The excitation energy of O(1D) is a potentially significant heating source in the region 60--150 km. Some of the O(1D) energy is thermalized directly by collisional deactivation, some of it is radiated at 6300 and 7619 ¿ and thus lost to the atmosphere, and the rest of the O(1D) energy (about 25%) enters the near-resonant N2(v=1)--CO2(001) system. Since the atmosphere is optically thick to 4.26-&mgr;m radiation below about 80 km, the O(1D) energy that enters this N2--CO2 system and is not locally quenched is multiply scattered to other altitudes where it can be thermalized or lost out of the top of the atmosphere. Our calculations show the relative proportions of each of the O(1D) energy loss options.