  Local field effects on the rate of spontaneous emission and Lamb shift in a
dense gas of atoms are discussed taking into account correlations of atomic
center-of-mass coordinates. For this the exact retarded propagator in the
medium is calculated in independent scattering approximation and employing a
virtual-cavity model. The resulting changes of the atomic polarizability lead
to modifications of the medium response which can be of the same order of
magnitude but of opposite sign than those due to local field corrections of the
dielectric function derived by Morice, Castin, and Dalibard [Phys.Rev.A 51,
3896 (1995)].
