Gong-Unn Kang

Mass Concentration and Ion Composition of Size-segregated Particulate Matter during the Non-Asian Dust Storm of Spring 2007 in Iksan

In order to further determine the mass concentration and ion composition of size-segregated particulate matter (PM) during the non-Asian dust storm of spring, (fine particle), (coarse particle), and (PM with an aerodynamic diameter larger than ) were collected using a MCI (multi-nozzle cascade impactor) sampler of a three-stage filter pack in the spring season of 2007 in the Iksan area. During the sampling period from 5 April to 21 April, a total of 34 samples for size-segregated PM were collected, and then measured for PM mass concentrations by gravimetric measurements and for water-soluble inorganic ion species by using ion chromatography. Average mass concentrations of , , were , and , respectively. On average, accounted for 74% of . Compared with the literature from other areas in Korea, the measured concentration of were relatively high. Water-soluble inorganic ion fractions in , , and were found to be 47.8%, 28.5%, and 14.7%, respectively. Among the water-soluble inorganic ion species, , and were the main components in , while dominantly existed in both and . Non-seasalt (nss- and were found to mainly exist as the neutralized chemical components of and in fine particles.

Association between Scrub Typhus Outbreaks and Meteorological Factors in Jeollabuk-do Province

Objectives: Scrub typhus is one of the most prevalent vector-borne diseases. It is caused by Orientia tsutsugamushi, which is transmitted when people are bitten by infected chigger mites. This study aims at quantifying the association between the incidence of scrub typhus and meteorological factors in Jeollabuk-do Province over the period 2001-2015. Methods: Reported cases of scrub typhus were collected from the website of the Disease Web Statistical System supported by the Korea Centers for Disease Control and Prevention (KCDC). Simultaneous meteorological data, including temperature, rainfall, relative humidity, and sunshine duration were collected from the website of the National Climate Data Service System by the Korea Meteorological Administration. Correlation and regression analyses were applied to identify the association between the incidence of scrub typhus and meteorological factors. Results: The general epidemiological characteristics of scrub typhus in Jeollabuk-do Province were similar to those nationwide for sex, age, and geographical distribution. However, the annual incidence rate (i.e., cases per 100,000) of scrub typhus in Jeollabuk-do Province was approximately four times higher than all Korea`s 0.9. The number of total cases was the highest proportion at 13.3% in Jeonbuk compared to other regions in Korea. The results of correlation analysis showed that there were significant correlations between annual cases of scrub typhus and monthly data for meteorological factors such as temperature and relative humidity in late spring and summer, especially in the case of temperature in May and June. The results of regression analysis showed that determining factors in the regression equation explaining the incidence of scrub typhus reached 46.2% and 43.5% in May and June. Using the regression equation, each 1oC rise in the monthly mean temperature in May or June may lead to an increase of 38 patients with scrub typhus compared to the annual mean of incidence cases in Jeollabuk-do Province. Conclusion: The result of our novel attempts provided rational evidence that meteorological factors are associated with the occurrence of scrub typhus in Jeollabuk-do. It should therefore be necessary to observe the trends and predict patterns of scrub typhus transmission in relation to global-scale climate change. Also, action is urgently needed in all areas, especially critical regions, toward taking steps to come up with preventive measures against scrub typhus transmission.

Seasonal Characteristics of Atmospheric PM 10 and PM 2.5 in Iksan, Korea

The seasonal characteristics of atmospheric particulate matter (PM) were evaluated through the measurement of (particles with an aerodynamic diameter of less than 10 ) and (particles with an aerodynamic diameter of less than 2.5 ) collected in the downtown area of Iksan city over roughly two weeks in each season of 2004. During the sampling period, 54 samples of and were collected and then measured for mass concentrations of PM and its water-soluble inorganic ion species. The concentrations of and were highly variable on a daily time scale in all seasons, especially in fall. Annual concentrations of and were and , respectively. The daily concentrations of the analyzed ions similarly showed a pronounced variation, although a difference between seasons existed. Among them, , and were the most abundant ions in all seasons, contributing up to 32% of and 39% of . The contribution of and showed a seasonal variation, as was the highest during spring and summer and was the highest during fall and winter. Non-seasalt and were found to exist mainly as neutralized chemical components of and due to the high concentration of in PM samples, which were a major form of airborne PM in all seasons. Seasonal characteristics of and in Iksan were described in relation to the temporal variations of daily concentration of PM and its inorganic ion species including inter-particle reactions.

Concentration Characteristics and Health Effect Assessment of Atmospheric Particulate Matters During Asian Dust Storm Episodes

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 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 were observed, while unimodal distribution having a peak in fine particle region when high concentrations of were showed. This unimodal distribution with high concentrations of fine particulate and secondary air pollutants such as , , 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 , , and , respectively. During the non-Asian dust period, the mean concentrations of PM that can be deposited in the nasopharyngeal, tracheobronchial, and alveolar region were , and , respectively.

Concentration Characteristics of Atmospheric PM 2.5 , PM 10 and TSP during the Asian Dust Storm in Iksan Area

The concentration characteristics of atmospheric particle matters (PM) including , and TSP were evaluated through the measurement data of (fine particulate), (coarse particulate), and collected using a MCI (multi-nozzle cascade impactor) sampler of a three-stage filter pack in spring of 2006 in Iksan area. During the sampling period of 10-15 March and 24 days from 8 April to 2 May, 32 samples for PM of each size fractions were collected, and then measured for PM mass concentrations and water-soluble inorganic ion species. Average concentrations of , TSP were , , and , respectively. Water-soluble inorganic ion fractions to PM mass were found to be 36.5%, 18.0%, and 11.1% for , and , respectively. By showing the high concentrations of PM samples during Asian dust events, those three fractions of PM were distinguished between the samples of Asian dust event and the samples of no event. However, the increase of PM concentrations observed during Asian dust events showed a different pattern for some Asian dust events. The differences of those three fractions in the size distribution may depend on differences on place of occurrence of Asian dust storm and course of transport from China continent to Iksan area in Korea. However, the extent of PM mass contribution during Asian dust events was generally dominated by the coarse particles rather than the fine fraction of PM. The variations of water-soluble inorganic ion species concentration in those three PM fractions between the samples of Asian dust event and the samples of no event were also discussed in this study.

Differences in agricultural activities related to incidence of scrub typhus between Korea and Japan

OBJECTIVES The purpose of this study was to establish a basis for improving or strengthening the preventive strategy against scrub typhus in Korea by comparing and analyzing the difference of prevention behaviors contributing to the occurrence of scrub typhus in Japan and Korea. METHODS The survey was carried out in Jeollabuk-do, which is a high risk and high incidence area, and Fukuoka Prefecture, which is a high risk and low incidence area. The study included 406 Korean farmers and 216 Japanese farmers. Data were collected through face-to-face surveys by interviewers who had completed standardized education. RESULTS Korean farmers have a higher percentage of agricultural working posture that involved contact with weeds than Japanese farmers (p<0.05). The frequency and proportion of weeding were lower in Korean farmers than in Japanese farmers (p<0.05). The level of knowledge about scrub typhus was significantly higher among Korean farmers than among Japanese farmers (p<0.05). Mostly, the behavior of agriculture work was more appropriate for Japanese farmers than for Korean farmers (p<0.05). The total average level of agricultural work was lower in Korea than in Japan, lower in men than women, and lower in part-time farmers than full-time farmers (p<0.05). CONCLUSIONS This study suggests that it is reasonable to develop and provide a program that can improve the level of preventive behavior taking into consideration the characteristics of the subject in order to reduce the incidence of diseases in high-risk areas for scrub typhus.

Seasonal Deposition Characteristics of Water-soluble Ion Species in Ambient Aerosol in Iksan City

Objectives: This paper aims to investigate the seasonal deposition characteristics of water-soluble ion species by comparing the deposition amount of two samples taken according to different sampling methods of deposition for ambient aerosol such as gases and particulate matters. Methods: Deposition samples were collected using two deposition gauges in the downtown area of Iksan City over approximately two weeks of each season in 2004. The type of deposition gauges consisted of two different sampling methods known as dry gauge and a wet gauge. The dry gauge was empty and used a dry PE bottle with an inlet diameter of 9.6 cm. Before the beginning of each deposition sampling, a volume of 30-50 ml distilled ionized water was added to the wet gauge to wet the bottom during the sampling period. Deposition samples were measured twice per day and analyzed for inorganic water-soluble ion species using ion chromatography. Results: The daily deposition amounts of all measured ions in the dry gauge and the wet gauge showed a significant increase when precipitation occurred, having no difference of deposition amount between in the wet gauge and in the dry gauge. By excluding two samples from rainy days during the sampling period, the mean daily deposition of all ions in dry gauge and wet gauge were 6.58 mg/m 2 /day and 18.16 mg/m 2 /day, respectively. The mean deposition amounts of each ion species were higher in the wet gauge than in the dry gauge because of the surface difference of the sampling gauge, especially for NH4 + and SO4 2. The mean deposition amounts of NH4 + and SO4 2in the wet gauge were found to be about 15.4 times and 5.2 times higher than that in dry gauge, with a pronounced difference between spring and summer, while the remaining ion species were 1.1-2.0 times higher in the wet gauge than in the dry gauge. Dominant species in the dry gauge were Ca 2+ and NO3 , accounting for 36.4% and 18.1% of the total ion deposition, whereas those in the wet gauge were NH4 + and SO4 2, accounting for 32.5% and 25.0% of the total ion deposition, respectively. Conclusion: The seasonal differences in deposition amounts of water-soluble ion species in ambient aerosol depending on the two types of different sampling methods were identified. This suggests that the removal of ambient aerosol is strongly influenced by the weather conditions of each season as well as the condition of earth’s surface, such as dry ground and water.

Chemical Composition of Respirable PM 2.5 and Inhalable PM 10 in Iksan City during Fall, 2004

Intensive measurements of airborne respirable and inhalable were conducted in the downtown area of Iksan city. The and samples were collected twice a day in the Iksan city of Korea from October 17 to November 1, 2004. The purpose of the study was to determine the inorganic water-soluble components and trace elements of and in the atmospheric environment and estimate the contribution rate of major chemical components from a mass balance of all measured particulate species. The chemical analysis for PM samples was conducted for water-soluble inorganic ions using ion chromatography and trace elements using PIXE analysis. The mean concentrations of respirable and inhalable were and , respectively, and the ratio was 0.62. The ion species of , , and were abundant in both and . These components predominated in respirable fraction, while , , mostly existed in coarse particle mode. Elemental components of S, Cl, K, and Si were abundant in both and . These elements, except for Si, were considered to be emitted from anthropogenic sources, while Si, Al, Fe, Ca existed mainly in coarse particle mode and were considered to be emitted from crustal materials. The averaged mass balance analysis showed that ammonium nitrate, ammonium sulfate, crustal component, and other trace elements were composed of 18.4%, 13.2%, 4.8%, 3.5% for PM2.5 and 17.0%, 11.6%, 13.7%, 4.4% for , respectively.