Peak flux-density measured at sub-mm/mm wavelengths vs. redshift. Triangles indicate 3σ detection limits. The deepest observed limit on the peak flux-density of GRB 120422A is displayed by the filled green triangle, while the limit from the SED modelling is highlighted by the empty green triangle. Dotted lines display flux-density levels for equal luminosity at varying redshifts. Several interesting bursts are highlighted in the figure: the high-L GRBs 030329 and 080319B and the low-L GRB 060218. Figure adapted from de Ugarte Postigo et al. (2012b).