In this study, the formation of nanoparticles by a reaction of ozone with the volatile organic compounds(VOCs) emitted from a commercial home cleaner liquid was investigated using a $1-m^3$ reaction chamber($1{\times}1{\times}1m$). The home cleaner liquid was found to contain many VOCs, particularly terpenes. Some of these VOCs are known to readily react with ozone, forming indoor secondary pollutants. The correlation of particle concentration and reacted ozone concentration was examined with injections of three different ozone concentrations; 50, 100 and 200 ppb. The secondary nanoparticles were formed faster, with their numbers and mass concentrations becoming higher on increasing the concentration of ozone injected.

The effects of different transient loading conditions on xylene removability and bacterial activity were evaluated in the polyurethane (PU) biofilter inoculated with Rhodococcus sp. EH831: BF1 (the control) was operated under continuous and constant loading ($200{\pm}50ppm$); BF2 under continuous and constant loading after a 2-week long-term shutdown; BF3 under discontinuous (8 h on/16 h off on weekdays and a 2 day-shutdown at weekends); and constant loading BF4 under discontinuous and high loading ($700{\pm}300ppm$); and BF5 under continuous and fluctuating loading (high loading for 8 h and low loading ($75{\pm}25ppm$) for 16 h on weekdays and low loading at weekends). Xylene removal efficiencies in the BF1, BF2, BF3, and BF5 were ranged 83-89%, indicating that 2-week long-term shutdown, intermittent or fluctuant loading condition did not significantly influence the biofilter performance. However, discontinuous and high load condition (BF4) caused to deteriorate xylene removability to 52%. Rhodococcus sp. EH831 could be maintained at $10^9{\sim}10^{10}CFU/g-dry$ PU under 5 kinds of loading conditions. The result of polymerase chain reaction-terminal-restriction fragment length polymorphism showed that there was no significant change in bacterial community structures by different loading conditions.

The spatial distributions of air pollutants, in particular, ultrafine particles near traffic congestion roads at urban areas need to reduce human exposure levels for protecting public health. In this study, the number concentrations of ultrafine particles larger than 5 nm were measured every second during driving on the major roads of Nowon-gu, Seoul for 1.6 h using a mobile emission laboratory on October 5, 2010. The ultrafine particle number concentrations ranged from 7,009 to $265,600particles/cm^3$ with an average of $55,570particles/cm^3$, and these levels were comparable to concentrations of ultrafine particles larger than 3 or 7 nm on the arterial roads at urban areas in Los Angeles, USA and Zurich, Switzerland. It was frequently observed that the ultrafine particle number increased rapidly when vehicle speed was accelerated and it decreased sharply when vehicle speed was decelerated. The high peak events of ultrafine particle concentration larger than $200,000particles/cm^3$ were observed seven times during the measurement period. From the three repeated measurements during the short period of 50 min, it was concluded that the ultrafine particle number concentration on the road was significantly time-dependent. This on-road measurement approach can be utilized to manage vehicle-related air pollution in urban.

The hourly volatile organic compounds(VOCs) concentrations between 2005 and 2008 at Bulgwang photochemical assessment monitoring station were investigated to establish a method for quality assurance and quality control(QA/QC) procedure. Systematic error, erratic error, and random error, which was manifested by outlier and highly fluctuated data, were checked and removed. About 17.3% of the raw data were excluded according to the proposed QA/QC procedure. After QA/QC, relative standard deviation for representing 15 species concentrations decreased from 94.7-548.0% to 63.4-125.8%, implying the QA/QC procedure is proper. For further evaluation about the adequacy of QA/QC procedure, principal components analysis(PCA) was carried out. When the data after QA/QC procedure was used for PCA, the extracted principal components were different from the result from the raw data and could logically explain the major emission sources(gasoline vapor, vehicle exhaust, and solvent usage). The QA/QC procedure based on the concept of errors is inferred to proper to be applied on VOCs. However, an additional QA/QC step considering the relationship between species in the atmosphere needs to be further considered.