Video showing microdroplets suspending in air(vimeo.com)
vimeo.com
Video showing microdroplets suspending in air
https://vimeo.com/402577241
12 comments
To be fair, they were simulating an airtight room with zero movement.
Even just people walking around would create some airflow -- an HVAC would create both airflow and temperature gradient.
Blowing the droplets away is effective, but also blowing them in to either each other or a surface is also effective.
Evaporation also occurs -- the smallest droplets likely would evaporate long before this model shows them hitting the ground or dissipating.
To your final point, I direct you to the hygiene hypothesis -- you definitely want to periodically encounter low levels of non-lethal pathogens.
Yeah, people should take reasonable precautions when they are sick, and you should wash your hands whenever they're dirty or before you eat/stick your fingers in your nose (or at least 5x per day just on general principle), but we shouldn't stop having human social contact, and you shouldn't live in a Cleanroom.
Even just people walking around would create some airflow -- an HVAC would create both airflow and temperature gradient.
Blowing the droplets away is effective, but also blowing them in to either each other or a surface is also effective.
Evaporation also occurs -- the smallest droplets likely would evaporate long before this model shows them hitting the ground or dissipating.
To your final point, I direct you to the hygiene hypothesis -- you definitely want to periodically encounter low levels of non-lethal pathogens.
Yeah, people should take reasonable precautions when they are sick, and you should wash your hands whenever they're dirty or before you eat/stick your fingers in your nose (or at least 5x per day just on general principle), but we shouldn't stop having human social contact, and you shouldn't live in a Cleanroom.
Sure, we shouldn’t be extra paranoid and literally live in a clean room. Yes, the simulated room had zero circulation, which is unrealistic. However, the point stands that micro-droplets linger far more than you’d think. We should find ways to systematically improve the health of the population. Guidelines to cough into our elbows just don’t cut it. Flu vaccines are great but they’re not enough and they’re not universal.
My logic for subsidizing good HVAC also applies to other pathogen mitigation technologies. No-touch sinks in public areas are one example.
My logic for subsidizing good HVAC also applies to other pathogen mitigation technologies. No-touch sinks in public areas are one example.
I am really struggling to understand the recommendations for SARS-COV2 at this point.
WHO claims that the virus is transmitted via contact or heavy droplets and some other study previously linked on HN refered that aerosolization was only a risk in ICU when extubating a patient.
But this video seems to contradict that, no?
WHO claims that the virus is transmitted via contact or heavy droplets and some other study previously linked on HN refered that aerosolization was only a risk in ICU when extubating a patient.
But this video seems to contradict that, no?
The professor only said that "they're now becoming aware of the possibility of the virus being transmitted via droplets". So they're not totally sure either. It's all at an early exploratory phase.
The 1.5m distancing rule that so many governments (and sadly once more their lackey scientific experts) has very little to do with physical properties, but is chosen so as to allow for the least possible required adaptations to factories and offices.
The video shows both real sensors and a simulation showing the vast majority of particles contained in a 6-ft range and then falling to the ground.
Your observations are correct, but your implied conclusion is not.
In the 'real' environment micro-droplets are shown to be suspended for minutes. It is the larger droplets that are pulled down by gravity and do not make it far. But the micro droplets can contain more than enough virus particles.
It is shown that the room gradually accumulates more and more suspended droplets as people continuously produce them, not just through sneezing and coughing, but just by talking and breathing.
In a typical office environment there is continuous low velocity air circulation spreading these droplets through the room and saturating the whole space with them.
The video shows also that cross drafts, which produce a high air replacement, can take the droplets outside of the room which is a good thing. The moment the draft is closed the accumulation starts anew.
In the 'real' environment micro-droplets are shown to be suspended for minutes. It is the larger droplets that are pulled down by gravity and do not make it far. But the micro droplets can contain more than enough virus particles.
It is shown that the room gradually accumulates more and more suspended droplets as people continuously produce them, not just through sneezing and coughing, but just by talking and breathing.
In a typical office environment there is continuous low velocity air circulation spreading these droplets through the room and saturating the whole space with them.
The video shows also that cross drafts, which produce a high air replacement, can take the droplets outside of the room which is a good thing. The moment the draft is closed the accumulation starts anew.
Their model doesn't seem to account for static charges and evaporation, which typically results in accumulation on surfaces and less of endlessly freefloating in a room.
Isn’t that almost as bad? That means that if you don’t breath them in, they’ll have another chance of infecting you through surface contact and inevitable migration toward your face.
Not if you don't rub the walls, ceiling, and floor.
What about the other things that could be in a room? Tables, couches, food, etc...
Shouldn’t the government subsidize good HVAC (not just energy efficient HVAC)? It already subsidizes green energy, which helps avert a far off semi-existential risk. Good HVAC could partially mitigate an existential risk in the near future, in addition to loss of productivity and life due to seasonal flus. Of course, we should all be wearing masks when we go out during a pandemic. Less intuitively for people, we should expect sick individuals to wear masks outside of home regardless of a pandemic, and we should never ever physically go to work or school sick.