  The presence of the dust in the circumnuclear region strongly affects our
view of the nucleus itself. The effect is strong in type 2 objects but weaker
effect is likely to be present in type 1 objects as well. In these objects a
correction to the observed optical/UV spectrum must be done in order to recover
the intrinsic spectrum of a nucleus. The approach based on the extinction curve
is convenient for that purpose so significant effort has been recently done in
order to determine the extinction curve for the circumnuclear material. It
seems clear that the circumnuclear dust is different from the average
properties of the dust in the Interstellar Medium in our galaxy: the well known
2175 A feature is weak or absent in AGN nuclear dust, and the extinction curve
at shorter wavelength does not seem to be rising as steeply. The circumnuclear
dust is therefore more similar to SMC dust, or more likely, to the dust in very
dense molecular clouds in our Galaxy. However, the exact shape of the
extinction curve in the far UV is still a matter of debate, and various effects
are difficult to disentangle.
