Paper 'breathes' 24/7/365; it constantly tries to normalize itself with the atmosphere around it. This is why a stable environment is key. Fluctuating atmospheric conditions drives paper to normalize itself quicker and more frequently. Think about it at a microscopic level, how the paper fibers are reacting to unstable, fluctuating relative humidity. One day it is 75%, a day or two later it is 50%, then back to 65%. The fibers are like a sponge, taking in moisture and expelling moisture with each atmospheric change. And along with that intake and outtake comes harmful atmospheric contaminates like carbon dioxide (acid). This constant fluctuation also consumes any 'acid free' buffers originally in the paper and will eventually exhaust the buffers and allow the paper to acidify.
Thinking that an 'acid free' paper is going to last over time is like thinking that if you take an antacid before eating a spicy meal means you will never again get heartburn from any meal in the future.
A cool, dry and stable storage environment is paramount; ideally temperatures should be held at a constant 70°F with a relative humidity held between 30% and 50%. Don
Don, I worry about this given where I live (New England) as there's quite a bit of seasonal fluctuation in temp/humidity. Can't be great for the collection/albums. Would you suggest getting something like a wine fridge to keep things at a constant temp? Of course, I still take the albums out on a pretty frequent basis, so not sure it'd matter much...