Accurate quantum mechanical calculations of the (J = 0) energies and lifetimes of the metastable states of ozone on a new, accurate potential energy surface are reported. These are very relevant to a famous anomalous isotope effect in the reaction that forms ozone because of their role in the energy transfer mechanism, in which metastable ro-vibrational states of ozone are formed and then stabilized by collisions with a third body. The resulting spectrum of metastable states is very dense below the delta zero-point energy threshold and sparse above it. This gives a clear qualitative explanation of why the effect occurs. (C) 2003 Elsevier Science B.V. All rights reserved.