Cosmic rays ionize the atmosphere and can produce changes in atmospheric chemistry, with consequences for ozone protection, lightning, and possibly could cover, precipitation, and temperature. With the large increases in cosmic ray flux that are possible with nearby supernovae, neutrons, normally only a concern at airplane altitudes, may be abundant on the ground. Muons initiated by cosmic rays normally provide a large fraction of our penetrating radiation dose on the ground. With cosmic ray spikes, this may increase by a factor of one hundred or more. We have produced tables which enable the computation of atmospheric ionization, and neutron and muon fluxes on the ground from primaries up to a million Gev. We have been applying these tables to concrete situations. are seen in various papers. For our most recent work see papers on nearby supernovae. The tables themselves are available for free download at this site.