<p>This study addresses design validations of a developed Cascade Andersen Sampler (CAS), resolving long standing challenges such as flow maldistribution and non-uniform particle deposition observed in coarse size segregating stages in traditional CAS. Modifications in design to correct these flaws feature a 90° inlet flow path and reduced plenum volume within inlet were successfully done. Design optimisations also includes, increase in nozzle’s Reynolds number from 84 to 110 and nozzle throat length (1.3 to 3&#xa0;mm) for prominent impaction. The developed sampler has provision and is tested for dual collection surfaces, i.e. a petri plate and a flat plate. Experimental evaluations using polydisperse dust particles in a wind tunnel revealed D₅₀ cut-off variations across different collection surfaces (petri plate and flat plate) and stages. D₅₀ cut-off, defined as 50% collection efficiency corresponding to aerodynamic particle size, serves as a key indicator for sampler’s size segregation ability for a defined particle size. For the petri plate configuration, experimental D₅₀ values deviated by an average of ± 7% from theoretical values for all six stages. Whereas the flat plate configuration exhibited a slightly lower deviation of ± 6.4% on an average from theoretical values. Visual observations for enhanced deposition due to modifications described above lead to correcting flow maldistribution and minimising particle re-entrainment for coarse size segregating stages. Field evaluation for total mass concentration comparisons of the developed sampler with an eight-stage cascade Andersen sampler (commercial) shows a minor deviation of 4.8% for 5 sampling events. Additionally, stage wise mass concentration for developed CAS (before and after modifications) aligns well with the commercial sampler (reference) for particle size distribution (PSD) measurements in collocating sampling.</p> Graphical Abstract <p></p>