  It is still an unresolved problem how much AGB stars can contribute to the
overall gas and dust enrichment processes in the interstellar medium within
galaxies. We start tackling this problem, by using our test case observational
data from the Large Magellanic Cloud (LMC), from which we obtain the global gas
and dust budget. The photometric data from the LMC is obtained with the Spitzer
Space Telescope. We established an infrared colour classification scheme to
select AGB stars, which are based on spectroscopically identified AGB stars. We
further confirm a correlation between the Spitzer colour and mass-loss rate,
which leads to a measurement of the total mass-loss rate from the entire AGB
population in the LMC. Indeed, AGB stars are an important gas and dust source.
