Atomic hydrogen abundances as function of Rosseland mean optical depth for an atmosphere with T_eff = 19 000 K and B = 437 MG. Upper panel: fraction of neutral atoms calculated with (blue line) and without (red line) magnetic-field effects on the ionization equilibrium. Lower panel: abundance of atoms in n = 2 state in absence of magnetic field (red line) and disaggregated into sublevels when the field is present (solid blue lines for spin-down and dashed blue lines for spin-up states). Abundances of $2p_{-1}(m_s=+\frac{1}{2})$ and $2p_{+1}(m_s=-\frac{1}{2})$ states are equal (lowest solid line).