The material exposure tests have been carried out since 1993 to evaluate the relationship between air pollution and material corrosion with the cooperation of the researchers in Japan, China, and Korea. The test pieces such as bronze, copper, marble, and carbon steel have been exposed under both unsheltered and rain-sheltered outdoor condition separately at 18 sampling sites in East Asia. At the same time, the concentration of SO$_2$ and NO$_2$ has been measured simultaneously with passive sampler. The meteorological data were collected from the AWS (Auto-mated weather station) In each country and chemical compositions of wet deposition were also analyzed by the bulk sampling of rainfall every month. As the results, it was found that the corrosion rates of test pieces in the ambient air were appeared to be in the order of carbon steel > marble > bronze copper. The corrosion rates of test pieces in the unsheltered outdoor condition were 2.34 to 5.88 times larger than those in rain-sheltered condition. It was also found that the corrosion rate in the heavy polluted area in China was the highest, and the corrosion rates of the metal pieces were generally proportional to SO$_2$ concentration. Between two sites in Korea, the test pieces at Daegu site showed higher corrosion rates that would be due to the higher SO$_2$ concentration.

The atmospheric pollution distribution in the industrial area of Yosu in Korea is calculated using numerical model and the model is validated by comparing the calculations with observed data. The emission of NO$_{x}$ and SO$_{x}$ was estimated for 6 sources, and the emission amount of HC was estimated for 9 anthropogenic sources. The calculated wind speed, wind direction and temperature agreed well with the observed data at two observatories, and the calculated concentration of NO, NO$_2$, $O_3$ and SO$_2$ were also reasonable for 5 monitoring stations. The validity of the model is evaluated using 3 indexes of the EPA, and the model is found to be valid and accurate.ate.

Variational data assimilation, which is recently introduced to the air quality modeling, is a promising tool for obtaining optimal estimates of initial conditions and other important parameters such as emission and deposition rates. In this paper. two advanced techniques for variational data assimilation, based on the adjoint and quasi-inverse methods, are tested for a simple air quality problem. The four-dimensional variational assimilation (4D-Var) requires to run an adjoint model to provide the gradient information in an iterative minimization process, whereas the inverse 3D-Var (I3D-Var) seeks for optimal initial conditions directly by running a quasi -inverse model. For a process with small dissipation, I3D-Vu outperforms 4D-Var in both computing time and accuracy. Hybrid application which combines I3D-Var and standard 4D-Var is also suggested for efficient data assimilation in air quality problems.

The present study details air pollution measurements in the Yellow Sea of East Asia. Large-scale air pollution was observed through satellite images and ground monitors in Chongju-Chongwon of central Korea. Evidence of a duststorm transport and resulting dustfall from the Gobi Desert in north China and Mongolia is shown. Also, transport of anthropogenic air pollutants from China to the Yellow Sea, Korea, and Japan was detected and discussed. It was found that the level of air pollution concentrations at a regional back-ground site increased 2 ∼ 4 times than the values observed with the relatively clean air, when massive air pollution from China moved to the Korean Peninsula. Satellite measurements will be useful for monitoring regional- and global-scale air pollution in the future.

Ambient polycyclic aromatic hydrocarbons (PAHs) were measured during the winter and summer of 2002 in Chongju. A filter pack and polyurethane foam (PUF) system was employed to collect simultaneously the particulate and gas phase PAHs. The samples were then analyzed using a gas chromatograph equipped with mass spectrometer detectors (GC/MSD). A total of 29 samples were collected and 11 PAH species were identified. The lower molecular weight PAH compounds (3∼4 rings) dominated the total PAH mass. The higher molecular weight PAH compounds (5∼6 rings) were less abundant. The PAHs were showed to exhibit seasonal variations. The concentrations of all com-pounds were significantly higher in winter than summer. The lower molecular weight PAHs were mostly found in the gas phase whereas the heavier ones were mainly associated with particulate phase. Vehicle emissions are likely to be the primary contributor of PAHs in Chongju. This study also demonstrated that it is necessary to perform simultaneously particulate and gas phase measurements to determine the accurate concentrations of ambient PAHs.