Some studies have found associations between the exposure of nanoparticle and adverse health effects due to bounded trace elements, metals as well as organic carbon on nanoparticles (Donaldson et al., 2002; Oberdörster et al., 2005). Therefore, it is important to measure the concentration of nanoparticles accurately and then quantify its chemical compositions. However, there hasn’t been any research team who is able to sample and analyze all chemical species for nanoparticles. The sampling sites were chosen based on the exposure likelihood of the city residents, students, drivers, tourists as well as workers. Thus, a road side of Poai Street in Hsinchu, Syueshan highway tunnel in Taipei, Experimental Forest of NTU in Nan-Tou and the ambient air or exhaust ducts of four nanopowder or high-tech factories were selected. This study not only used the best instruments and techniques to sample and analyze nanoparticles at different atmospheric conditions but also corrected the sampling artifact through the modification of the sampling devices and adopted of a strigent QA/QC procedure. By the comparison of measured results between different instruments, this study proved that the samples of nanoparticle could be collected precisely and the chemical compositions could be determined reliably, including OC (organic carbon), EC (elemental carbon), water-soluble ions and elements. The present results are useful to the studies of nanoparticle exposure and nano-toxicology.
The road side sampling and chemical analysis showed the day average concentration of PM0.1 was 1.97±0.59 g/m3 and the most aboudent species was the OM (organic mass, roadside OM=1.6*OC, tunnel OM=1.4*OC, forest OM=2.1*=OC) which accounted for 38.7±3.3% PM0.1. The Ions were the second majority species of particles, accounting for 23.2±9.3% of the mass. The EC and Elements were 15.9±3.2% and 16.1±7.5% of the mass, respectively. The highway tunnel sampling and real-time measurements showed the concentration of nanoparticles at daytime (9am-9pm) was 32.2±6.5 g/m3 (average of three hours) while it decreased to 10 m/m3 during midnight (0am-6am) and increased to more than 40 g/m3 (average of three hours) during the rush hour on holidays. The OM and EC were the majority of PM0.1 mass in the tunnel, which were 31.4±5.1% and 27.8±5.4%, respectively. PM0.1 of the NTU Experimental Forest was as low as 0.65±0.3 g/m3. Meanwhile from the real-time size distribution of nanoparticles, it was found photoreaction formed nanoparrticles below 10 nm during the sunny noon. The OM and Element were the major mass of PM0.1 in the forest, which were 24.1±3.0% and 14.2±3.5%, respectively. The unknown of 40% PM0.1 mass is suspected to be water.
This study also reviewed the latest literatures to bridge the knowledge gaps on measurement and characterization methods of nanomaterials and wrote eight reports on different topics, including “developing the assessment methods of the toxicity of manufactured nanomaterials in water”, “developing the reference nanomaterials for the toxicity test” and “nanomaterials measurement in the environment”, etc. Two meetings were held to discuss these eight topics and the comments from the participating experts were collected. We made concrete suggestions based on the reviewed reports and the comments of the experts on both the technical and policy aspects of the nanotechnology knowledge gaps. It is hoped this report is useful to the agencies concerned with nanotechnology EHS.