If anything, schools able to implement air filtration and fresh air exchanges systems are likely those flush with cash and supportive parents.
If parents would be allowed to contribute towards it like a 10year bond it would pay for itself…
Would you support a small study saying a medicine or a vaccine produces a 20 year life expectancy increase, all that to end up 20 years later with no improvement, everyone on that medicine, and the anti-everything yelling on every platform that the big pharma lobby poisoned our children ?
Even when the studies are on large samples, double-blind, long time range with a clear explanation as to why there's an effect, we have people trying to kill the resulting health campaigns. Don't encourage fake ones !
There's no single party controlling 'science'. It's all just individuals many of them under 'publish or perish' rules.
You have heard of air pollution, I assume. Some schools are in places that regularly have polluted air.
It's the classic German Stoßlüften in action.
However, the air outside also has lots of dusts. Opening the windows does nothing for that, but air filtration can potentially help.
Though for us the ceremony was only one or two mild complaints from the kids near the window, and the teacher firmly stating that the room reeks of sweaty teenagers and needs some airing out.
And rain? What's the problem with opening a window when it's raining? Only if there's a rain storm... and not even then, depending on wind direction.