Particle emission and exposure during nanoparticle synthesis in research laboratories

Real-time size, mass and number particle concentrations, and emission rates in university laboratories producing nanoparticles by scalable flame spray pyrolysis are quantified. Measurements were conducted in four laboratories using various technological set-ups and during production of particles of a range of compositions with differing physical-chemical properties, from NaCl salt, BiPO(4), CaSO(4), Bi(2)O(3), insoluble TiO(2), SiO(2), and WO(3) to composites such as Cu/ZnO, Cu/SiO(2), Cu/ZrO(2), Ta(2)O(5)/SiO(2), and Pt/Ba/Al(2)O(3). Production time ranged from 0.25 to 400 min and yields from 0.33 to 183 g. Temporal and spatial analyses of the particle concentrations were performed indicating that elevated number concentrations in the workplace can occur. Airborne submicron number concentrations increased from background levels of 2100 up to 106,000 cm(-3) during production, while the mass concentration ranged from a background of 0.009 to 0.463 mg m(-3). Maximum particle number emission rates amounted to 1.17 x 10(12) min(-1). The size distributions displayed concentration peaks mainly between 110 and 180 nm. However, changes in the operating conditions and the production of certain nanoparticles resulted in concentration peaks in the nanoparticle size range <100 nm. The effectiveness and limitations of current technology in assessing researchers' exposure to nanoparticles during production are examined, and further measures for workers' protection are proposed.