[O I] 63 µm emission toward G31.388-0.383. For each spectrum, we show the average of all data (black). We only show the [C II] 158 µm emission for reference in pixel 1, as the other pixels are closer to the central beam than for [C II] 158 µm and do not overlap. Several pixels show residual low-frequency baseline ripples. The gray-shaded region around 25 km s^-1 is masked due to residual artefacts from atmospheric corrections.