Books, like people, are healthier when well supplied with good, fresh air

ManyBooks.net has a neat digitized copy of an old book entitled Book Repair and Restoration: A Manual of Practical Suggestions for Bibliophiles, Including Some Translated Selections from Essai sur l'art de Restaurer les Estampes et les Livres, par A. Bonnardot, Paris 1858 (1918), written by a British fellow named Mitchell Buck. Among the suggestions:

"Books in closed cases should be removed and thoroughly dusted at least once a year, the tops especially being carefully wiped clean, if gilt, or brushed, if uncut, in either case while holding the book tightly closed. They should be aired at the same time, particularly those not in frequent use. For this airing and cleaning a warm, sunny day should be selected and, whenever possible, on such days the cases should be opened; books, like people, are healthier when well supplied with good, fresh air."