## 1 Background  
The studies, intended to identify the formation and sources of nano aerosol in the air, have been actively conducted so far by employing synthetic models enabling comprehensive measurement in terms of physical and chemical aspects [1, 2, 3]. In the chemical aspects, the aerosols in the air mainly consist of organic compounds, inorganic compounds, and trace elements [4, 5, 6]. The current level of technologies, enabled to analyze chemical substances less than approximately 10 nm to understand the formation thereof, is however quite limited yet [4, 7]. Thus, the analysis of chemical components such as nitrate ions (NO\({}_{3}\)\({}^{-}\)) of PM\({}_{2.5}\) (less than 2.5 micrometer particulate matter), created from the oxidation of primary gaseous compounds, such as NO, are being carried out, together with analyses on physical characteristics in size distribution according to varied number concentration [8, 9]. The studies associated with the source of particles, are in progress by measurement of the size distribution simultaneously conducted with analysis of mass fragments of particles evaporated at 70 eV by exploiting the real-time aerosol mass spectrometer (AMS) of a unit of second [10, 11, 12]. However, the studies inevitably exhibit limitations in identifying the sources of particles in terms of (1) the limitation in the analysis of thousands of organic compounds, and (2) rapid decrease of analytical sensitivity for particle size distributionsless than 100 nm [13]. In regard to the number concentration, over 80% of particulate matters in the atmospheric environment are related with ultrafine (<0.1 \(\upmu\)m) particles [14]. However, the hazardousness of ultrafine particles is difficult to identify since mass concentration of particulate matters in the atmospheric environment is determined by the particles of relatively bigger size based on PM\({}_{2.5}\) components analysis, or particulate matters of PM\({}_{10}\) (<10 \(\upmu\)m), identified from chemical analyses. In general, it has been reported that smaller particles, residing in the atmospheric environment, tend to exhibit higher degree of hazardousness to human health [15]. According to previously conducted study, the smaller particles appeared with higher probability of deposition in the respiratory organs of human, and were estimated to have higher accessibility to human skin as well [16]. For example, the toxic equivalency quantities (TEQ) of poly aromatic hydrocarbon compounds (PAHs) in particulate matters, to be absorbed through respiratory organs of people in the office, appeared higher in accordance with smaller particle sizes of the 0.67, 2.04, and 2.64 corresponded to particle sizes of 200-2000 \(\upmu\)m, 100-150 \(\upmu\)m, and <43 \(\upmu\)m, in the experiment [16; 17]. The issues of traffic environment, resulting from exhausts from vehicles, emerge as common issues of international community, while the United Nations Framework Convention on Climate Change including major countries promote the development of diverse policies and projects pertinent to the resolution of traffic environment. In regard to the generation of particulate matters in metropolises, the vehicle exhaust has been reported with significant contributions [18]. Since over 90% of the number concentrations of vehicle exhaust are comprised of particulate matters less than 1 \(\upmu\)m, the particulate matters in the exhaust are closely associated directly with the health of human body [19; 20; 21]. The relevance of hazardousness of vehicle exhaust to human health has been identified from several studies. According to previously conducted studies, approximately 50% of traffic volume was reduced to mitigate the effect of air pollution during the period of the 2008 Summer Olympics in Beijing. The health of adolescents in Beijing, before and after completion of the Olympics, was monitored wherefrom the negative effects of increased traffic volume were found [22].