In this article, the author talks about how important disinfection is in library settings. Preventive disinfection is carried out in order to prevent the spread of infectious disease agents mainly in places of human accumulation. Disinfection is also very necessary in book stores, where one of the main paper breakers is micromycetes (microscopic mushrooms, in the home called mold). Paper is an easily available organic carbon source. The number of microorganisms capable of destroying paper is very large. In a library environment, this ability of microorganisms is causing enormous harm. Micromycettes strike intertwined and non-intertwined documents on paper and parchment, handwritten books and printed editions. It is important to withstand the temperature and humidity regime correctly, as a certain ratio of temperature to humidity can accelerate or slow the development of micromycets.