Expected contribution to scattering at 1370 MHz for different lens DMs from an FRB host galaxy at z_H = 1 and an intervening galaxy halo within the line of sight. The solid lines show the expected host galaxy contribution for different electron density variations and a geometric boost factor G_sc = 1. The dashed lines show the expected contribution from an intervening galaxy halo with a thickness L = 30 kpc and ${\stackrel{\sim }{F}}_0={10}^{-4}$ pc^−2/3 km^−1/3 located at different redshifts. The orange shaded region represents the observed Apertif τ_sc range.