The goal of this article is to provide results on aerosol particles emissions of a laser Nd:YAG cutting technique used for the decommissioning of nuclear facilities. In particular, the study aims at characterizing the aerosol emitted during the cutting of steel specimens of different thicknesses and to study particulate emissions for cuts in air and under water. To do so, we calculate the emitted aerosol mass per unit area of cut. Overall, it was found that the mass of aerosol per unit area of cut by laser cutting decreases when the laser power and cutting speed increase. We also examine the performance of the height of the water column above the cut on the particle collection efficiency. We found that the driving phenomenon for particle collection is the scrubbing of particles by bubbles present in the water column. When cuts are realized under water, the production of aerosol particles mass per unit area of cut is reduced by a factor of 10 and limited below 70 g m–2.