Video showing microdroplets suspending in air
vimeo.com
vimeo.com
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.
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.
My logic for subsidizing good HVAC also applies to other pathogen mitigation technologies. No-touch sinks in public areas are one example.
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?
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.