Office Depot and other stores that sell storage bins and boxes also sell dessicant products (little bags of crystals or plastic boxes) to soak up humidity in the air which might lead to break down of paper, rusting of staples and paperclips, etc. They’ll work like the kitty litter without the perfumy smell. Be sure to use fresh kitty litter in your shoes–not the used kind. You can dump the kitty litter in the litter box when it stops working in your shoes, but old dessicant pouches and boxes won’t work in your litter box.