Distributions of hydrogen column densities for absorbers found in quasar absorption lines, from Noterdaeme et al. (2012) in blue. Overplotted in green is the kernel density estimate of absorbers in GRB sightlines. Values are taken from the compilation in Tanvir et al. (2019), along with the new values presented in this sample. We also show in the red the values derived in this work. The marginal distributions for the three samples are also shown along the left side and on the top, where the different environments probed are clearly visible in the hydrogen column densities, as previously also noted in Fynbo et al. (2009). To correct for geometric differences between GRB DLAs and QSO DLAs, we have multiplied the inferred GRB DLA N_HI by a factor of two.