Measurements of N2/O2 ratios inside individual air bubbles in various depths of the EDML ice core are presented here. The small bubbles (diameter below ~200 μm) in deeper ice are significantly enriched in O2 compared to the larger bubbles. The N2/O2 ratios show a systematic dependence on bubble size which is not the case for bubbles in shallower ice. This is interpreted as an effect of pressure relaxation during storage of the cores.