• Korean Journal of Remote Sensing
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• v.36 no.6_3
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• pp.1721-1732
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• 2020

Elementary school students spend a lot of time in a school and are more exposed to indoor air pollution. Also the students are physically growing and have a relatively high respiratory rate per unit weight compared to adults, so it is known that there is a high sensitivity to indoor air pollution. Therefore, indoor air quality in a school is becoming an important factor for the student's health. In this study, a correlation analysis using levels of indoor and outdoor Particulate Matter (PM) measured from five elementary schools in Seoul was performed to evaluate the effect of outdoor PM on indoor PM. PM ratio and indoor/outdoor (I/O) ratio were also analyzed to investigate the actual condition of indoor air quality and effect of outdoor PM on indoor PM. As a result, the correlation between indoor and outdoor PM in elementary school was more significant in PM2.5 and PM1 than PM10. In the case of I/O ratio, the I/O ratio of PM10 was higher than that of 1 in four elementary schools except SD (BB:2.21, NS: 1.67, IS: 1.73, SI: 1.17). This indicates that the activity of students has a great effect on the concentration of indoor PM10.

• Journal of odor and indoor environment
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• v.17 no.4
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• pp.346-354
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• 2018

In this study, the condition of the hazardous materials in the bus was monitored according to the ventilation mode of the air conditioning system during bus service. The bus was surveyed using the indoor air quality measurement method of public transportation vehicles within one year of delivery. We evaluate the $CO_2$ and $PM_{10}$, which are the controlled parameters in buses by the Ministry of Environment, and VOCs and HCHO, the non-controlled parameters. The $PM_{10}$ concentration increased due to outdoor air intake; however the $CO_2$ concentration was found to decrease. In addition, the concentration of VOCs and HCHO was found to decrease due to the forced ventilation system and the outdoor air intake. These results show that the concentration of the other materials except $PM_{10}$ can be changed due to the outside air concentration and forced ventilation system. Therefore, through indoor air quality characteristics of the bus according to air condition system are intended to be used as the basis of an operation manual.

• Journal of Environmental Health Sciences
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• v.36 no.5
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• pp.351-359
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• 2010

The objectives of this study were to understand the characteristics of residents in industrial areas and factors affecting exposure to the Volatile Organic Compounds(VOCs : Benzene, Toluene, Xylene) as well as to assess exposure levels according to house-type, and whether residents were indoors or outdoors. This research was designed to assess the differences in exposure levels to indoor, outdoor and personal VOCs in a case group and a control group across all areas, as well as in each different area, from May to October 2007, in. 110 residents of the G, Y and H industrial areas of the Jun-nam province. The geometric mea-levels of airborne benzene for the case group 1.31part per billion(ppb) indoor, 1.29 ppb outdoor, and 1.32 ppb for personal exposure were significantly higher than for the control group 0.99, 0.87 and 0.57 ppb, respectively. The geometric mean level for toluene personal exposure across the G, Y and H areas was 5.70 ppb for the case group and 6.31 ppb for the control group. While the outdoor level was 4.27 ppb for the case group and 5.06 ppb for the control group, The indoor level for the case group was 4.78 ppb, similar to that of the control group 4.69 ppb. The geometric mean levels for airborne xylene across the G, Y and H areas were 0.16 ppb(outdoor), 0.12 ppb(personal exposure) and 0.10 ppb(indoor) for the case group, and for the control group were 0.17(personal exposure) and 0.09 ppb(indoor and outdoor). The indoor/outdoor(I/O) ratio for case group is 1.19, while that of the control group is 1.15, indicating that the indoor level was higher than the outdoor level. The interrelationship differences among the three different types of levels in the air in the G, Y and H areas are statistically significant, except for the difference between the indoor and outdoor figures for xylene. In terms of the different types of houses and energy type uesd, the geometric mean level for airborne benzene, toluene and xylene for houses were 1.61, 5.39 and 0.12 ppb, respectively. while the figures for flats were 0.67, 3.32 and 0.05 ppb, respectively. Outdoors, the levels of benzene and toluene in flats were 0.71 and 2.62 ppb, respectively. and 1.58 and 5.35 ppb in houses. For personal exposure, the house levels of benzene, toluene and xylene were all higher than for flats. Houses using oil for heating have significantly higher levels than flats, which use gas for heating.

• Journal of Environmental Science International
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• v.19 no.1
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• pp.1-8
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• 2010

Only limited information is available on the measured exposure levels of residents according to the construction age of apartments. As such, present study was conducted to measure and to compare the bedroom, living-room, and outdoor air levels of MTBE and benzene, toluene, ethyl benzene and m,p-xylene(BTEX) in both newer and older apartments. For both newer and older apartments, all the compounds except for MTBE showed significantly higher levels in bedrooms or living-rooms as compared to the outdoor concentrations. The ratio of bedroom or living-room median concentration to outdoor concentration was close to 1 for MTBE, whereas it was larger than 1 for other target compounds. It was also found that the bedroom and living-room appeared to have similar indoor sources and sinks for BTEX, but not for MTBE. The median concentration ratios of the newer apartments to the older apartments ranged from 1.63 to 1.81, depending upon the compounds. In contrast, the MTBE concentrations did not differ significantly between the newer and older apartments, thereby suggesting that although newer buildings could emit more VOCs, this is not applicable to all VOCs. Conclusively, the findings of present study should be considered, when designing exposure studies associated with VOC emissions in buildings and/or managing indoor air quality according to construction age of buildings.

• Journal of Environmental Health Sciences
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• v.28 no.3
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• pp.39-48
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• 2002

Cooling towers water has frequently been known as a source of infection in outbreaks of Legionnaires' disease and a source of indoor air pollution. However, there have been a few reports on the presence of Legionella in cooling towers water and aerosols of various public facilities. This study was carried out to investigate the indoor and outdoor dis-tribution of Legionella spp and microbe from 132 cooling towers water of public facilities detected 1. pneumophila in Seoul and Gyeonggi-Do areas. The results showed that the Lpneumophila among the selected 132 cooling towers was detected mostly in July (12.0%), followed by August (4.0%) and June, September no-detected. The 1. pneumophiia in public facilities was detected mostly in department store (27.3%), followed by hospital (8.7%), office building (5.9%), big market (5.0%) and hotel, subway no-detected. The pH values of cooling towers water with presence of 1. pneumophila showed mostly 8.0 or higher (9.5%), followed by 7.0～8.0 (6.8%), lower 7.0 no-detected. The tem-perature of cooling towers water with presence of L pnemophila showed mostly 30℃ or higher (9.8%), followed by 26～30℃ (6.9%), lower 25℃ no-detected. The turbidity of cooling towers water with presence of 1. pneumaphila showed mostly 1-2 M (8.8%), followed by above 2 NTU (5.9%), lower 1 NTU no-detected. The correlation coef-ficient between indoor and outdoor concentration of microbes in public facilities showed 0.67 in Legionella spy. (p>0.05), 0.93 in bacteria (p<0.01), 0.94 in fungus (p<0.01), 0.98 in coilform (p<0.01), respectively.

• Journal of Environmental Science International
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• v.8 no.3
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• pp.319-323
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• 1999

This study was designed to evaluate the exposure to benzene by residents in neighborhoods near a major roadways, by persons waiting buses, and by drivers and service station attendants while refueling. It was confirmed that the outdoor air benzene concentrations near the major roadways were higher than those further away from the sources. However, neither the indoor air nor breath concentrations were different for two specified residential areas. Smoking was confirmed as an important factor for the indoor air benzene levels. Persons waiting buses, drivers and service station attendants were exposed to elevated benzene levels compared to even the residents in neighborhoods near a major roadways. The mean benzene concentration at bus stop was 2.7 to 6.9 times higher than the mean ambient air concentration. The mean benzene concentrations in the breathing zone of drivers and service station attendants were 95 to 160 and 120 to 202 times higher than the mean ambient air concentrations, respectively.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.22 no.2
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• pp.128-133
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• 2012

People are exposed to air pollution from a range of indoor and outdoor sources. Concentration of nitrogen dioxide $(NO_2)$, which is hazardous to health, can be significant in both types of environment. This paper reports on the measurement and analysis of indoor and outdoor $NO_2$ concentrations and their comparison with measured personal exposure in house and workplace indoors with 28 office workers during winter and summer seasons. Time activity patterns were used to determine the effects of these factors on personal exposure. The residential indoor and office indoor times were $12.29{\pm}1.58,$ $7.86{\pm}1.97$ hours in winter and $11.04{\pm}2.18,$ $8.26{\pm}2.04$ hours in summer, respectively. Measured residential indoor, outdoor and office indoor, personal exposure $NO_2$ concentrations were $23.10{\pm}8.46$ ppb, $23.97{\pm}6.86$ ppb, $21.91{\pm}11.50$ ppb, $22.08{\pm}8.64$ ppb in winter, and $19.94{\pm}6.04$ ppb, $21.21{\pm}6.84{\pm}$ ppb, $22.55{\pm}9.54$ ppb, $27.45{\pm}8.96$ ppb in summer, respectively. Contributions of residential and office indoor $NO_2$ concentration on personal exposure were estimated by 57.98%, 35.62% in winter and 37.38%, 28.97% in summer, respectively.

• Journal of Environmental Health Sciences
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• v.28 no.1
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• pp.85-92
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• 2002

A measurement of indoor microorganism using Reuter Centrifugal Air Sampler(RCS) was undertaken during October 1991 - February 1999 and 6-Stage Cascade Air Sampler was undertaken during May 2001 - June 2001 in Seoul. Sites including book store, department store, theater, subway station, underground shopping center, hospital, office building, sports facility, and eduationa institutio were chosen to measure indoor microorganism. The results were as follows: 1. The average of total microorganism collected on the agar strip GK-A media were, in the order, subway station, hospital, underground shopping center, department store, book store, theater, sports facility, educational institution, office building in sites. The highest concentration of 711cfu/m$^3$ was found in the subway station and the lowest concentration of 44cfu/m$^3$ was found in office building. 2. The average of staphylococci collected on the agar strip GK-S media, in the order, were subway station, underground shopping center, hospital and department store, department store, theater, office building, sports facility and educational institution in sites. The highest concentration of 502cfu/m$^3$ was found in the subway station and the lowest concentration of 14cfu/m$^3$ was found in sports facility and educational institution. 3. The average of fungus collected on the agar strip GK-HS media, in the order, were underground hospital, shopping center, theater, subway station, department store, book store, sports facility, educational institution, and office building in sites. The highest concentration of 252cfu/m$^3$ was found in the hospital and the lowest concentration of 32cfu/m$^3$ was found in office building. 4. Ratio of Indoor/Outdoor, determined by site was 1.12-2.38 in total count, 1.00-2.35 in staphylococci, and 0.99-1.34 in fungus. 5. The positive results of test were 12-24% in indoor and 9-43% in outdoor. 6. By gram staining gram positive cocci were 59.9%, gram positive bacill 24.4%, gram negative bacilli 10.4%, and gram negative cocci 0.5%.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.15 no.3
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• pp.160-165
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• 2005

Schools have significant and serious indoor environmental health problem, of which indoor air quality (IAQ) in school building may affect the health of the students and indirectly affect learning performance. Schools are of special concern when regarding indoor exposure to air pollutants, because students are particularly sensitive to pollutants and spend a significant amount of time in that environment. Therefore researches for improvement of indoor air quality have been developed such as installation of air cleaning device, ventilation system, titanium dioxide(TiO2) coating and so on. However, it is difficult to evaluate the magnitude of improvement of indoor air quality in field study because indoor air quality can be affected by source generation, outdoor air level, ventilation, decay by reaction, temperature, humidity, mixing condition and so on. In this study, evaluation of reduction of formaldehyde emission rate in school indoor environments by far-Infrared ray coating material was carried out using mass balance model in indoor environment. we proposed the evaluation method of magnitude of improvement in indoor air quality, considering outdoor level and ventilation. Since simple indoor concentration measurements could not properly evaluate the indoor air quality, outdoor level and ventilation should be considered when evaluate the indoor air quality.

• Environmental Engineering Research
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• v.18 no.3
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• pp.169-176
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• 2013

The present study was designed to examine the concentrations, emission rates, and source characteristics of a variety of volatile organic compounds (VOCs) in 30 newly-constructed apartment buildings by measuring indoor and outdoor VOC concentrations over a 2-year period. For comparison, seven villa-type houses were also surveyed for indoor and outdoor VOC concentrations over a 3-month period. Indoor and outdoor air samples were collected on Tenax-TA adsorbent and analyzed using a gas chromatograph (GC)/mass spectrometer system or a GC/flame ionization detector system coupled to a thermal desorption system. The long-term change in indoor VOC concentrations depended on the type of VOCs. Generally, aromatic (except for naphthalene), aliphatic, and terpene compounds exhibited a gradual deceasing trend over the 2-year follow-up period. However, the indoor concentrations of the six halogenated VOCs did not significantly vary with time changes. Similar to these halogenated VOCs, the indoor naphthalene concentrations did not vary significantly with time changes over the 2-year period. Unlike the halogenated VOCs, the indoor naphthalene concentrations were much higher than the outdoor concentrations. The indoor concentrations of aliphatic and aromatic compounds were higher for the villa-type houses when compared to those of apartment buildings. In addition, four source groups (floor coverings and interior painting, household products, wood paneling and furniture, moth repellents) and three source groups (floor coverings and interior painting, household products, and moth repellents) were considered as potential VOC sources inside apartment buildings for the first- and second-year post-occupancy stages, respectively.