PAH survival time against CR bombardment (ions  +  electrons) as a function of the molecule size (N_C). The total lifetime has been calculated for f = 0.5 and 1, where f is the fraction of the transferred energy available for dissociation, and adopting our reference values for the threshold energy for carbon atom ejection, T₀ = 7.5 eV and for the fragment binding energy, E₀ = 4.6 eV. We remind the reader of the variation in the calculated survival time against CRs, due to the uncertainty on the parameters E₀ and T₀ (cf. Figs. 6 and 7). The PAH lifetime against shock destruction in the ISM is shown for comparison.