It's prob'ly humidity/moisture more than dry air that can affect test strips. The ones sealed in foil are less apt to be exposed, and I've never had a problem opening them. There a notches along the sides of the little packets & I just tear downward from one of the notches - opens right up. I open the "working" end, so that I can insert it into the meter while still holding the foil, and the end of the strip that makes contact with the meter never touches anything else that might contaminate it. The foil slides right off once the strip is positioned in the meter.
It's possible that accuracy could fail somewhat with age, but I've tested 5-year-old strips against new ones (albeit different brands of meters), and the results were only a few points different.