Fraction of self-absorbed 63 μm [OI] line flux due to foreground material as a function of the galaxy SFR as predicted by our model. Solid lines refer to median trends while the shaded area are the 16th to 84th percentile dispersion. The solid line refers to the fiducial model, while the dashed one is obtained without considering the condition on velocity in Eq. (4). The yellow dashed region represent the typical values adopted in observational studies (reduction by a factor of two to four).