  This paper is concerned with the stability issue in determining absorption
and diffusion coefficients in photoacoustic imaging. Assuming that the medium
is layered and the acoustic wave speed is known we derive global H\"{o}lder
stability estimates of the photo-acoustic inversion. These results show that
the reconstruction is stable in the region close to the optical illumination
source, and deteriorate exponentially far away. Several experimental pointed
out that the resolution depth of the photo-acoustic modality is about tens of
millimeters. Our stability estimates confirm these observations and give a
rigorous quantification of this depth resolution.
