Installing air filters in classrooms has surprisingly large educational benefits (2020)

Only marginally relevant, this is one reason I use swamp coolers in my home. My windows are open 24/7, 4 months of the year. I hear the birds in the morning and it’s so much more pleasant than shutting in an air conditioned box, in my opinion

Does the humidity not cause problems? What is the relative humidity in your home?

I'd guess somewhere dry. Swamp coolers don't really work in humid climates.

Do you not get massive amounts of dust?

Why would opening the windows result in dust, except where there a lot of dust outside (near a construction site)?

swamp coolers work - imples desert - implies dust

Having any roads/cars around is a major problem. Brake and tire dust. Many people live near roads and traffic.

Unlikely to be a problem if the windows are open, in most climates.