

Interesting, funny enough I have sorta the opposite problem using Firefox for PDFs: I like the side by side view of two pages and Firefox always loads books with single pages, zoomed way too far in for my taste. Have you tried it for PDFs recently? It’s a new way of reading them for me, and I wonder if they’ve changed it since you used it last.
Maybe an enclosure with inlet and outlet fans, and either a window AC unit or a dehumidifier dedicated to your printing room? I definitely recommend watching this video before investing in a dehumidifier, a lot of helpful information about how humidity works: https://youtu.be/j_QfX0SYCE8