In-Bo Oh

Surface Ozone Episode Due to Stratosphere-Troposphere Exchange and Free Troposphere-Boundary Layer Exchange in Busan During Asian Dust Events

The current paper reports on the enhancement of O, CO, NO, and aerosols during the Asian dust event that occurred over Korea on 1 May 1999. To confirm the origin and net flux of the O, CO, NO, and aerosols, the meteorological parameters of the weather conditions were investigated using Mesoscale Meteorological Model 5(MM5) and the TOMS total ozone and aerosol index, the back trajectory was identified using the Hybrid Single-Particle Lagrangian Integrated Trajectory Model(HYSPLIT), and the ozone and ozone precursor concentrations were determined using the Urban Ashed Model(UAM). In the presence of sufficiently large concentrations of NOx/, the oxidation of CO led to O formation with OH, HO, NO, and NO acting as catalysts. The sudden enhancement of O, CO, NO and aerosols was also found to be associated with a deepening cut-off low connected with a surface cyclone and surface anticyclone located to the south of Korea during the Asian dust event. The wave pattern of the upper trough/cut-off low and total ozone level remained stationary when they came into contact with a surface cyclone during the Asian dust event. A typical example of a stratosphere-troposphere exchange(STE) of ozone was demonstrated by tropopause folding due to the jet stream. As such, the secondary maxima of ozone above 80 ppbv that occurred at night in Busan, Korea on 1 May 2001 were considered to result from vertical mixing and advection from a free troposphere-boundary layer exchange in connection with an STE in the upper troposphere. Whereas the sudden enhancement of ozone above 100 ppbv during the day was explained by the catalytic reaction of ozone precursors and transport of ozone from a slow-moving anticyclone area that included a high level of ozone and its precursors coming from China to the south of Korea. The aerosols identified in the free troposphere over Busan, Korea on 1 May 1999 originated from the Taklamakan and Gobi deserts across the Yellow River. In particular, the 1000m profile indicated that the source of the air parcels was from an anticyclone located to the south of Korea. The net flux due to the first invasion of ozone between 0000 LST and 0600 LST on 1 May 1999 agreed with the observed ground-based background concentration of ozone. From 0600 LST to 1200 LST, the net flux of the second invasion of ozone was twice as much as the day before. In this case, a change in the horizontal wind direction may have been responsible for the ozone increase.

Elevated Ozone Layers over the Seoul Metropolitan Region in Korea: Evidence for Long-Range Ozone Transport from Eastern China and Its Contribution to Surface Concentrations

Abstract Elevated layers of high ozone concentration were observed over the Seoul metropolitan region (SMR) in Korea by ozonesonde measurements during 6–9 June 2003. An analysis of the synoptic-scale meteorological features and backward trajectories revealed that the layers were associated with the long-range transport of ozone from eastern China. Further examination of the long-range transport process responsible for the development of these layers was performed using the Community Multiscale Air Quality (CMAQ) model. CMAQ demonstrated that the upward mixing of ozone by convective activity in eastern China and subsequent horizontal transport aloft in the periphery of a slow-moving high pressure system led to the development of thick ozone layers over the SMR. Through comparative simulation studies, it was found that the surface ozone levels in the SMR can be significantly enhanced by the vertical down-mixing of ozone from the layer aloft with the growing mixed layer. On average, about 25% of the surface ...

Association of carbon monoxide levels with allergic diseases in children.

BACKGROUND Air pollution is regarded as a potential reason for the development or aggravation of allergic diseases. OBJECTIVE To investigate the relationship between exposure to outdoor air pollution during the first year of life and the development of allergic diseases, and to determine the association between outdoor air pollution near the residence and recent symptoms of allergic diseases in children. METHODS A nationwide cross-sectional survey was conducted in 6- to 7-year-old children. Among them, subjects who had been born (n = 1828) or lived (n = 1894) within 2 km of the nearest air quality monitoring sites were selected. The prevalence of allergic diseases was assessed by using questionnaires. Each subject was examined by pediatricians to determine the presence of eczema. Publicly available data were used regarding the daily ambient concentrations of sulfur dioxide, nitrogen dioxide, ozone, carbon monoxide (CO), and particulate matter. RESULTS For a 100 ppb increase in the mean daily CO level during the first year of life, the adjusted odds ratio for lifetime allergic rhinitis was 1.10 (95% confidence interval, 1.03-1.19). For a 1 ppm increase in the annual average CO level during the past 12 months, the adjusted odds ratio for the presence of atopic dermatitis on the day of the survey was 8.11 (95% confidence interval, 1.06-62.12). However, the other air pollutants showed no statistical significance. CONCLUSIONS Higher exposure to CO during infancy increased the risk of development of allergic rhinitis. The risk of current atopic dermatitis symptoms increased in children who were exposed to higher CO levels during the past 12 months.

High-resolution Simulation of Meteorological Fields over the Coastal Area with Urban Buildings

A meso-urban meteorological model (Urbanized MM5; uMM5) with urban canopy parameterization (UCP) was applied to the high-resolution simulation of meteorological fields in a complex coastal urban area and the assessment of urban impacts. Multi-scale simulations with the uMM5 in the innermost domain (1-km resolution) covering the Busan metropolitan region were performed during a typical sea breeze episode (4~8 August 2006) with detailed fine-resolution inputs (urban morphology, land-use/land-cover sub-grid distribution, and high-quality digital elevation model data sets). An additional simulation using the standard MM5 was also conducted to identify the effects of urban surface properties under urban meteorological conditions. Results showed that the uMM5 reproduced well the urban thermal and dynamic environment and captured well the observed feature of sea breeze. When comparison with simulations of the standard MM5, it was found that the uMM5 better reproduced urban impacts on temperature (especially at nighttime) and urban wind flows: roughness-induced deceleration and UHI (Urban Heat Island)-induced convergence.

Modeling of the Air Pollutant Recirculation using the MM5-CAMx on Ozone Episode in Greater Seoul Area during June, 2004

Recent evidence has demonstrated that the pollutant recirculation can play an important role in leading to high ozone concentrations. In this study, the MM5-CAMx air quality modeling system was applied to simulate the pollutant recirculation and identify the transport of pollution during the high event (the maximum of 195 ppb) observed in the Greater Seoul Area (GSA) on June in 2004. The results showed a weak northeasterly synoptic wind during the night and early morning moved the air parcels containing the locally emitted urban pollution to the coast, which contributed to enhance formation in the southwest part of the GSA. As the sea breeze developed and started to penetrate inland in the late afternoon, the rapid build-up of concentration was found in the southwest coastal area due to the recirculation of the polluted air loaded with high level . The simulated backward trajectories and observations at coastal sites confirmed the recirculation of pollutant with the late sea breeze is the dominant factor affecting the occurrence of high concentrations in the southwestern GSA.

Seasonal distribution of airborne pollen in Ulsan, Korea in 2009-2010

To determine the peak dispersal times of allergenic pollen grains in Ulsan, Korea, we performed continuous airborne pollen counts at three stations (Sts. A, B, and C) in Ulsan from August 2009 to November 2010. Pollen grains were sampled using a Durham sampler. Two peak pollen dispersal seasons were observed per year. The peak seasons generally coincided with the flowering period of anemophilous trees: Taxodiaceae (February), Alnus (March), Cupressaceae (April), Quercus, and Pinus (May), and with the flowering phase of herbs from August to November, e.g., Humulus, Artemisia, Gramineae, and Ambrosia from August through September. The highest concentration of airborne pollen was from Pinus (68%), followed by Quercus (15%), Alnus (6%), and Humulus (2%); whereas very low pollen concentrations were from Taxodiaceae, Cupressaceae, Artemisia, Gramineae, and Ambrosia (≤ 1% of the annual total airborne pollen concentration). Our find ings indicate that Alnus and Humulus pollen are major allergens whereas those of Pinus and Quercus are minor allergens. The concentration of Alnus pollen grains at St. C was over five times that at Sts. A and B. This finding implies that individu als living at or near St. C are exposed to high concentrations of Alnus pollen before and after March, which is the flowering period of the alder tree. From August to September, individuals living at or near St. B are exposed to high concentrations of Humulus pollen. Our study suggests that Alnus pollen may be the major aeroallergen causing pollinosis in the spring at St. C and Humulus pollen may be the major aeroallergen in autumn at St. B.

Spatial Distribution of Air Pollution in the Ulsan Metropolitan Region

The spatial air pollution distribution of the Ulsan metropolitan region (UMR) was analyzed using monitoring data and high-resolution numerical simulations. A three-year (2011~2014) analysis for the average concentrations from the 13 air quality monitoring sites in the UMR showed that SO2 and PM10 levels in industrial regions were much higher than those in other regions, whereas spatial differences of NO2 and CO concentrations were not significant. In particular, elevated O3 concentrations were clearly found at urban sites near petrochemical complex area. Results from high-resolution simulations by CMAQ model performed for four months of 2012 showed large spatial variations in grid-average pollutant concentrations between industrial areas and other areas in the UMR, which displayed significant changes with wind pattern by season. It was noted that the increases of SO2 and PM10 levels were limited in costal industrial areas or over the area nearby the sea in all seasons. Modeled O3 concentrations were quite low in industrial areas and main urban roads with large NOx emissions. However, the model presented that all pollutant concentrations were significantly increased in the urban residential areas near the industrial complexes in summer season with increase of southerly wind.

Meteorological Characteristics in the Ulsan Metropolitan Region: Focus on Air Temperature and Winds

Spatial-temporal meteorological features of the Ulsan metropolitan region (UMR) were analyzed using observations and high-resolution numerical modeling. Long-term trend analysis (1970~2013) showed a significant increase of 0.033�Cyr in the 5-year moving average temperature, although detailed short-term features varied, whereas wind speed and relative humidity over the same period displayed clear decreases of -0.007 ms and -0.29%yr, respectively. These trends indicate the effects of regional climate change and urbanization in the UMR. Seasonal variations averaged for the most recent three years, 2011~2013, showed that temperatures in three different regions (urban/industrial, suburban, coastal areas) of the UMR had similar seasonality, but significant differences among them were observed for a certain season. Urban and industrial complex regions were characterized by relatively higher temperatures with large differences (max.: 3.6�C) from that in the coastal area in summer. For wind speed, strong values in the range from 3.3 to 3.9 ms occurred in the coastal areas, with large differences clearly shown between the three regions in September and October. Diurnal variations of temperature were characterized by pronounced differences during the daytime (in summer) or nighttime (in winter) between the three regions. Results from the WRF modeling performed for four months of 2012 showed large variations in gridaverage temperature and winds in the UMR, which displayed significant changes by season. Especially, a clear temperature rise in the urban center was identified in July (0.6�C higher than nearby urban areas), and overall, relatively weak winds were simulated over urban and inland suburban regions in all seasons.

Prevalence of Children's Allergic Diseases in Ulsan: Local Differences and Environmental Risk Factors

Objectives: This study aims to investigate the AD (allergic diseases: asthma, allergic rhinitis and atopic dermatitis) prevalence among elementary schoolchildren in an industrial city, Ulsan, and identify major environmental risk factors associated with AD prevalence. Methods: Data on the physician-diagnosed prevalence over the past 12 months and potential risk factors of AD were collected through a questionnaire from a 2009-2010 survey of 4,067 schoolchildren living in different urban environments. The logistic regression analysis was performed to assess differences in AD prevalence among the areas and to determine which environmental factors impacted AD. Results: Our survey results showed that the AD prevalence rate ranged between 26.2% and 35.9%. Children living in polluted areas (near industrial and central urban areas) had about a 10% higher prevalence of AD than did those living in coastal or suburban residences. The Chi-Square test demonstrated that this local difference was statistically significant before and after adjustment of major confounders such as parental AD history and parental education. The results of the logistic regression analysis showed a statistically significant association between several environmental factors (ventilation in winter, odor conditions and exposure to traffic smoke, and outdoor pollution) and the prevalence of AD found by multivariate model after adjusting confounders. Conclusion: These results suggest that local differences in AD prevalence are significantly associated with outdoor environmental factors. Although there are likely to be other risk factors for AD, living in a polluted area and exposure to high levels of air pollutants can contribute to an increased risk of childhood AD.

House Dust Mites and Associated Environmental Factors in Homes of Atopic Children: a Case-Control Study

Department of Environmental Health, Graduate School of Public Health, Seoul National University, Seoul, Korea*Environmental Health Center, College of Medicine, University of Ulsan, Ulsan, Korea**Department of Occupational and Environmental Medicine, College of Medicine, University of Ulsan, Ulsan, KoreaABSTRACTObjectives: The purpose of this study was to determine house dust mite concentrations in living rooms andbedding materials in atopic case-control groups. Methods: Fifty four homes with children suffering atopic diseases as cases and fifty one homes without atopicdiseases as controls were selected after diagnosis at three elementary schools in Ulsan City. Dust samples werecollected from the living rooms and bedding materials in each home during summer and winter with a vacuumcleaner and analyzed for house dust mites using enzyme-linked immunosorbent assay (ELISA). Environmentalfactors and family history were surveyed during sampling. Results: Both species of house dust mite Dermatophagoides farina (Der f 1) and Dermatophagoidespteronyssinus (Der p 1) were found in all homes. Derf1 concentrations were much higher than Der P1concentrations, both in atopic homes (1518.9 vs. 27.0 ng/g. dust, respectively) and non-atopic homes (810.8 vs.44.3 ng/g. dust, respectively). Der f 1 concentrations were significantly higher in the atopic group than in thenon-atopic group (atopic: 1518.9 ng/g.dust, non-atopic: 810.8 ng/g.dust, p = 0.035). However, total house dustmite Der p 1 concentrations were significantly higher in the non-atopic group than in the atopic group (atopic:27.0 ng/g.dust, non-atopic: 44.3 ng/g.dust, p = 0.035). Multiple regression implied that mothers with familyhistory of atopic diseases (OR = 4.79, 95% CI = 1.81-12.69), Der f 1 concentrations (OR = 1.74, 95% CI = 1.07-2.81), and air freshener use (OR = 4.60, 95% CI = 1.72-12.34) had significant associations with atopic children. Conclusion: House dust mite Der f 1 concentrations were associated with atopic children. This study suggeststhat parents should reduce house dust mite Der f 1 concentrations through environmental controls. Keywords: case-control, atopic disease, house dust mite, environmental factor, allergen