3 ms·

>Even outside, you would need shade (perhaps canopies?) and fans. I imagine fans may be problematic due to the way COVID19 primarily spreads. You might be able

>Even outside, you would need shade (perhaps canopies?) and fans. I imagine fans may be problematic due to the way COVID19 primarily spreads. You might be able to design your way out of it with clever fan and student placement but without that, you might create highways for the virus to spread from one student to the next.

AstralStorm 6y ago
Well, a ceiling fan producing laminar flow is very likely to limit the spread. Side fans and windows, unlikely. The have been a few good studies of airflow dynamics. Ultimately the best cheapest defense building wise would be airflow over 12 CFM in a top to bottom way. This is essentially an air curtain strength. That's rather expensive and takes a lot of big fans or very strong HVAC system with many air outlets. Being outside only works as long as you can spread people out heavily enough. It's better than unventilated buildings, but the benefit is overshadowed by density or distance. (See: Florida beach policy and cases after the delay.)
- rossdavidh 6y ago
  Having worked in semiconductor fabs with laminar flow, I can say that it dries your eyes out if you're not wearing goggles.
megameter 6y ago
The spread can be bisected into two parts: 1. Droplets directly exhaled. This is the stuff that you mask for. 2. Particles suspended in air. This is why staying indoors is particularly dangerous; it tends to hang around and build up without being vented. The virus dies quickly outside of droplets and in direct sunlight: this is why being outside is low risk given masks and distancing. Either it's coughed on you, or it dies within minutes. An indoors area that circulates its air quickly is almost as good, provided UV is part of the process. Fans are mostly a good idea in this respect and one could imagine an indoors "UV gate" through which air is pushed to disinfect it. I would not be surprised if the idea already exists.

AstralStorm 6y ago

Well, a ceiling fan producing laminar flow is very likely to limit the spread. Side fans and windows, unlikely. The have been a few good studies of airflow dynamics. Ultimately the best cheapest defense building wise would be airflow over 12 CFM in a top to bottom way. This is essentially an air curtain strength. That's rather expensive and takes a lot of big fans or very strong HVAC system with many air outlets. Being outside only works as long as you can spread people out heavily enough. It's better than unventilated buildings, but the benefit is overshadowed by density or distance. (See: Florida beach policy and cases after the delay.)

rossdavidh 6y ago
Having worked in semiconductor fabs with laminar flow, I can say that it dries your eyes out if you're not wearing goggles.

megameter 6y ago

The spread can be bisected into two parts: 1. Droplets directly exhaled. This is the stuff that you mask for. 2. Particles suspended in air. This is why staying indoors is particularly dangerous; it tends to hang around and build up without being vented. The virus dies quickly outside of droplets and in direct sunlight: this is why being outside is low risk given masks and distancing. Either it's coughed on you, or it dies within minutes. An indoors area that circulates its air quickly is almost as good, provided UV is part of the process. Fans are mostly a good idea in this respect and one could imagine an indoors "UV gate" through which air is pushed to disinfect it. I would not be surprised if the idea already exists.