Deterioration of soda and potash glass is known from the study of both modern and historic glass. This is normally attributed to reactions between the glass surface and moisture in a two-stage process. The combination of Raman spectroscopy and Secondary Ion Mass Spectrometry (SIMS) can improve understanding of the chemistry of the glass alteration process. Formic and acetic acids play an important role in the alteration of museum glass objects placed in a humid atmosphere. Raman spectroscopy indicates that the soda-rich glass structure is modified differently when exposed to a humid versus a humid and polluted atmosphere at 60˚ C. Results show that volatile organic acids play an important role in the modification of soda glass in humid atmospheres. The accelerated ageing experiments indicate that the glass structure is modified differently if exposed to organic acid vapours in humid atmospheres rather than to water vapour alone. While the acid atmosphere mainly favoured and maintained the ion-exchange process, the non-polluted humid atmosphere generated a strongly alkaline solution that favoured the breakage of the silicate network. The Raman data suggest that the broken silicate network has re-polymerised into a new structure. -- ICCROM