The probability of chemical processes grows according to the rise of the moisture of materials particularly in case of the growth of the temperature of the environment since molecules of water exist in chemically active state in paper, leather and other library materials at the temperature of over 25 degrees centigrade. When the temperature is lower, the molecules of water remain inert, but there still is danger of the biological damage to documents. In the cold season moisture in the depositories is 10 to 20 per cent below the norm. However, in the summer time the temperature is as high as 30 degrees in some depositories. Sudden overfalls of temperature and moisture are to be observed at the turn of seasons and notably at the start and the end of the cold season.
Glare is another factor of adverse impact on the documents.
Solar and day light in a large measure consists of rays of this section of this spectrum. Thus the storage of documents in the dark and the paying of special attention to the conditions of exposition of document at exhibitions are preferable. The intensity of the light in the depositories of the RSL practically on all tiers exceeds the standard established for the spring and summer. Lack of plafonds on the daylight lamps very unfavourably tells on the preservation of books. Air in depositories contains multifarious admixtures for from being safe for materials of library documents.