Accurate theoretical or semi-empirical characterization of pneumatically generated aerosols in atomic spectrometry is important in order to know the effect of the operating conditions on drop size distribution and aerosol transport phenomena. There are some empirical models for aerosol size prediction that have never been applied in the field of atomic spectrometry. Among them are the Rizk–Lefebvre model (R–L) for concentric nebulizers and the El Shanawany–Lefebvre model (S–L) for pre-filming nebulizers. These models were evaluated under the normal operating conditions employed in atomic spectrometry. Three concentric pneumatic nebulizers with different dimensions and geometries and the single bore high-pressure pneumatic nebulizer were evaluated using different solvents (water, methanol, ethanol, 2-propanol and 1-butanol). Accurate experimental drop size distributions were obtained by means of a laser diffraction system and using recently developed software. The parameters of the equations for both models were optimized by means of a non-linear optimization code. In all cases, the modified models provided the best fit of the experimental data for all the nebulizers and solvents tested. Using the proposed models and assuming that the shape of the drop size distribution can be described by a log-normal function, the overall drop size distributions of pneumatically generated aerosols were predicted with reasonable accuracy.