Relative attenuation coefficient due to the cleaning process, as a function of redshift for each Planck-HFI band. This is computed for two input SEDs modelled by a modified blackbody (T_xgal = 30 K and 40 K, with β_xgal = 1.5) embedded in foreground emission equally balanced between CIB and Galactic cirrus. It is shown for two extreme cases of the CMB template quality, i.e., ideal (upper panel) or highly contaminated by extragalactic foregrounds at small angular scales (lower panel).