trying to figure out what
they can tell the general public that will minimize the viral spread.

Making sure everyone wears masks will, at the scale of the general population,
reduce the infection rate by some noticable percent. It's also something
everyone can do, and it gives everyone a sense of control over the situation -
enough of a sense, at least, to prevent chaos.

Talking about airborne transmission, though? The kind of masks that can
protect against that are hard to come by. Not to mention that the virus could
enter via the fluid of the eyes (not trying to add conspiracy here, just
trying to make a point about the difficult reality of preventing infection
[0]). Bio-rated goggles and N95+ rated masks are more than we can expect from
a public that's making face masks out of bandannas.

I think we're seeing very pragmatic statements being made, that are tailored
to a public that can't enter full biohazard mode and need to not panic.

[0]
[https://www.biorxiv.org/content/10.1101/2020.05.09.085613v2](https://www.biorxiv.org/content/10.1101/2020.05.09.085613v2)

~~~
sigstoat
> Talking about airborne transmission, though? The kind of masks that can
> protect against that are hard to come by. Not to mention that the virus
> could enter via the fluid of the eyes (not trying to add conspiracy here,
> just trying to make a point about the difficult reality of preventing
> infection [0]). Bio-rated goggles and N95+ rated masks are more than we can
> expect from a public that's making face masks out of bandannas.

plenty of evidence that even a little bit of protective gear helps. it isn't a
matter of hazmat-suit-or-GTFO.

~~~
ghaff
I think that's what the parent was saying. The widespread wearing of just
about any face covering seems to help on net even if it's probably >50% about
protecting other people. Even if higher-level protective gear were readily
available, most people wouldn't wear for any length of time and it wouldn't be
fitted properly. So just wear _something_ seems to be the most reasonable
advice for the general population.

~~~
misanthropian00
Do you have proof that people would not wear better protection and that it
would be ineffective even if they did to due fit issues? Or are you just
making an assumption?

The fact that N95 masks were and still are selling for such high prices seems
to be evidence against this view. I assume this view is most popular among
Americans because Americans seem to represent the majority of anti-maskers.

Where I live everyone wears a mask but very few people wear N95 masks simply
because they are more expensive and hard to find. If COVID is short range
aerosol infectious as some evidence suggests greater N95 mask availability and
usage may affect infection rates at least outside of the US. How significant a
difference this might make is simply unknown at this time.

------
tgb
One problem is that no one seems to know that AC systems recirculate air. I
literally can't get people to believe me when I tell them this. When buying a
window unit recently, some models had the ability to incorporate fresh outside
air but the cheaper ones didn't. My home is leaky enough that I worry more
about keeping outside air out rather than in, though.

~~~
sukilot
Do people not use the recirc switch in their car?

~~~
tgb
I think this actually makes it more understandable. If recirc is a special
mode you have to activate in your car's AC, then it's reasonable to assume
it's not the default mode for your house AC too. Since they never had a
'recirc' button to press at home, they'd assume it doesn't recirculate.
Reasonable, but inaccurate.

------
CogentHedgehog
There's one key paragraph buried in the article that will help a lot of
people:

> However, to date, there is also no evidence of truly long-range transmission
> of COVID-19, or any pattern of spread like that of measles. Screaming “it’s
> airborne!” can give the wrong impression to an already weary and panicked
> public, and that’s one reason that some public-health specialists have been
> understandably wary of the term, sometimes even if they agreed aerosol
> transmission was possible. Cowling told me that it’s better to call these
> “short-range aerosols,” as that communicates the nature of the threat more
> accurately: Most of these particles are concentrated around the infected
> person, but, under the right circumstances, they can accumulate and get
> around.

Translation: people _can_ get infected further away than with larger droplets
-- especially in stuffy, enclosed environments -- but distance still reduces
the risks.

~~~
DoingIsLearning
> people can get infected further away than with larger droplets

Minor nitpick, you can think of aerosol transmission as plume of virus
particles. Technically you can get infected long after the carrier has left a
closed room, at which point the concept of being "further away" stops
applying.

~~~
CogentHedgehog
That's true, in this case "further away" is a 4-dimensional distance vector
(it includes time). :D

------
js2
A couple other articles I've read in the last few days also cover this topic:

 _Yes, the Coronavirus Is in the Air_

> Transmission through aerosols matters — and probably a lot more than we’ve
> been able to prove yet.

...

> I am a civil and environmental engineer who studies how viruses and bacteria
> spread through the air — as well as one of the 239 scientists who signed an
> open letter in late June pressing the W.H.O. to consider the risk of
> airborne transmission more seriously.

[https://www.nytimes.com/2020/07/30/opinion/coronavirus-
aeros...](https://www.nytimes.com/2020/07/30/opinion/coronavirus-
aerosols.html)

 _Aboard the Diamond Princess, a Case Study in Aerosol Transmission_

> A computer model of the cruise-ship outbreak found that the virus spread
> most readily in microscopic droplets light enough to linger in the air.

[https://www.nytimes.com/2020/07/30/health/diamond-
princess-c...](https://www.nytimes.com/2020/07/30/health/diamond-princess-
coronavirus-aerosol.html)

And here's an article from two weeks ago that goes into some depth on
superspreading events:

[https://www.washingtonpost.com/health/2020/07/18/coronavirus...](https://www.washingtonpost.com/health/2020/07/18/coronavirus-
superspreading-events-drive-pandemic/)

> He believes ventilation may also be to blame for a case involving a young
> man from China’s Hunan province, who sat in the back of a bus but ended up
> infecting seven others in various areas of the vehicle and then two more on
> a second minibus he hopped onto next. Li interviewed the patient, driver,
> passengers and reviewed video footage and found it odd that few of those who
> became infected were nearby. In fact, at least one passenger who fell ill
> was as far away as possible at the front of the bus — 31 feet away — from
> the coronavirus-positive man. […] In the case of the Hunan man who
> transmitted the virus while riding two buses, Li said that “amazingly” after
> that four-hour window of infectivity, he is not known to have infected
> anyone else at all.

------
prof-dr-ir
I would like to make a small point about the letter signed by "hundreds of
scientists around the world".

According to the NY Times there were in fact 239 signatories, which
coincidentally is almost the same number as the "253 ... scientists from 44
nations" warning of the dangers of electromagnetic radiation (!) that can be
found at [https://emfscientist.org/](https://emfscientist.org/) . If you trust
one, do you trust the other also?

Regardless of the merits of the rest of the article, I would caution against
trusting a claim just because two hundred odd scientists from all sorts of
disciplines were willing to sign an open letter. Science is not a democracy.

~~~
briandear
The “appeal to authority” is also used to sell toothbrushes. I agree that it’s
foolish to trust an article or “fact” because 9 out of 10 doctors agree. I am
very interested in why that 10th doctor didn’t agree..

------
lurkmurk
The amount of unknown and disagreement after all this time and money spent is
a big failure of science. Laymen have a unique peak into how science works day
to day, which might be good or bad depending on how you see it.

------
misanthropian00
Yes it's a well written article by a clearly intelligent author who did his
homework and knows his sources and of course we should never have ruled out
short range aerosols. It's ridiculous. I think it only happened because so
many people just believe whatever authorities like the CDC and WHO tell them
without any critical reasoning applied. If these health agencies had not
effectively ruled out the possibility afaik without any supporting evidence
maybe there would have been more research to figure out droplet sizes and
travel paths under various airflow conditions. Currently everyone seems to
just want to make assumptions and stick to them, but that isn't science even
if you call yourself a scientist.

Maybe also N95 masks would have been considered essential not only just to
health care workers and maybe more effort might have been made to supply some
to the general population. Currently 3M for instance voluntarily stopped
selling their masks except to hospitals and speaking of those masks there is
also not enough research on effective ways of decontaminating those masks
without reducing their filtration effectiveness so that they can be reused
more often and so that more can be made available to the public instead of
effectively making them hospital only.

------
sigstoat
i wish target and home depot would stop making us wait in line while they futz
about wiping things down. it's been clear that time spent in line with other
people is a bigger concern than the possibility that something is lingering on
the barcode scanner and will be transferred onto my box of nails, or bananas.

------
cblconfederate
At the beginning of the epidemic, joe rogan hosted M.Osterholm for an
interview where he warned about a lot of the things to come: the rapid spread,
the small effect of washing hands or masks, the airborne spread etc. It's sad
that the epidemic seems to have turned worse than most ppl assume it would.

------
ianpenney
[https://www3.nhk.or.jp/nhkworld/en/news/ataglance/855/](https://www3.nhk.or.jp/nhkworld/en/news/ataglance/855/)

From April, Japan has been on top of this for a little while. Impressive
science imho.

~~~
sukilot
And yet Japanese government _declared_ victory and campaigned against
protective measures leading to a massive re-ourbreak, "for the economy"

~~~
thiagocesar
Japan has some really impressive universities and, as a rich country, is able
to nurture all sorts of talent.

The Japanese ruling party is a bunch of old people from a few traditional
families mixed with some new faces.

It’s very unfortunate how little these two worlds (talented people and
politicians) collide.

------
KoftaBob
This comes to mind every time I see a company/business emphasize how much
priority they're putting on keeping people safe, and then only speaking about
disinfecting every surface throughout the day.

While it doesn't hurt to keep surfaces clean, we continue to see evidence that
the majority of cases have come from airborne spread in an enclosed
environment with poor ventilation.

If there's any lasting change to building environments that comes out of this,
I think it should be an overhaul of building ventilation codes to
require/heavily incentivize systems that replace air rather than circulate it.

~~~
lostapathy
Because wiping high-contact surfaces a few times a day is cheap, easy to do,
and highly visible. And, hopefully, an easy extension of nightly cleaning that
was already happening.

Reworking your HVAC system to provide better circulation, filtration, and/or
more fresh air is expensive, often an ongoing cost, and probably invisible to
the end customer.

I guess you could say it's well-intentioned virtue signaling.

------
thinkingemote
in the UK the LNER train company highlights ventilation amongst other things,
but the ventilation bit I found suprising when I encountered it.

[https://www.lner.co.uk/travel-information/lets-travel-
togeth...](https://www.lner.co.uk/travel-information/lets-travel-together-
safely/)

" Our onboard ventilation systems are providing a continuing supply of fresh
air which is cycled every 6 minutes limiting droplet transmission between
passengers." With the graphics implying that ventilation is spatially limited.

~~~
tialaramex
The closest to air-conditioning possible in trains like LNER's is more similar
to individual window units (except mounted in the ceiling) than the integrated
systems in larger homes or offices.

LNER operates two types of multiple-unit from the same family (a conventional
EMU and then a bi-modal hack of that concept because the Tories don't want to
spend money electrifying more of the railway), and then an older loco-hauled
passenger service where a type 91 is pulling and there's a train of mostly
passive passenger stock behind it.

In both these designs there is electricity available, to run the air
conditioning units, but it's not practical to pump air around the train so
they don't. The air in your part of the train will get recirculated by the
fans that make the air conditioning unit work, so I'd expect that if you spent
an hour on a train four seats from an infectious person there's a decent
chance you'll be infected. But air from other carriages isn't recirculated
into yours at more than negligible level.

Because these are mostly doing intercity journeys (thus fewer stops, and
perhaps dwelling for longer at each) even the newer EMUs were not designed as
a single huge tube like the modern Tube stuck or some local EMUs. So there's a
"double airlock" partition between one carriage and the next which reduces
noise and discomfort but makes getting on and off take a little longer. In
this particular case it probably makes the train slightly safer to use.

------
mensetmanusman
I am sympathetic to what the WHO did here, they realize that the average
person is going to be extremely fearful when they realize that stagnant air
could contain virion particles hours after being sneezed in (which is what the
data show).

They should have erred on telling people, because then we would have had
months to ramp up room air purifiers before school starts... (I have been
saying this for months, and am surprised by the lack of scientific leadership
in ‘science’ organizations).

~~~
klysm
Why should the WHO not incite fear if the fear is entirely rational and
justified? People not being afraid enough is exactly how people die.

------
nabla9
Just look at the list of people who signed the letter.

They are experts in their field but they don't have the expertise to consider
the whole picture.

It's possible, that there is some airborne transmission besides droplets, but
there is no evidence that it's significant transmission route. To get infected
you need big enough dose of virus at once. Just some dry floating particles in
the air is not enough.

------
jsonbourne
There is this startup which came up with the solution for the airborne
problem.

[https://yourstory.com/2020/07/startup-bharat-kanpur-
crestkit...](https://yourstory.com/2020/07/startup-bharat-kanpur-crestkiting-
retail-air-purification)

------
rurban
There are no receptors in the mouth, only nose and eyes. So the mouth does not
need to be protected passively, the only problem is that the mouth is the only
actor to spread the virus effectively.

------
whydoyoucare
I think we can't talk about it because there is no agreement on terms, modes
of transmission, etc. and public policy cannot be based on ambiguous terms
(though it can be based on imperfect data).

------
eqdw
Talking about airborne transmission would make it too obvious that masks are
pointless security theatre. Can't have that

