I read that as the only factor all three share. n=3 would of course be kinda weak for this but apparently n>3 by a lot, so ...
This sort of thing seems to be not that rare, I know of a few other ... toxic schools, including my (German) secondary school. A few years after I graduated, they roped off a building after repair workers discovered that the building was chock full of asbestos, with the stuff present in air samples as well. Officially no one knew it was there at all, and the building was built at a time when asbestos toxicity was already widely known (not yet outlawed though).
This sort of thing seems to be not that rare, I know of a few other ... toxic schools, including my (German) secondary school. A few years after I graduated, they roped off a building after repair workers discovered that the building was chock full of asbestos, with the stuff present in air samples as well. Officially no one knew it was there at all, and the building was built at a time when asbestos toxicity was already widely known (not yet outlawed though).