Laser ablation of solids in gases and liquids enables the generation of nanoparticles without using any chemical precursors, resulting in pure aerosols and colloids free from by-products and additives. Examples of the generation of metal (Ag, Au, Cu), alloy (NiTi, FeNi) and ceramic (ZrO2:Y3O2, Al2O3) colloids and aerosols are given. Since the material, the size and the carrier fluid can be freely chosen, laser ablation in gases and liquids could be an appropriate tool for systematic studies on adverse health effects of engineered nanoparticles.