This story might be of interest here. Ages ago one of our neighbors back home was a WWI vet whom I'd see walking around the neighborhood just about daily. He once stopped and recited his experience with the 1918 influenza pandemic during training while serving in the army.
As the influenza pandemic was ravaging, he said that the sergeant of his barracks where he was stationed did something different that all the others. To prevent flu spread, rather than keeping all the windows shut as was so common (to keep the germs out!), the sergeant had all the windows left open so there was plenty of fresh air.
And because of that our old neighbor says, the men from his barracks avoided being infected like almost all the others.
It might seem ridiculous now, but I can't tell you how many disagreements I have had with others in the past who felt that keeping windows shut (and interiors stuffy) kept disease out. They just felt that cool outdoor air brought in disease, like some kind of fresh air phobia, I guess!