Laboratory kinetic studies suggest that an appreciable fraction of the ozone produced by recombination of atomic oxygen is vibrationally excited in the v3 mode. Further, laboratory data are available for the physical quenching of v3, its radiative relaxation, and its radiative excitation by resonant absorption. It is shown that these chemical and physical processes are likely to result in substantial departures from local thermodynamic equilibrium for the v3 mode of ozone in the mesosphere and therefore have important effects on infrared mesospheric ozone measurements by emission in the 9.6-μm band. Implications of these effects upon the Limb Infrared Monitor of the Stratosphere data, particularly their night/day ratio, are discussed.