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DoomGoober t1_irkcyd6 wrote

A study estimates that touching a contaminated surface would lead to infection with SARS-CoV-2 only 1 in 10,000 touches.

https://www.cdc.gov/coronavirus/2019-ncov/more/science-and-research/surface-transmission.html

Then you have to take into account how long a surface remains contaminated or what it takes to contaiminate a surface.

Overall the risk is considered low and the main transmission pathway is considered respiratory droplets.

There's a "funny" story about why public health initially assumed SARS-CoV-2 was not spread via respiratory droplets: they accidentally used the number 5 microns as being the max size of water droplets that behaves airborne. The real number is closer to 100 microns. Once public health realized they were drastically overestimating which droplets will fall out of the air rapidly, they realized that the airborne respiratory droplets made a lot more sense and jibed better with what the case studies and experiments were showing about SARS-CoV-2 transmission. This same mistake plagued flu research as well and it explains why fomites were a mistaken emphasis around both flu and Covid prevention.

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carrotwax t1_irlldsm wrote

Thank you - I wish public health officials and media had publicly educated people more of the low (but not zero) risk of fomite transmission. There are still people terrified getting Covid this way and there still exists cleaning regulations that were created at the beginning of Covid for extra cleaning. One may think the extra cleaning does no harm, but IMO that's a privilege - requiring low wage workers to do medically unnecessary cleaning many times a day above what was there before is kind of soul sucking, especially if that work is already on top of existing job requirements.

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eddiepaperhands t1_irlrokj wrote

Yes, and any useless precautions we ask people to take reduce their ability and willingness to do things that do matter, like improving ventilation in buildings.

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ackillesBAC t1_irmza33 wrote

The extra cleaning with in appropriate cleaning products also causes issues with electronic and mechanical repairs.

I'm a tech and our service calls massively increased for bank machines due to buttons and mechanical items sticking. Also touch screens failing due to a layer of cleaning residue.

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eddiepaperhands t1_irlrlts wrote

This is all correct, except the experts were extremely reluctant and slow to accept that they were wrong about aerosol droplet size.

But yeah, it seems respiratory illnesses are mostly spread by aerosol particles, and washing your hands mostly matters for things like norovirus.

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GuyWithLag t1_irm805h wrote

>This is all correct, except the experts were extremely reluctant and slow to accept that they were wrong about aerosol droplet size.

This is an adaptation to science and public health reporting. The general public has been trained to not understand the scientific process, and "hey folks, we were wrong in our research and now you need to do X and stop doing Y" makes Joe "Moron" Public go "Hah, see? Science can be wrong, what else have they gotten wrong too?".

This isn't helped by there being monied interests in play.

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eddiepaperhands t1_irmx0zk wrote

Lying by doubling down doesn’t help their credibility. Sometimes you just have to take the “we were wrong” medicine and let morons be morons.

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eddiepaperhands t1_irmx6gw wrote

How many people died because their pride wouldn’t let them admit they were wrong and issue corrected guidance regarding ventilation in buildings? My guess is thousands.

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taleden t1_irn02jk wrote

It's not just pride, though, it's an actual public health cost/benefit calculation.

Yes, admitting the mistake promptly would have saved some lives through improved prevention behavior among the people who cared to try to follow prevention guidelines.

But it would also have caused other people to be even more distrusting of public health guidance in general, both as a genuine reaction among that population and also because it would invite certain sociopolitical forces to pounce on the opportunity to scream "see?!? they were wrong this one time!! never listen to them again, only ever listen to me, yaaah tyranny blah blah!!"

So do you focus on saving more lives in the short term for this one situation, or do you focus on not accidentally reducing public trust in science in general so that you can save more lives next time, and the time after that, and so on? It's not such a clear choice.

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The_Middler_is_Here t1_irne7du wrote

Sorry, are you actually suggesting that lying to the public is the better long-term option?

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Ravatu t1_irnmpve wrote

I believe OC is saying it's not a clear choice.

It seems to me like you're making a great example of the issue OC refers to.

The decision is between accepting study A (small particle assumption) and study B (larger particle assumption).

In the environment where this decision is being made, CDC is giving direction to both clean surfaces and mask up. Their priority is public health. If study A is correct, and they back it, they continue to protect against both potential pathways. If study A is correct and they back study B, they are giving people direction to stop cleaning surfaces - people will stop cleaning, and then die.

They stuck with the most risk-adverse option while the assumptions around particle size developed.

Also, it's worth noting this: scientists that study Stokes law (the physics behind where a particle will float or sink, and how long it will take to do so) aren't necessarily experts at HVAC design. Stokes law is a force balance between drag force and particle weight. Drag force is different outside, vs. inside, from home to home, even floor to floor. It can flip if you're heating a building versus cooling a building, and even flip in the atmosphere (look up atmosphere inversion).

It is a complex issue. It's not just a bunch of particle scientists realizing that they were wrong about one equation (Stokes law) in a eureka moment. It's a group of different fields coming together to refine assumptions about what the average drag force is in a social setting. No model is perfect. If science and engineering waited for models to be perfect before applying data to real world, every industry would just stop.

Yet, some of us look at the issue as black/white. "Scientists were lying to us!" "The government knew the whole time and CHOSE not to tell us!" Even in the r/science community, we can all have emotional responses to data.

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formgry t1_irnixbb wrote

Long term the best way to keep people following covid prevention methods is achieved by not changing up the narrative too much. Your narrative may be more accurate if it changes all the time, but it will be completely ineffective at getting people to follow practical prevention methods.

That is what he's saying.

Call it lying by omission if you want to be abrasive.

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GuyWithLag t1_irmzxby wrote

It's not a matter of pride, you fool. Did you even read what I wrote? It's not scientists that drive this, it's a political topic, the MAGA morons made sure of that _exactly because it's a divisive topic_.

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Canazza t1_irm5ciw wrote

As somsone who had Norovirus recently and read up on it: Alcohol Sanitisers do not kill norovirus.

Use soap and water.

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Hiddencamper t1_irn1ckm wrote

The understanding I had, was that someone with environments experience heard that and was confused because when it comes to pollution, the particle size is 100 microns that they have to worry about. It didn’t line up. And then we come to find out that medical science was potentially inconsistent here based on some specific / older assumptions.

I remember my sister, a nurse in a major Chicago hospital, telling me in April 2020 that they were finding Covid virus matter outside of patients rooms / in hallways and that didn’t make sense since it couldn’t be airborne. She was like “they keep saying it’s not airborne, but clearly something is allowing it to leave patients rooms”. The hospital at the time decided to convert all Covid floors to negative pressure after that.

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DoomGoober t1_irnmasm wrote

>The hospital at the time decided to convert all Covid floors to negative pressure after that.

Good on them. It doesn't matter what theoretical guidance the CDC is putting out or whatever the textbooks are saying. If something is observable clinically, either the text books are wrong are there's some other phenomena that's not being accounted for. Either way, take action against what you're observing.

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Hiddencamper t1_irnqpth wrote

It was crazy. The administration was adamant it wasn’t airborne. Then immediately after said they are converting. My sister was like “this is nuts….. is it airborne or not”.

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asteconn t1_irm4rmd wrote

What was the source of that error?

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DoomGoober t1_irmvr40 wrote

The original aerosol research was performed in the 1930s and the 100 micron number was correctly cited for a bit.

Years later, some research into TB discovered only the smallest particles, 5 microns and smaller, could get deep into the lungs and cause TB.

A paper mistakenly used the 5 micron number as the max size of droplets that remain in the air and other papers in public health repeated the mistake.

What's interesting is that the mistake only propagated among public health researchers. Aerosol physicists were using the right number all along and it was only when aerosol physicists started looking at SARS-CoV-2 that they noticed public health was using the wrong number.

Turns out, public health was never in the habit of talking to aerosol physicists and aersol physicists were mainly focused on pollution. It was just a weird case of siloing that the experts didn't talk to each other until a pandemic forced them to.

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Fit_Resolution237 t1_irmx55l wrote

It’s aerosol. Which I thought was different than droplets?

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DoomGoober t1_irmxpy8 wrote

The terminology is unclear, which doesn't help.

Let's just call everything a droplet and say that droplets over 100 microns tend to fall out of the air quickly and droplets under 100 microns can remain in the air for a longer time (depends on humidity and other factors, but that's the general rule.)

"Aersol", "airborne" and other terms differ in meaning depending on which specialilzed domain you are talking in.

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