This paper reports on the implementation of a quantitative planar laser-induced fluorescence (PLIF), which employs an absorption technique simultaneously, to assess the effect of initial diameter on the release of atomic sodium. The temporal release of the atomic sodium under fuel rich conditions was found to be different from that under fuel lean conditions, especially during the smelt coalescence stage. The total atomic sodium released and the release rate of atomic sodium increase as the initial diameter of the black liquor droplet is decreased. This highlights the role of small droplets, possibly derived from ejecta, in fume formation.