When I was a JET, one of the biggest complaints I hear from my fellow JETsters was that their clothes, futons, blankets, etc., all get moldy. Of course, being in Japan humidity is a given. However, with Toyama located on the Western, i.e. wet, side of the Japanese Alps, I remember the humidity was much much worse there. After all, average rainfall in Toyama is almost 3 times much as rainfall in Seattle!
Of course there are plenty of dehumidifiers around, some come by themselves, some built into the AC. They use up lots of electricity, and thus can be costly. But there's also this nifty electric free dehumidifier that comes in a portable plastic box the size of my hand. Now I need to emphasize that these are budget items (about 150yen/3-pack) and I have no idea how environmentally friendly they are. That said, using up tons of electricity is not environmentally either :P
So these plastic boxes have 2 compartments inside: an empty bottom compartment and an upper compartment containing white dry silica beads of sorts. Actually, I'm not certain they're silica, but they sure look it and I've never tried to pry one open to look. The instructions on the aluminum seal say to peel the seal off but to not break open "moisture-permeable trim" underneath, so I didn't try, not wanting to ruin it. Even if I did, I wouldn't be able to tell if that stuff is silica anyway.
Here's the white "moisture-permeable trim" underneath the aluminum seal.
Get rid of the aluminum seal and that's it, and the electric free budget portable dehumidifier is ready to be placed anywhere you wish to keep dry. I had tons of these around my JET days apartment in Takaoka and nothing in my possession was ever moldy. Here I popped 2 in my closet, 2 in the sleeping area, 2 in the main room and 2 in the foyer right outside of the bathroom.
How does this plastic box work? Well, whatever those white dry beads are, they draw moisture out of the air and into the box, storing the water at the empty compartment at the bottom. The beads melts as they collect water, so after a few months or so, you'll have to check if the beads are gone and the water below is full and replace the box as needs be. To get rid of the box, poke a big hole on the white trim, dump the water out, then toss the plastic box into its proper bin.
Of course the apartment can still get very damp, especially after it rains cats and dogs, so don't expect any miracles with these boxes but in general, they're pretty neat stuff.
Look, mine's already collected about 1cm of water after sitting for 3 weeks! And this is just 1 out of the 8 I have out!