The overwhelming majority of library and archival collections are kept in storage. Paper collections themselves are a source of formic acid and acetic acid within the storage room. This paper investigates the concentration of both organic acids in three storage facilities during summer and winter as well as their temperature-related off-gassing from six paper samples in a laboratory set-up. The study reveals a basic pattern in the formation of formic and acetic acid which was notably higher in summer than in winter at all three storage sites. The temperaturedependent changes of formic acid and acetic acid level during the seasons correspond to the changes in off-gassing from the six paper samples determined at laboratory conditions. The study indicates that reducing the temperature in storage facilities of libraries and archival collections will reduce the off-gassing of organic acids from paper and by this their concentration in air.