Built too tight

Ventilation, that's what's important! Trust me, I know, and I've learned the hard way. I've just spent the better part of the afternoon dealing with one of the furrier problems this world has to offer: Mould. Mildew. Argh. Disgusting. I don't know who designed this appartment, but it takes one shower to steam up all the windows... especially in the wintertime. I should have known this water wasn't just going to disappear.
Today I decided to finally clean away that leftover dirt and dust where the AC had been during the summer. That was when I discovered it wasn't just dirt and dust, but mould. Yuck! And everything was wet! Big drops of water hanging everywhere! Water standing in the nooks and crannies of the window structure. Hidden behind those office-like curtain things. Trying to look innocent. Black growth everywhere.
A terrible thought dawned on me - I jumped up, ran to the living room window, moved aside the curtains: The same thing! I ran into the bedroom, ripped away the tape that holds the blinds in place, opened the metals bars, swept aside the curtains things: Mildew! Water! The worst contamination imaginable!
Slowly I went back into the living room to check the backdoor window. Yes. There, too.

I thought: Well, mildew, if you want war, you shall have war.

It took only seconds to type in the security code to open the secure kitchen cabinet where the weapons-grade cleaners are stored.
I armed myself with the deadliest window cleaner there is. The ugliest, most disgusting kind. The kind those enviromentalists really disapprove of. The kind that kills whatever it touches. If you value having fingers, never, and I repeat, never attempt to use it without rubber gloves on. If you like being able to go running again in your life, never, and I repeat, never breathe while using this cleaner.
Muahahahar!

I took two hours to clean all 3 windows and 1 windowed backdoor.
Now the mould is gone.
Fuck you, mould!
Don't you dare to come back. I have more liquid death in a bottle! You have been warned.