This study assessed the relationships between levels of $PM_{10}$ and hospitalization rates for asthma among children from 2003 to 2005 at four major cities in Korea. In addition, we estimated the reduced number of asthma hospitalization associated with an ambient $PM_{10}$ improvement to the acceptable levels as recommended by the World Health Organization (WHO). The Generalized Additive Model (GAM) was used to estimate the relative risks (RR) of asthma hospitalization associated with changes in $PM_{10}$ The RRs of children's asthma hospitalization for every $10{\mu}g/m^3$ increment in $PM_{10}$ were 1.009(95% CI = 1.004-1.014) in Seoul, 1.013(95% CI = 1.006-1.021) in Incheon, 1.009(95% CI = 1.002-1.016) in Busan, and 1.021(95% CI = 1.005-1.037) in Ulsan. We assessed $PM_{10}$ related health benefits from implementing the WHO's guidelines (24-hour average $50{\mu}g/m^3$) using the U.S. Environmental Protection Agency's Environmental Benefits Mapping and Analysis Program. The estimated benefits were 439(95% CI = 216-666) reduced asthma hospitalization in Seoul, 720(95% CI = 304-1,151) in Incheon, 260(95% CI = 66-459) in Busan, and 126(95% CI = 30-228) in Ulsan. It was concluded that improving $PM_{10}$ condition to the WHO guideline would make a significant contribution to the reduction in asthma hospitalization among children. Therefore, public health measures are still needed to improve air quality in Korea.

This study was conducted in industrial area. The level of nitrogen dioxide was measured indoor, outdoor, work and personal in an study area within 5 km from source of pollution and control area 15 km farther from August, 2006 to September. The followings are the summary of this research. The concentration of the indoor and the outdoor $NO_2$ levels in the industrial area are 18.41$\pm$6.35 ppb, 18.51$\pm$3.26 ppb each, and the indoor/outdoor concentration rate is 0.99. The concentration of $NO_2$ in the workplace is 18.59$\pm$10.16 ppb, and the individual exposure rate is 18.80$\pm$5.71 ppb. The concentration of the indoor and the outdoor $NO_2$ levels control area are 12.57$\pm$3.82 ppb, 9.68$\pm$2.16 ppb each, and the indoor/outdoor concentration rate is 1.33. The personal exposure rate is 14.49$\pm$10.06 ppb. The residents of the each area and those of the comparative area spend 80.9% and 76.9% each their time in the indoor. It shows they spend most of their time in indoor. The predictions of the individual exposure rates in the industrial area and the comparative area are 15.10$\pm$6.14 ppb and 10.52$\pm$3.82 ppb each, The concentration levels measured by passive sampler are 18.80$\pm$5.71 ppb and 14.49$\pm$10.34 ppb each. The result of the research is the analysis of the personal exposure rate in indoor, outdoor and workplace of industrial area. This research may bo used as a basic data to manage and to establish the plan for $NO_2$ gas of the industrial area.

The Asian dust storms which originated in the deserts of Mongolia and China transported particles to Korea and led to a high concentration of atmospheric particulate matters (PM) of more than $1000{\mu}g/m^3$ throughout the country in the spring, of 2007. Public concern, in Korea, about the possible adverse effects of these dust events has increased, as these dust storms can contain various air pollutants emitted from heavily industrialized eastern China. The objectives of this study were to understand the concentration characteristics of PM as a function of particle size between the Asian dust storm episodes and non-Asian dust period and to consider the mass size distribution of PM in the Asian dust storms and their water soluble ion species on the potential, possible effects on deposition levels in the three regions (nasopharyngeal, tracheobronchial, and alveolar) of the human respiratory system. The size distribution of PM mass concentration during the Asian dust storms showed a peak in the coarse particle region due to the long-range transport of soil particles from the deserts of Mongolia and China, which was identified by HYSPLIT-4 model for backward trajectory analysis of air arriving in the sampling site of Iksan. During the non-Asian dust period, there were two different types in PM size distribution: bimodal distribution when low concentrations of $PM_{2.5}$ were observed, while unimodal distribution having a peak in fine particle region when high concentrations of $PM_{2.5}$ were showed. This unimodal distribution with high concentrations of fine particulate and secondary air pollutants such as ${SO_4}^{2-}$, ${NO_3}^-$, ${NH_4}^+$ was found to be due to the long-range transport of air pollutants from industrialized eastern China. During the Asian dust storms, the mean concentrations of PM that can be deposited in the nasopharyngeal, tracheobronchial, and alveolar region were $128.8{\mu}g/m^3$, $216.5{\mu}g/m^3$, and $89.6{\mu}g/m^3$, respectively. During the non-Asian dust period, the mean concentrations of PM that can be deposited in the nasopharyngeal, tracheobronchial, and alveolar region were $8.4{\mu}g/m^3$, $9.5{\mu}g/m^3$ and $38.5{\mu}g/m^3$, respectively.

Hand-washing has been recognized as a critical factor in controlling infection and cross-contamination. This study was performed to investigate hygienic behavior of male university students focusing on awareness of hand-washing, their hand washing practices, and the difference between their awareness and practices. Both a self-administered questionnaire survey and a separate direct observation in restrooms were carried out at a university campus over a four week period. In the survey, 93.6% of the responded students claimed to wash their hands after using toilet. However, just 16.9% of the observed students actually did so, according to a separate and unnoticed observational study. Among the observed students who washed their hands, 25.0% of them used soap, only 5.0% of them washed four parts of their hands, and 15.0% of them washed their hands for more than 10 seconds. Paper towel was the most common hand drying method in the direct observation and also in the survey. Significant differences between the questionnaire survey and the direct observation (p<0.0l) were found in hand-washing practices, duration of hand-washing, using soap, washing parts of the hand, and hand-drying method after using the toilet. This study indicates that there is a remarkable difference between the male university students' awareness of hand-washing and their hand-washing practices. This study reveals that there is the need for programs or campaigns to increase hand-washing practices of male university students.

In recent years, pharmaceuticals in the aquatic environment have become a matter of increasing public concern. Environmental risk assessment (ERA), including an exposure assessment, is considered the best scientifically based approach for evaluating the potential effects of pharmaceuticals on ecosystems. Computerized exposure models constitute an important tool in predicting environmental exposures of pharmaceuticals. This paper presents the applicability of an exposure model by comparing measured data of selected pharmaceuticals with predicted environmental concentrations from an exposure model. $PhATE^{TM}$ (Pharmaceutical Assessment and Transport Evaluation) model developed by the Pharmaceutical Research and Manufacturers of America (PhRMA) was adapted to run simulations for the Keum River. A set of 7 pharmaceuticals of high production in Korea was modeled. The PECs generated by the $PhATE^{TM}$ model that were then compared to the measured concentrations. The $PhATE^{TM}$ model predicted concentrations for 7 pharmaceuticals including acetaminophen, acetylsalicylic acid, erythromycin, ibuprofen, lincomycin, mefenamic acid, and naproxen were in good agreement with actual measured concentrations, which demonstrated the utility of $PhATE^{TM}$ as a predictive tool. In conclusion, $PhATE^{TM}$, although it does not intend to accurately represent reality, could be utilized for rapid predictions of the environmental concentrations of pharmaceuticals.

In order to treat the complex wastewater containing organic compound and solids, pre-treatment system associated with molecular separation process were investigated. The reductions of COD and turbidity were obtained after coagulation processes using Alum (Aluminium sulfate, $Al_2(SO_4)_2{\cdot}18H_{2}O$) and PACl (poly aluminium chloride as 17% $Al_{2}O_{3}$). The results of study were as follows: using variable dosage of Alum, COD removal was highest at 4,000 mg/l, and the reduction of COD and turbidity was 42% and 92%, respectively. The optimum coagulation would be effective at pH 7.3 than pH 9.0 by the addition of alum at a concentration of 6,000 mg/l and PACl was add at 4.25% in raw complex wastewater with 2,000 mg/l alum at pH 7.3, the reduction of COD was reduced by 32%. But coagulation aid experiments indicated that PACl would be more effective in sludge separation ability than COD removal efficiency.

This study investigated improvement to sludge dewaterability and coagulation for sewage treatment plant sludge by using sodium hypochlorite solution (NaOCl), ferric sulfate [$Fe_2(SO_4)_3$] and zeolite. The specific resistance to filtration(SRF), chloride, pH and turbidity were used to evaluate the sludge dewatering behaviors. The results of study were as follows: By varying the amount of NaOCl added the optimum result in terms of enhancement for pretreatment occurred when 34 mg/l of NaOCl was injected. When the total solids concentration of the sludge was 10,000 mg/l, the optimum ferric sulfate dosage for the sludge dewaterability was 150 mg/l and the corresponding SRF was $1.7{\times}10^7sec^2/g$. It was observed that injecting zeolite into sludge was effective in improving the dewaterability of sludge.

The aims of this study is to examine the effects of the changes in HRT(Hydraulic Retention Time) and media charge in a water-mill, among other operation factors, on the nitrogen and phosphorus removal in order to use up-flow anaerobic reactors, anoxic reactors and water-mill aerobic reactors for sewage treatment. The extension of HRT improved the nitrogen removal efficiency, however the removal pattern was constant regardless of HRT. The removal of phosphorus was constant (80%-90%) regardless of the change in HRT. The removal rate with change in influx load varied such that at the OLR (Organic Load Rate) of 1-3 kg/d, the T-N removal efficiency was 80.7%-88.9% and the T-P removal efficiency was 82.9%-89.3% while at the NLR (Nitrogen Loading Rate) of 0.108-0.156 kg/d the removal efficiencies were 80.7-88.9% (T-N) and 82.9-89.3% (T-P). The analyses of the nitrogen and phosphorous removal characteristics with the C/N and C/P ratio showed that the mean T-N removal rate was 88% at the C/N ratio of 1.2-2.6, and that the mean T-P removal rate was 86% at the C/P ratio of 7.2-14.1. Also, the analysis of nitrogen and phosphorous removal characteristics were analyzed in relation to media charge. The comparison between with and without media charge in the water-mill showed that while the nitrogen removal efficiencies were 86-94% and 85-89% respectively, the difference of phosphorous removal efficiencies were between the two conditions was not significant, thus it suggested that the media charge has less effect on the removal efficiency of phosphorous compared to that of nitrogen.