Distributions of host interstellar reddening E(B − V) for type Ia SNe originating from different layers in the dust disc of a LT (B/T = 0) galaxy, with vertical positions z = {0, h_d, 2h_d}. The distributions are computed for edge-on (left panel), face-on (middle panel) and random (right panel) orientations of the galaxy disc with respect to an observer. The parameters of the dust disc are summarised in Table 1. The results demonstrate that the distribution peak (the most probable reddening) depends strongly on the SN’s vertical position in the disc; the distributions are unimodal with maximum at E(B − V) > 0 for z ≲ h_d and monotonically decreasing, with maximum at E(B − V) = 0 for z > h_d.