• KIEAE Journal
• /
• v.1 no.1
• /
• pp.35-43
• /
• 2001

The VOC, which were detected from the newly built house, exist as a certain number of types according to the characteristics of the change of VOC concentration indoors. In this paper, we aim to divide the VOC into types so that those with similar characteristics of the transition of their concentration are in the same group and select the representative compound according to each classified type, and to verify these processes statistically in order to verify and propose new method creating the representing index of the VOC concentration in indoor which is used in evaluation of the degree of air pollution. As a result, the characteristic of the change of VOC concentration in the indoor can be divided into three types. Type1; the group in which the concentration is relatively high right after the completion of the house, and then decreases rapidly. Type2; the group in which the concentration is relatively low right after the completion of the house, and then although it shows the tendency of increasing and decreasing repeatedly, it decreases overall. Type3 is the group, which show only one peak at a certain time during the measuring period. As the method like this was verified to have the statistical significance, the Ethylbenzene was selected as the representative compound of type1, and Styrene was selected as that of type2. Moreover, if considering transition of the VOC from the point of similarity, the research method of making the classification and the selection of the representative compound in this study are said to be significant method.

• Journal of Korean Society of Environmental Engineers
• /
• v.28 no.6
• /
• pp.588-595
• /
• 2006

Indoor radon($^{222}Rn$) concentrations of subway stations in Seoul area were measured to survey the environmental indoor radon levels and to identify sources of radon. The radon concentration of indoor air by method of long-term measuring with a-track detector were surveyed at 232 subway stations from 1998 to 2004. And the radon concentration in ground-water was measured with a method of alpha particle counting. To trace main source of radon, 8 out of 232 stations were selected and their radon concentrations in tunnel and on platform were analyzed. Total geometric mean and arithmetic mean of radon concentrations in all stations from 1998 to 2004 were $1.40{\pm}1.94pCi/L,\;1.65{\pm}1.07$ respectively. Geometric means of radon concentrations on platform and concourse were $1.54{\pm}1.96pCi/L,\;1.23{\pm}1.88pCi/L$ respectively, with higher concentration at the platform than at the concourse. The geological structure was significantly correlated to the indoor radon concentration in subway stations region. Radon concentrations of adjacent tunnel and ground-water of subway station was significantly correlated to the indoor radon concentration in subway stations. And There was a significant difference in radon concentration, depending on the depth levels in platform of subway stations(p<0.05).

• International Journal of Air-Conditioning and Refrigeration
• /
• v.9 no.3
• /
• pp.36-45
• /
• 2001

During the last decade, an increasing interest in Underfloor Air-Conditioning (UFAC) systems has emerged. The purpose of this paper is to evaluate the indoor environmental performance of office buildings with UFAC system in order to develope the design prototype of this system. The physical measurements and the Interviewing survey of occupant's sensation responses to the environment were carried out. Measurements and survey were made of the thermal environmental factors such as air temperature, relative humidity, air velocity, globe temperature, and the other several environmental factors such as the sound level and the illuminance of working plane, etc. And, the air quality was evaluated by measuring the concentration of suspended particles, carbon monoxide, and carbon dioxide in the room. Furthermore, the paper appraises the various indoor environmental factors of the room by using post-occupancy evaluation (POE) method in office building with UFAC system, and thus, it suggests the basic data for assessing the indoor comfort based on field measurements and survey .

• Journal of Korean Society for Atmospheric Environment
• /
• v.24 no.2
• /
• pp.153-161
• /
• 2008

The guidelines for indoor air quality of public transportations such as subway, train and bus was presented by Korean Ministry of Environment last end of year 2006 based on the great consequence of indoor air quality in daily life. Two main parameters, carbon dioxide($CO_2$) and particulate matters smaller than $10\;{\mu}m(PM_{10})$, were selected as index pollutants for the management of indoor air quality. The former pollutant, $CO_2$, is regarded as index of ventilation status and the major source of $CO_2$ in the train or subway is the exhalation of passengers. It is publically perceived that the high $CO_2$ concentration in a crowded subway will be reduced and ventilated with outdoor air by door-opening taken every 2 or 3 minutes when the train stops each station. However, there has not been any scientific proof and quantitative information on the effect of door-opening on the $CO_2$ reduction by ventilation with outdoor air. In this study, $CO_2$ concentration and number of passengers were measured at each station on the 3 lines of Korail metropolitan subway. In order to evaluate the effect of $CO_2$ reduction by door opening, the theoretical approach using the $CO_2$ balance equation was performed. By comparing the predicted data with monitoring one, the optimum $CO_2$ dilution factor was determined. For the first time, it was quantified that about 35% of $CO_2$ concentration in the subway indoor was removed by the door-opening at each station.

• Journal of Environmental Health Sciences
• /
• v.46 no.5
• /
• pp.504-512
• /
• 2020

Objective: The purpose of this study was to evaluate the indoor to outdoor ratio (I/O ratio) of time activity patterns affecting PM_2.5 concentrations in homes in Korea through a simulation. Methods: The time activity patterns of homemakers were analyzed based on the 'Time-Use Survey' data of the National Statistical Office in 2014. From September 30 to October 2, 2019, the experimenter lived in multifamily housing located in Guro-gu, Seoul. The I/O ratio of PM_2.5 concentration was measured by installing sensor-based instruments. Results: The average indoor and outdoor PM_2.5 concentrations during the three days were 33.1±48.9 and 45.9±25.3 ㎍/㎥, respectively. The average I/O ratio was 0.75±0.60. The indoor concentration tended to increase when PM_2.5 source activity such cooking and cleaning was present and outdoor PM_2.5 was supplied through ventilation. Conclusions: This study could be used as basic data for estimating indoor PM_2.5 concentrations with personal activity pattern and weather conditions using outdoor concentrations.

• Journal of Environmental Health Sciences
• /
• v.34 no.2
• /
• pp.137-147
• /
• 2008

This study evaluated the effects of the human activity and outdoor air on concentrations of size-selective particulate matters (PM) by conducting a realtime measurement in classrooms and on roofs at 4 elementary schools, 3 middle schools and 3 high schools in Incheon City. PM concentrations featured repetitive pattern of increasing during break time (including lunch hours) and cleaning time while decreasing during class hours. This trend was more prominent with inhalable PM and PM10 than fine PMs (PM2.5, PM1.0). The indoor/outdoor (I/O) ratio of inhalable PM and PM10 exceeded 1 while that of fine PMs was close to or below 1. The PM2.5 (out)/PM10 (out) ratio stood at 0.59 (${\pm}0.16$) and the PM2.5 (in)/PM10 (in) ratio was 0.29 (${\pm}0.09$), suggesting that occupant activity had a greater effect upon coarse particles (PM10-PM2.5) than upon fine particles (PM2.5, PM1.0). The correlations between the indoor and the outdoor PM concentrations showed a stronger positive correlation for fine particles than that of coarse particles. The linear regression analysis of PM concentrations indoor and outdoor indicated a higher determinant coefficient ($r^2>0.9$), and consistency for fine particles than in case of coarse particles. In conclusion, the results of this study suggest that the indoor coarse particle concentration is more attributed to occupant activity and the indoor fine particle concentration is more influenced by outdoor air pollution.

• Journal of Environmental Impact Assessment
• /
• v.10 no.3
• /
• pp.211-221
• /
• 2001

Recognizing interaction between the environment and humans, the EIA(environmental impact assessment) movement has sought to promote more environmentally sound and informed decisions for the sake of human welfare. Therefore, most EIA programs require the consideration of human health impacts. Yet relatively few EIA documents adequately address those impacts. This study was carried out to investigate the role of EIA for reuniting the environment and human health, for preventing and reducing significant health risks, and for improving human health impact assessment by means of risk assessment. Risk assessment consists of 4 components; hazard identification, dose-response assessment, exposure assessment and risk characterization. Since most people spent their times in indoor, indoor air quality modelling can be used in exposure assessment and risk assessment. In this study, indoor $NO_2$ concentration and personal $NO_2$ exposure were estimated by Box Model using mass balance equation and time weighted average, respectively. The estimated indoor $NO_2$ concentration and the personal $NO_2$ exposure were compared by those measured, respectively. Subsequntly, health effect was assessed with these results. Consequently, exposure assessment and risk assessment using indoor air quality model may be considered to be applicable to EIA.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.22 no.2
• /
• pp.128-133
• /
• 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 odor and indoor environment
• /
• v.17 no.4
• /
• pp.362-371
• /
• 2018

Indoor Volatile organic compounds (VOCs) are classified as known or possible toxicants and odorants. This study characterized VOC levels in 11 homes in an area in the capital of Seoul by using two different methods of VOCs sampling, which are the active sampling using a thermal sorption tube and the passive sampling using a diffusion sampler. When using the active sampling method, the total target VOC concentration ranged from 41.7 to $420.7{\mu}g/m^3$ (mean $230.4{\mu}g/m^3$ ; median $221.8{\mu}g/m^3$) during winter and 21.3 to $1,431.9{\mu}g/m^3$ (mean $340.1{\mu}g/m^3$; median $175.4{\mu}g/m^3$) during summer. When using the passive method, 29.6 to $257.5{\mu}g/m^3$ (mean $81.8{\mu}g/m^3$; median $49.4{\mu}g/m^3$) during winter and 1.2 to $5,131.1{\mu}g/m^3$ (mean $1,758.8{\mu}g/m^3$; median $1,375.1{\mu}g/m^3$) during summer. Forty-nine VOCs were quantified and toluene showed the highest concentration regardless of the season and the sampling method studied. The distribution of VOCs was relatively varied by using the active method. However, it showed a low correlation with indoor environmental factors such as room temperature, humidity and ventilation time. The correlation between indoor environmental factors and VOCs were relatively high in the passive method. In particular, these characteristics were confirmed by principal component analysis.

• Journal of odor and indoor environment
• /
• v.16 no.1
• /
• pp.47-53
• /
• 2017

Mold is one of the important bio-aerosols affecting human health in the indoor environment. To manage mold contamination, it is necessary to use an appropriate method for its detection and enumeration. Recently, the impaction method of ISO 16000-18 has been established as one of methods to detect and enumerate molds in air. To investigate the general use of the impaction method for mold detection in domestic indoor environments, the suitability of the method was assessed using different antibiotics, media and air samplers. All of the three antibiotics tested - ampicillin, chloramphenicol and streptomycin - showed inhibitory effects on bacterial colony formation on MEA and DG-18 media, without inhibiting mold growth. Of these three antibiotics, ampicillin was the most effective. There was no statistical difference between MEA and DG-18 media in the measurement of mold concentration. The formation of discriminative colony morphology was more apparent in DG-18 media. No significant difference in the measurement of mold concentration was found between Andersen samplers and MAS-100NT samplers, which are two major samplers introduced in Korea.