  This paper compares reddening values E(B-V) derived from the stellar content
of 103 old open clusters and 147 globular clusters of the Milky Way with those
derived from DIRBE/IRAS 100 micron dust emission in the same directions. Star
clusters at |b|> 20 show comparable reddening values between the two methods,
in agreement with the fact that most of them are located beyond the disk dust
layer. For very low galactic latitude lines of sight, differences occur in the
sense that DIRBE/IRAS reddening values can be substantially larger, suggesting
effects due to the depth distribution of the dust. The differences appear to
arise from dust in the background of the clusters consistent with a dust layer
where important extinction occurs up to distances from the Plane of ~ 300 pc.
For 3 % of the sample a significant background dust contribution might be
explained by higher dust clouds. We find evidence that the Milky Way dust lane
and higher dust clouds are similar to those of several edge-on spiral galaxies
recently studied in detail by means of CCD imaging.
