Ejecta produced at or until age t by a single stellar population with an initial metallicity Z = 0.02 (in mass fraction), the Kroupa et al. (1993) IMF and Portinari et al. (1998) yields for massive stars; the fraction of close binary stellar systems is 0.05. Panel a: ejection rate in mass of ejecta per unit time per unit initial mass of the SSP: “all” denotes the sum on all ejected elements; “metals”, the sum on all metals; “α \ O”, the sum on the main α-elements except oxygen (i.e., Ne, Mg, Si, S and Ca). The bump after 1 Gyr is due to RGB stars undergoing the helium flash. Panel b: cumulated mass of ejecta per unit initial mass of the SSP.