  The efficiency of dust formation in oxygen-rich AGB stars should (in theory)
be metallicity dependent since they are not producing their own raw material
for dust production. Metal-poor carbon stars may not be very efficient dust
producers either, because of more radiative heating of the grains forming in
their atmospheres. We have just confirmed that inefficient dust and wind
formation in simulations of metal-poor carbon stars is a real physical effect,
albeit within the limitations of our simulations. Taken at face value, this
implies that the amount of dust supplied by low-metallicity AGB stars to the
build up of the cosmic dust component is clearly limited. Consequently, one may
also ask how large a contribution AGB stars can make in general, when compared
to recent observations of cosmic dust, which are suggesting major contributions
from other sources?
