The production of ionization at upper E region levels at Arecibo and other low latitude sites during magnetic storms had been previously found to be associated with a few rayleighs of N2 +4278¿ emission, but it had not been possible to decide between energetic electrons, ions or neutrals as the primary particles involved. Observations of H Balmer b emission during such an event now demonstrate that energetic hydrogen atoms or protons are involved. Of these, H atoms from charge exchange of ring current protons are the more plausible explanation. Smaller contributions to the ionization and N2 + emission by other species may be present, and larger contributions to energy deposition by precipitating oxygen are probably present.