It is well known that nanoparticles are generated as by-products during ultrashort-pulsed laser ablation. Airborne nanoparticulate matter is well known as potential health risk when workers are exposed during operation of laser machinery. In order to provide safety-related statements on nanoparticles generated during laser micromachining, we studied the particle size distribution dur- ing picosecond (ps) and femtosecond (fs) laser ablation. At the same pulse energy, fs pulses release similar share of nanoparticles (>80\%) in the aerosol fraction, with fs compared to ps generating a far higher share 7 nm sized particles during machining of metals (steel, brass) and ceramics (zirconia). These nanoparticles sampled at the workplace have the same chemical composition than the ablated material (iron-chromium-nickel alloy, yttria-doped zirconia). A quantitative risk assessment is car- ried and compared with indicator s of toxicological effects of in haled nanoparticles. The surface equivalent of the nanoparticles dispersed in the ai r of the workplace is not likely to exceed the sur- face dose which cause inflammatory response in an imal lung. But within one 8 h shift, the back- ground level is exceeded by a factor of 20 so th at efficient fume extraction is strongly recommended for safe operation during fs and pf laser micromachining even in research laboratories.