Under non-equilibrium conditions, apparent cross sections for the emission of the H&agr; line in charge changing collisions of protons in nitrogen and argon were measured in the energy range from 0.64 to 29 kev. Since emission cross sections above 10 kev are known, only our measurements below 10 kev are of importance for applications because they represent lower bounds for the unknown emission cross sections. The reduction factors for the H&agr; emission from 3S and 3D levels due to non-equilibrium conditions in the observation region of the beam were computed for our experimental conditions as a function of impact energy.