Evolution of the N/O for a spherical gaseous distribution of constant density with an initial metallicity of 12 + log (O/H) = 8.0 and log (N/O) =  −1.6, which is polluted by the stellar winds coming from a stellar cluster with Z = 0.004. To the left, we show the effects of a cluster of mass log (M/M_⊙) = 7 for different radii of the distribution. To the right, we show the effects of clusters of different stellar masses on a gaseous distribution with a radius of 1 kpc. Stellar wind yields were taken from Mollá & Terlevich (in prep.).