Scott Semans writes:

Climate and Humidity
Vintage editions are especially susceptible to minor fluctuations in temperature and humidity. To deter from disintegration or flaws in the paper or binding, keeptemperatures between 65-70 degrees Fahrenheit, with humidity levels at a steady 30-50 percent. Rooms with temperature and humidity controls are commonly used in libraries to storeolder artifacts, and can help preserve their condition for a longer period of time. But if you are looking to store these items in your own home, look for rooms with minimalwindows and exposure to the natural elements, and invest in a dehumidifier to keep moisture levels at a low and constant level.

Dry heat can also become an issue, causing leather covers to crack and book glue to dry out, changing the form and appearance of rare novels. To help prevent these issues andmonitor the humidity levels in your home, a hygrometer can be used to ensure ideal conditions that will keep your books in prime condition for years to come.

To read the complete article, see:
How to Store, Preserve, and Care for Rare Books(https://www.invaluable.com/blog/how-to-preserve-rare-books/)