Referring to many domestic and foreign literatures, this project has completed a draft manual for exposure control of nanoparticles in nanotechnology laboratory. The manual is divided to seven chapters, including brief introduction, risk assessment of nanomaterials ES&H and management of workers, exposure assessment of nanomaterials, exposure control of nanomaterials, fire and explosion prevention, waste management of nanomaterials and accidental release management of nano-materials. The draft manual is pending for expert review and approval. Sor far, there is no appropriate exposure assessment and control in all nanotechnology laboratories and plants, since the assimilation and training of exposure control manual has not been executed. In the future, it is suggested to promote the education traning and use of the manual for exposure control of nanoparticles in nanotechnology laboratory.
This project has conducted particle measurement in two nano-material associated laboratories and five workplaces, repectively. Among the two laboratories, particle concentration outside of the experimental chamber was found to be low, since the amount of nanomaterials used was small and the particle control system such as Hood and negative pressure chamber was well implemented. The nanoparticle mass concentration in the laboratories was nearly the same as the background value.
However, nanoparticle mass concentration in the shipbuilding palnt was highest (maximum value was 33.7 μg/m3), followed by the synthetic rubber plant (maximum value was 12.3μg/m3), and the epoxy molding compound plant and calcium carbonate plant had the lowest concentration, the maximum value of which was 3.82μg/m3 and 1.85μg/m3, respectively. Particle mass in all plants was mostly in respirable size range instead of nano-sized range. The epoxy molding compound plant had highest respirable particle mass concentration, followed by the shipbuilding plant, synthetic rubber plant and calcium carbonate powder plant had the lowest concentration. Powder dustiness test found that mass median aerodynamic diameter (MMAD) of all nano-powders belonged to micronmeter range after it was dispersed by a small scale powder disperser (SSPD). The most particle mass concentration fell in the respirable fraction; the nanosize fraction was very low. Among five tested powders (nanao-titanium dioxide, nano-zinc oxide, nano-aluminum oxide, carbon soot and iv nano-clay), nano-titanium dioxide had the smallest MMAD (1105 nm), the next was nano-zinc oxide (1344 nm), nanao-aluminum oxide (1322 nm), carbon soot (1329 nm) and nano-clay (3179 nm). Number concentration of the dispersed particles was ranked based on unit powder weight as nanao-titanium dioxide ＞ nano-zinc oxide ＞ nano-aluminum oxide＞carbon soot＞nano-silicon dioxide (HDK, N20)＞nano-clay ＞nano-silica dioxide (Degussa) in the size range of the aerodynamic particle size (APS). In the size range of the scanning mobility particle sizer (SMPS), the ranking was nano-aluminum oxide＞ nanao-titanium dioxide＞carbon soot＞nano-silicon dioxide (HDK, N20)＞nano-zinc oxide＞nano-silicon dioxide(Degussa) nano-clay. Comparing all tested powders, nano-titanium dioxide and nano-zinc oxide had the best dispersivity while nano-clay has the worst dispersity. In addition, the ranking of respirable particle mass concentration per unit dispersed powder weight was nano-titanium dioxide (highest), nano-clay, nano-silicon dioxide (HDK, N20) (lowest). In general, the dispersed nano-particle mass concentration of powders decreased with increasing powder apparent density. Since nano-silicon dioxide (HDK, N20) has the smallest apparent density, the nano-particle mass concentration per unit powder weight is higher than nano-titanium dioxide and other powers.