years ago before they started air conditioning schools, people used to open the windows. You don't see that happening today. We have a 2 1/2 yrs old new construction masonary public building where i live and the environmental systems stink. The building was designed by a firm that mostly build schools, in fact the building resembles one. Silica dust is probably the biggest factor its gets into everything in a new building and it stays there unless the building is superly professional cleaned and decon'ed. Everytime the heating/ac or vacummn cleaners or just general heavy foot traffic it stirrs up this stuff...and its a whole new season.
I know only because I was experiencing many of the same complaints the child in this article has. Choking wet cough, runny nose, the whole works.....was given all kinds of allergy & asthma medicines some caused even more problems. I found certain room made me react even more and those were ones that had commercial carpet and high recessed area where a regular cleaning can't be reached. It would just choke off my breathing....
Well I went and got tested for my cold like symptoms that never seem to quite go away.......and I found I was alergic to the silica dust in the building. When I avoid rooms with carpeting and those fancy recess area I find my symptoms are minor.
I worked with an old Italian stone mason years ago, on a reconstruction project. He said old stone house are the best because the stones can breath, new houses don't breath. I think he was right. We would wash the stones and flush away all the excess, kind of hard to do it in a modern building.