Around 2001 at the University of Maryland I started noticing that the pages of library books now had white powder on them, something entirely new in my long experience of using libraries.
The powder came off on my hands when I turned pages, and since I didn't know what it was, it greatly changed my relationship with library books. I no longer handle library books in bed. After handling a library book for half an hour or so I normally wash my hands — having any perceptible substance on my hands makes it hard for me to study.
This powder is magnesium oxide, whose alkaline and desiccant properties are apparently intended to slow the disintegration of wood-pulp paper, in which acid forms through the breakdown of lignin.