Computed half-lives for the illustrative PAH molecule naphthalene in the nuclear regions of our Seyfert galaxies. The thick line histogram is the full sample, and the filled histogram are the galaxies with a nuclear detection of the 11.3 μm PAH feature. We indicate the typical lifetimes of PAHs in the diffuse ISM (see Tielens 2013) and the timescale for PAH injection into the ISM by evolved stars (Jones et al. 1994).