Lyα equivalent width, EW_Lyα, vs. nebular extinction, E(B − V). Points are coloured according to ${\sigma }_0^{\text{obs}}$ as indicated by the colour bar on the right. Different symbols indicate the kinematical classes of the galaxies introduced in Sect. 3.2. The dotted blue line indicates the zone of EW_Lyα ≤ 20 Å and E(B − V)≤0.4 discussed in the text. There is no correlation between both quantities (τ = −0.049/p_τ = 0.7).