Novel active personal nanoparticle sampler for the exposure assessment of nanoparticles in workplaces.

A novel active personal nanoparticle sampler (PENS), which enables the collection of both respirable par- ticulate mass (RPM) and nanoparticles (NPs) simultaneously, was developed to meet the critical demand for personal sampling of engineered nanomaterials (ENMs) in workplaces. The PENS consists of a respirable cyclone and a micro-orifice impactor with the cutoff aerodynamic diameter (dpa50 )o f 4μm and 100 nm, respectively. The micro-orifice impactor has a fixed micro-orifice plate (137 nozzles of 55 μm in the inner diameter) and a rotating, silicone oil-coated Teflon filter sub- strate at 1 rpm to achieve a uniform particle deposition and avoid solid particle bounce. A final filter is used after the im- pactor to collect the NPs. Calibration results show that the dpa50 of the respirable cyclone and the micro-orifice impactor are 3.92 ± 0.22 μm and 101.4 ± 0.1 nm, respectively. The dpa50 at the loaded micro-Al2O3 mass of 0.36�3.18 mg is shifted to 102.9�101.2 nm, respectively, while it is shifted to 98.9�97.8 nm at the loaded nano-TiO2 mass of 0.92�1.78 mg, respectively. That is, the shift of dpa50 due to solid particle loading is small if the PENS is not overloaded. Both NPs and RPM concentrations were found to agree well with those of the IOSH respirable cyclone and MOUDI. By using the present PENS, the collected samples can be further analyzed for chemical species concentrations besides gravimetric analysis to determine the actual exposure concentrations of ENMs in both RPM and NPs fractions in workplaces, which are often influenced by the background or incident pollution sources.