O₃ profiles for varying N₂O and O₃ levels for planets around the Sun and the M5V hosts. The stratosphere (white background) and troposphere (gray background) are indicated in order to draw attention to differences in O₃ production and depletion with the two stellar hosts. While at higher O₂ levels the Sun-hosted planet efficiently destroys stratospheric O₃, the M5V-hosted planet experiences minimal stratospheric O₃ depletion at all O₂ levels. The smog mechanism dominates in the lower atmosphere for the two hosts, especially at lower O₂, but it is restricted to the troposphere for the planet around the Sun. Smog O₃ is produced into the stratosphere for the planet around the M5V host, due to the lack of suppression the Sun-hosted planet experiences in the NO_x-saturated regime. See Figs. 1 and 5 for more information on the NO_x-limited and NO_x-saturated regimes.