Free the girls!
However, this article deals with what you should do with your bra after washing it.
Most bras should be washed based on the material they are made with. However, most are hand washable.
After washing and air drying them, most women stack them in their drawers or even put them in an underwear bag.
You should always hang up your bras in an aerated space, accord to The Mirror.
This is to prevent sweat and dirt from co-mingling, festering and causing irritation and unpleasant smells. You can also leave them out flat instead.