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Comment by jennyyang | Hacker News Reader

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.

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> If someone with coronavirus sneezes in a room, the large heavy droplets will quickly fall to the ground.

This is the slightly incorrect part with COVID.

Traditionally, this would be an appropriate description for other droplet transmission (like the flu). However, it seems COVID has an above average ability to survive in extremely fine droplets - think mist-sized particles that CAN float in the air for an extended period of time (given the right circumstances).

This nuance is challenging to convey. For healthcare workers, it's important because it likely means standard droplet based precautions are not enough. However, it also seems that full airborne precautions (PAPR's) are overkill. My take is N95's do enough to dehumidify droplets and ultimately break down particles.

For the general public, the nuance is less important. Most don't have access to proper fitting N95 (or better) masks, so they're stuck wearing cloth or surgical masks. They should simply think of COVID as airborne because they're likely not wearing the proper gear.

I don't see what was incorrect about the parent.

It goes on to say "However, there are microdroplets which stay in the air for 30+ minutes depending on the air currents."

It sounds like you're both in agreement that large droplets fall quickly to the ground, and that with COIVD the longer-lasting micro-droplets are a relevant factor.

Am I missing a subtlety?

There are no "microdroplets" which stay in the air for "30+" minutes.

First, water DRIES OUT unless the humidity is very close to 100% which is relatively rare in western countries. The smaller droplet the faster this happens.

Put a very, very small droplet on a flat surface like glass. Observe it disappear within couple of minutes. Then imagine that a smaller droplet is just larger droplet closer to drying out.

Volume increases with cube while surface with square of diameter. When the droplet gets smaller the drying out speeds up.

The only time there are persistent droplets of water in air is called fog and happens when air is supersaturated with water. This happens when you cool air that is already 100% humidity. In that circumstance water cannot evaporate and that is what makes it possible to have water droplets in air. Once the relative humidity falls below 100% even a tiny bit, the fog almost instantly disappears.

Ability of virus to be airborne means it can survive outside droplet of bodily fluid for an extended period of time. Once all water dries out it also becomes very light and can be moved by smallest currents of air.

I appreciate the distinction you're making here. I don't have enough facts to prove or disprove it.

But, I'd like to ask: are you suggesting that aerosolized droplets cannot be seriously spreading this disease because they will evaporate almost instantly?

I ask because there is quite a bit of research suggesting that aerosolized droplets are spreading the disease, and can hang int the air for a substantial period of time. Do you think this is wrong? If it is wrong, why do you believe people are suggesting aerosolized transmission?

Well... I am not suggesting anything.

There are two types of viruses: airborne and not airborne. Airborne can survive for some time outside bodily fluids.

Aerosol == bodily fluid that is still liquid. It is just in the form of very small droplets that are now drying out. Depending on conditions this lasts very shortly. It spreads the virus, of course, but aerosol dries out quickly and viruses that are not airborne die (well.. viruses do not live in the usual sense, basically their proteins get damaged).

Of course if somebody coughs in your direction some of the aerosol can be inhaled or reach your retina or get on your hands and you can get infected.

No, I am not suggesting droplets cannot spread the disease, the opposite is true. Droplets are much better transmitter of disease if they can reach the target.

I suggest you educate yourself on the topic of microdroplets.

https://www.weforum.org/agenda/2020/04/coronavirus-microdrop...

I suggest you educate yourself.

https://en.wikipedia.org/wiki/Airborne_disease

"Airborne transmission is distinct from transmission by respiratory droplets. Respiratory droplets are large enough to fall to the ground rapidly after being produced (usually greater than 5 μm), as opposed to the smaller particles that carry airborne pathogens. Also, while respiratory droplets consist mostly of water, AIRBORNE PARTICLES ARE RELATIVELY DRY, which damages many pathogens so that their ability to transmit infection is lessened or eliminated."

Here, I capitalized it for you so you don't miss it.

Airborne virus is what happens after fine respiratory mist dries out, which happens quite quickly. It is "relatively" dry because some of the respiratory fluid is hygroscopic. Don't make a mistake, there is no free flowing liquid with virus happily swimming in it.

These threads are awful because "droplet" and "aerosol" don't have good fixed definitions, and because people misuse the word "airborne" to mean "aerosol".

Yes, there is a lot of education problem when you want to discuss anything virus related.

Aerosol == small droplets of water.

Airborne, particles == no droplet, just leftover of an aerosol that dried out in less than 100% humid air.

It would not be the first time that health-related article on an economic website gets physics wrong.

Thank you, you're repeating things I've already stated in my first post. I suggest reading things more carefully.

In your refusal to read the article, you're missing how sars-cov-2 is teaching us new science about how viruses may survive in aerosols, which behave differently from particles that travel in a ballistic motion.

Airborne viruses have been known for a long, long time. The physics is established. The whole reason we distinguish between airborne and non-airborne viruses is exactly because virus needs special arrangements to be able to survive outside of fluid.

While it is interesting how particles move in a room, it is completely different topic. The particles ARE NOT AEROSOL. The kind of aerosol that can flow in tiny air currents dries out in seconds and becomes small particles (not droplets) of "relatively dry" matter that is fine enough to stay in air for a very long time.

True. And I am curious whether things can be done in most building's HVAC systems to account for this.

The ideal would be:

- Heavy external air exchange OR heavy filtering (think N95-level filtration on the return air exchange

- Diffusers are at foot level (not common)

- Return air in ceiling

- People wear masks

My fear of school spread is that folks are basing their mental models on the flu, and if this hangs in the air for an appreciable amount of time then classrooms are difficult to keep sanitized.

Good luck out there. Thanks for the knowledgeable comment.

"However, it seems COVID has an above average ability to survive in extremely fine droplets - think mist-sized particles that CAN float in the air for an extended period of time (given the right circumstances)."

This is one of those "facts" that is often repeated, but which has little actual evidence if you bother to look for it. The WHO has been consistent that aerosol transmission of the virus is a theory with little backing evidence:

Some outbreak reports related to indoor crowded spaces have suggested the possibility of aerosol transmission, combined with droplet transmission, for example, during choir practice, in restaurants, or in fitness classes. In these events, short-range aerosol transmission, particularly in specific indoor locations, such as crowded and inadequately ventilated spaces over a prolonged period of time with infected persons cannot be ruled out. However, the detailed investigations of these clusters suggest that droplet and [transmission from contaminated surfaces or objects] could also explain human-to-human transmission within these clusters."

"Current evidence suggests that SARS-CoV-2 is primarily transmitted between people via respiratory droplets and contact routes – although aerosolization in medical settings where aerosol generating procedures are used is also another possible mode of transmission"

https://www.who.int/news-room/commentaries/detail/transmissi...

ARS did a pretty good job of summarizing the (IMO terrible) mass-media reporting on this issue:

https://arstechnica.com/science/2020/07/no-the-who-has-not-r...

> although aerosolization in medical settings where aerosol generating procedures are used is also another possible mode of transmission

I'm married to a physician and have been primarily following this through the eyes of her and her peers. In an acute care setting, aerosolization is a huge concern. It's a big factor between being able to get away with a surgical mask/face shield and requiring significant PPE.

In daily life, this probably isn't a huge concern (or a significant means of transmission at a public health level).

Sure, absolutely. If you're in the business of intubating people on a daily basis, then it's a real concern.

This is what the article challenges.

The author provides cases of events where infection by droplets cannot entirely explain the spread.

> 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.

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.

Um.. it is airborne, that is why there are multiple super-spreader events that can’t be explained by someone interacting within 3-6 feet for 10 minutes. (e.g. cases of 1 to 100, 1:500 case reported as well).

If you walked into an empty hospital room that was just used with high air-virion density, you could get infected, that is why they decontaminate with the equipment you see.

I think the main reason this isn’t being communicated is because we will never have enough N95 masks to mitigate this (would need 5-10 years of 24/6 production to fill govt. stockpiles).

I would bet that you are right, but it is still a controversial opinion, and droplet transmission is probably still a major factor. Plenty of research supports the claim, although some studies conclude that it is only significant when the spreader has a high viral load:

https://www.nature.com/articles/s41598-020-69286-3

https://jamanetwork.com/journals/jamanetworkopen/fullarticle...

https://www.medrxiv.org/content/10.1101/2020.07.16.20155572v...

https://www.medrxiv.org/content/10.1101/2020.07.13.20153049v...

Ok - these multiple superspreader events... do you mean 100's or 10's or a few? And when you say "can't be explained " really? Can you provide some back up to this information?

https://jamanetwork.com/journals/jamanetworkopen/fullarticle...

https://www.vox.com/21296067/coronavirus-covid-symptoms-supe...

(put the air purifiers in the bathroom it seems...)

>Even stores like Costco and all factories would have to shut down.

That would kill a lot of people too. It's not obvious to me which would be worse, particularly in the face of such a low IFR.

thanks for continuing to tease out the nuance. nearly all coverage and discussion of covid is an exercise in frustration, one way or the other.

the unrealistic desire for riskless, surefire mitigations had led us exactly into the ping-ponging uncertainty that such longing tries so strenuously to avoid. it's wreaking havoc on our social and economic lives, let alone politically.

taking into account what we know so far, the best bang-for-buck rule is still "distance (inside), and when you can't, mask.", not shutdown, or mask outside and all the time, or never mask or distance, or business as usual, or wipe down surfaces incessantly, or reconfigure every hvac system.

the simplicity of that one rule belies a lot of understanding packed into it, unfortunately, leading to an unnecessary yearning for more. there isn't more that we ordinary folks can do than that. that's not to say don't be cognizant of the progress we're making, but does suggest we need to stop fretting while we wait for more effective treatments, herd immunity, and/or a vaccine.

> 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?

You don't seem to be engaging with the "airborne on droplets" vs "airborne aerosol" vs "airborne on dust" discussion that spawned this subthread.

Yes you are misunderstanding me.

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.

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"

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.

That's where the six feet distance part comes in.

WTF is going on here?

You claim "If the virus were truly airborne, which it isn't" yet provide no evidence.

But looking at you history you have provided exactly evidence that it is airborne "Video showing microdroplets suspending in air (vimeo.com)" a few months ago (https://news.ycombinator.com/item?id=22776194)

And to quote from another commenter "The part showing how a single cough can create a room-wide cloud of virus that lingers for 20+ minutes in spaces with poor circulation was especially enlightening."

Having watched the vid I can confirm that's what they show, at least as a simulation.

Even the main article says (I'm re-quoting from another of my posts): "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" which directly opposes what you say.

How is your parent post not either plain wrong or deliberately sowing confusion? I'm flagging you.

> Edit: To those downvoting, I'll just say that my statement is factual, so argue the facts.

I wonder if the downvotes were caused by the phrasing of this statement:

> Most people and countries don't have this goal.

At first I thought you were saying that people didn't actually want to stop the virus in its tracks.

It took me a minute to realize that you're saying people have accepted full-stoppage-in-tracks as being infeasible, and therefore don't consider it an attainable goal.

> At first I thought you were saying that people didn't actually want to stop the virus in its tracks.

No, I think that's precisely what they were saying. I don't think that this is unattainable - I think it would have a greater economic cost, particularly to the wealthy, than many countries are willing to bear. It's not unattainable - it would cost them more than those lives are perceived as being worth. Big conceptual difference.

It's not only economic cost. To get results like in china you have to be (like) china. It's easy to sell drastic measures to the population if the infection (and death) numbers look scary. But if the numbers stagnate at low values nobody is going to accept drastic measures. You would need to fight against your own population to stop the virus altogether. And even if you achive this, the virus will return (tourist/travelers).

> I'll just say that my statement is factual

> assume

> goal

An assumption is not a fact. A goal isn't a fact either.

While total elimination is probably impossible, plenty of places have managed almost complete suppression to the point where it's more like E. Coli; occasional outbreaks, but action taken to contain it.

"flatten the curve" is now associated with "herd immunity" and other discredited ideas.

I think you may have responded a little hastily and misunderstood the comment.

---

> An assumption is not a fact.

Correct, and the person you were replying to never implied that it was. I'll rewrite the comment more explicitly for you, instead of using the implied context of the quotation:

> If the goal was not to flatten the curve but to completely stop the virus in its tracks, we would have to implement extremely strict lockdowns. Most people and countries don't have this goal [to completely stop the virus]

---

> A goal isn't a fact either

"Entity X has goal Y" is, indeed, a fact. (EDIT: Or, rather, a statement - which may or not be factual) The person you were replying to claims "Most people and countries do not have the goal to completely stop the virus" as a fact. Neither you, nor they, have provided evidence for or against the factuality of this statement.

---

Can you elaborate on what, exactly, is discredited about "flattening the curve" - shorthand for "reducing the rate-of-increase of new cases, so that the throughput of new cases is within the carrying capacity of the country-in-question's medical infrastructure"?

Almost all countries are pursuing a herd immunity strategy by default, just at varying rates. Only a handful of countries are actually taking steps to eradicate the virus within their borders.

The whole "flatten the curve" messaging always seemed like we were barreling toward a misunderstanding, and I think this comment and the disagreeing downvotes are a perfect example of that.

Back when US public health messaging really went all-in on that phrase it was like late February when we thought the transmission level was minimal. "Flattening" the curve at a minimal level would have been fine, and if we got the reproduction rate even just barely below 1 the infection would have died out.

Flattening the curve when there are 10,000 people dying a week is a very different situation, and I don't think ending up there was ever explicitly anyone's goal (except for famously Sweden). But that's what we finally ended up achieving in April, and everyone basically patted themselves on the back for it and started treating the pandemic as over. It should have been very clear to anybody paying even a little bit of attention that once we started approaching and then surpassed "running out of ICU beds"-level of crisis in some places, that flattening the curve anywhere near that level would not be good, and when we did start to plateau at only like 30% down from the peaks we were nowhere near in the clear. But for whatever reason we just ignored that inconvenient fact and acted as if our lockdown had worked. After all, we had "flattened the curve".

Obviously the world is quite complicated and this is impossible to predict, but I genuinely wonder what would have happened if a more ambitious catchphrase had caught on instead like "zero out the curve". It's well-known that laypersons are naturally bad at reasoning about exponential growth, but I also think the public health "experts" really let us down as well in their failure to properly account for the exponential growth as well.

Flattening the curve was about preventing the hospital system from being overwhelmed. It was about solving the crisis from the point of view of civic administrators and politicians. So, keeping people safe was a secondary goal: the primary purpose was to keep the system from failing outright.

IMHO, consequent to the misinterpretation of this, people assumed that if the curve was flattening, the problem was being solved, since they thought that the curve was about their safety, rather than about stretching the deaths out so that queues didn't form.

More important would be fixing the messaging on masks and protection. (Most laymen aren't going to distinguish between droplet, aerosol, airborne, etc. and won't adjust behavior and risk profiles accordingly.)

The CDC told people that masks were not important at the start of the pandemic, largely as a means of reserving stock for doctors and first responders. They then performed an uneven and awkwardly stilted 180 on that message. This massively backfired and led to wide scale public distrust of the public health apparatus. The birth of the anti-mask movement, etc.

We'll be living with the ramifications for a long time.

You shouldn't lie to the public.

> The birth of the anti-mask movement, etc.

Hogwash. Those people would have latched onto something else. The 1918 pandemic also had its "anti-mask" idiots.

Stupid is timeless and universal.

> You shouldn't lie to the public.

Agreed. Calling an active pandemic a "liberal hoax" started a huge problem.

You are being unfairly downvoted.

You are right in that the anti-mask movement did not start because the CDC reversed its position. (Thank you for citing 1918 as a supporting point.) The anti-mask movement started because everything in American politics has to be turned into a right-left culture war, regardless of whether the issue is actually controversial, or if it has a simple, obvious solution.

The people leading the Covid denialist movement aren't stupid. They are just cynically scoring political points with their base.

This is a bit of an outdated view on Coronavirus though. The whole point is that “airborne” isn’t black and white (which is how the WHO has treated it) and is more of a spectrum. A large number of scientists have been lobbying the WHO to get them to talk about it as airborne because it’s not just heavy droplets like people thought in the beginning. And there’s real concern that viral load can build up in poorly ventilated spaces. Which is why it’s a good idea to spend as little time in closed public spaces as possible, and why Fauci suggests that if you’re someone who needs to avoid it at all costs, then goggles are probably a good idea.

I don't agree with your conclusion. Airborne is airborne regardless of whether it's 5 minutes or 12 hours. The point of the word is to tell people that you can become infected without being in direct physical contact with them. Trying to come up with words for different durations of airborne is only going to make it more confusing, even if it becomes less ambiguous to the people who know the difference between the terms.

I disagree. You need to treat the virus at the right level of concern otherwise you lose credibility. As we can all see, credibility from the experts needs to be maintained, otherwise no one trusts them anyone. The whole fiasco with masks is because the experts told us things that were obviously wrong at the beginning (ie. masks don't work, masks won't help regular people, etc).

If there is airborne droplet transmission, which I believe is the case otherwise we wouldn't get such infectious spread in bars, etc, then we need to implement better ventilation, social distancing and mask wearing and probably goggles too.

If it was truly "airborne", which it isn't, then the measures would need to be much, much more draconian otherwise it would spread much quicker.

> If it was truly "airborne", which it isn't, then the measures would need to be much, much more draconian otherwise it would spread much quicker.

You need to make up your mind here, are you talking to professionals, or lay people?

To lay people the term airborne means it spreads by air... which is what it does. The fact that it doesn't linger in the air for 12 hours is secondary and would need to be addressed in whatever policy is put in place.

Since we don't need lay-people to understand what the virus isn't, the term airborne is just fine.

> You need to treat the virus at the right level of concern otherwise you lose credibility.

I agree with this but don't see how the use of the word "airborne" conveys concern. Maybe this is some american hollywood trope now that I remember reading the phrase "It's airborne!" in the original article? Wikipedia's article on airborne diseases certainly don't seem to imply that there's a strict definition of how long a pathogen has to survive in the air for it to be classified as airborne.

> As we can all see, credibility from the experts needs to be maintained, otherwise no one trusts them anyone.

While I agree with this, we're in an age of misinformation and macho power culture where saying "we're not sure yet so let's just be as careful as possible" apparently doesn't do much good in many places of the world. And I don't think a technically incorrect use of a word like airborne is NEARLY as significant as changing stances on masks and presidents endorsing quacks.

It's possible, if annoying, to simply wait 5 minutes between trips while the elevator car's air clears. It has to be handled differently (eg using a fan) if it would take 12 hours for the air to clear.

Given that we are all talking about COVID-19, as caused by the SARS-Cov-2 virus, (and not any other disease), the exact word or phrase used in popular media is less important, what's important is for people to recognize that breathing someone's are 5 minutes later is hazardous. Would you even know if there was person in the same elevator car as you 5 minutes before you came along? How can you recognize if they were actively symptomatic and positive and not wearing a mask. What it's called by scientists is less important compared to outright science denial going on.

Even before "global warming" was renamed "global climate change", people are able to learn and understand the phenomena that it refers to, even if there are idiots that say "global warming isn't real" because they felt cold at some point. With today's instant access to information, I want to push back against the idea that everybody who cares to ask is too dumb to learn the difference between "airborne" (12 hours) vs "airborne droplets" (5 minutes).

This is why science communicators are extremely important. Technical words are great for trained professionals who understand the context. But too many people, myself included, repeat these words only partially understanding what they're intended to mean.

All of the media messaging around COVID has been a complete disaster from the moment it became apparent it was spreading in January in China. One of the main takeaways from this pandemic needs to be that doctors and experts need to learn how to say the words: "I don't know, but we are working hard to find out." Way too many people have made statements that later turned out to be false. The lack of any consistency and the complete flip-flopping on masks has completely undermined the public's willingness to trust the experts.

The messaging regarding masks was "They don't keep you from getting it, and everyone should be inside right now to avoid spreading it if they have it, so avoid buying a mask to make sure there are enough for people who need them." The messaging regarding masks now is, "They don't keep you from getting it, but they do stop you from spreading it, so since there are enough masks now for everyone, you should wear one." It doesn't seem like a flip-flop so much as responding to the current state of the world.

I think the public's willingness to trust the experts has been undermined more by a large portion of the US government deliberately trying to undermine public trust in the experts.

“When to use mask:

- If you are healthy, you only need to wear a mask if you are taking care of a person with suspected #coronavirus infection.

- Wear a mask if you are coughing or sneezing”

WHO, Mar 1, https://twitter.com/who/status/1234095938555260929?s=21

“the wide use of masks by healthy people in the community setting is not supported by current evidence and carries uncertainties and critical risks.”

WHO, Apr 6, https://apps.who.int/iris/handle/10665/331693

That second source goes on to point out that its major concern (in terms of "uncertainties and critical risks") is healthy people using medical masks in places where there isn't enough supply and depriving healthcare workers of them, like I said. It specifically does not advise against nonmedical masks, and simply notes that the WHO was still actively studying their use at the time and would make a recommendation when evidence was available.

So the "flip-flop" here was the WHO saying "I don't know, I'm looking into it," and then later saying "I've looked into it and have some strong recommendations."

My friend uses "aerosols" for the latter term

And we have studies[1] that show UV light kills the virus in less than a minute which further limits airborne spread outdoors during the day[2].

[1] https://www.cuimc.columbia.edu/news/far-uvc-light-safely-kil...

[2] Even on overcast days, as people who forgot sunscreen on cloudy days can attest too.

The article addresses this midway through. The problem is that even the experts haven't really agreed on terminology. They need to do that first before they can hope to inform the public. :)

So why talk about HVAC systems ?

Context:

>” by 10 bottles of hand sanitizer without a word on ventilation—whether it was opening windows, employing upgraded filters in its HVAC systems, or using portable HEPA filters. It seems baffling that despite mounting evidence of its importance, we are stuck practicing hygiene theater...”

Sorry, what do you mean?

I suspect the parent post meant "why not", as in "improving HVAC would be more effective than the omnipresent hand sanitizer, so why aren't we talking about that?"

One important point that comes out of this is that few people are stressing shoe sole hygiene. Not necessarily meaning that one has to scrub them often, but to be mindful of what it touches (car interior mats, mats at home and possibly if people don’t take off their shoes, all over the house, hands taking off shoes, shoe racks, etc.) Given that droplets mean the virus will accumulate on floors and such surfaces.

why would that matter? transmission from surfaces is apparently quite low, and it doesnt last long on surfaces, and its not like im touching / eating off anything my shoes come into contact with anyway. This feels like an incredibly low risk vector

Low but greater than the “aerosolized” vector. When people sneeze, it land on surfaces (like floors), when they cough, etc.

If surfaces were not a problem, we wouldn’t be using wipes and sanitizers. So why ignore one possibility and stress another?

When people take off their shoes they can get contaminated. If they have pets the pets will pick some up and get it on you, etc.

The incessant use of wipes and sanitizers is basically "Hygiene Theatre" [1].

> In May, the Centers for Disease Control and Prevention updated its guidelines to clarify that while COVID-19 spreads easily among speakers and sneezers in close encounters, touching a surface “isn’t thought to be the main way the virus spreads.” Other scientists have reached a more forceful conclusion. “Surface transmission of COVID-19 is not justified at all by the science,” Emanuel Goldman, a microbiology professor at Rutgers New Jersey Medical School, told me.

[1] https://www.theatlantic.com/ideas/archive/2020/07/scourge-hy...

A place to put outside shoes and put on inside slippers (flip flops in my case) is good for clean floors anyway. I highly recommend, whether that’s a little mudroom or just a walled rubber/plastic container to take off shoes.

That said, I’m not sure it does much for this particular virus, but it can’t hurt and your floors (especially carpets, but those are nasty anyway) stay much cleaner.

The solution here : don't lick the floor.

Understood but think pets and of children who could later carry it to you.

I don't want to minimize Covid - of course you must protect yourself as you see fit.

Is a better distinction Dry Airborne vs Wet Airborne? There is still particle size to consider I guess.

I propose calling airborne droplets “germ infested mouth farts”. It’d definitely get the 4 year olds on board.

that's pretty disgusting and vulgar. I'm down!! :)

That's pretty disgusting and vulgar. Let's not.

> If coronavirus were truly airborne, then we would all need to wear masks all the time, even when no one is around.

Cloth masks wouldn’t protect against that. Masks don’t do anything to stop airborne spread, only potentially mitigating droplet spread.

Unless you are referring to biohazard respirators as “masks.”

The WHOLE POINT of the article is to educate you about the difference between droplets (ballistic) and aerosols (behave like a gas).

It doesn't look like you, or the people replying to you read the article. And thats a shame, because you're exactly the type of person who the author is trying to educate.

Please read and follow the site guidelines. You broke several of them here, and have been doing so elsewhere also.

https://news.ycombinator.com/newsguidelines.html

I believe that’s why the parent comment said scientists and medical experts should improve how they explain terms going forward. People like OP should not be this confused about how the virus spreads after 4 months of hearing about it all the time. I’m glad we have magazines helping fix that problem now, but communication from places like the CDC hasn’t been totally understandable to normal people. (Add a healthy dose of misinformation and propaganda and you get today’s situation :))

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