Welcome to the world of mildew and mould!

A dehumidifier will help. But once the mould is into the wood or carpet, the only way to eliminate it completely is removal of all the contaminated materials.

Good ventilation also helps.
Classes in a basement?
What kind of school is this?
Our gym classes where "taught" in the basement at Chatham Central, in the previous century. Back then, children with allergies were second class citizens.

dehumdifier?? where can i get it :o
and yes not all classes only few of them are in basement.its a local school