• Asian Journal of Atmospheric Environment
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• v.10 no.2
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• pp.67-79
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• 2016

The forecasting of air pollution is an important and popular topic in environmental engineering. Due to health impacts caused by unacceptable particulate matter (PM) levels, it has become one of the greatest concerns in metropolitan cities like Karaj City in Iran. In this study, the concentration of $PM_{2.5}$ was predicted by applying a multilayer percepteron (MLP) neural network, a radial basis function (RBF) neural network and a Markov chain model. Two months of hourly data including temperature, NO, $NO_2$, $NO_x$, CO, $SO_2$ and $PM_{10}$ were used as inputs to the artificial neural networks. From 1,488 data, 1,300 of data was used to train the models and the rest of the data were applied to test the models. The results of using artificial neural networks indicated that the models performed well in predicting $PM_{2.5}$ concentrations. The application of a Markov chain described the probable occurrences of unhealthy hours. The MLP neural network with two hidden layers including 19 neurons in the first layer and 16 neurons in the second layer provided the best results. The coefficient of determination ($R^2$), Index of Agreement (IA) and Efficiency (E) between the observed and the predicted data using an MLP neural network were 0.92, 0.93 and 0.981, respectively. In the MLP neural network, the MBE was 0.0546 which indicates the adequacy of the model. In the RBF neural network, increasing the number of neurons to 1,488 caused the RMSE to decline from 7.88 to 0.00 and caused $R^2$ to reach 0.93. In the Markov chain model the absolute error was 0.014 which indicated an acceptable accuracy and precision. We concluded the probability of occurrence state duration and transition of $PM_{2.5}$ pollution is predictable using a Markov chain method.

• Journal of Preventive Medicine and Public Health
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• v.46 no.1
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• pp.10-18
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• 2013

Objectives: We investigated the association between particulate matter less than $10{\mu}m$ in aerodynamic diameter ($PM_{10}$) exposure and non-accidental mortality in Asian populations by meta-analysis, using both time-series and case-crossover analysis. Methods: Among the 819 published studies searched from PubMed and EMBASE using key words related to $PM_{10}$ exposure and non-accidental mortality in Asian countries, 8 time-series and 4 case-crossover studies were selected for meta-analysis after exclusion by selection criteria. We obtained the relative risk (RR) and 95% confidence intervals (CI) of non-accidental mortality per $10{\mu}g/m^3$ increase of daily $PM_{10}$ from each study. We used Q statistics to test the heterogeneity of the results among the different studies and evaluated for publication bias using Begg funnel plot and Egger test. Results: Testing for heterogeneity showed significance (p<0.001); thus, we applied a random-effects model. RR (95% CI) per $10{\mu}g/m^3$ increase of daily $PM_{10}$ for both the time-series and case-crossover studies combined, time-series studies relative risk only, and case-crossover studies only, were 1.0047 (1.0033 to 1.0062), 1.0057 (1.0029 to 1.0086), and 1.0027 (1.0010 to 1.0043), respectively. The non-significant Egger test suggested that this analysis was not likely to have a publication bias. Conclusions: We found a significant positive association between $PM_{10}$ exposure and non-accidental mortality among Asian populations. Continued investigations are encouraged to contribute to the health impact assessment and public health management of air pollution in Asian countries.

• Journal of Environmental Science International
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• v.30 no.10
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• pp.789-802
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• 2021

This study analyzed the characteristics of high PM_2.5 episodes that meets the concentration criteria of Emergency Reduction Measures Plan (ERMP) in Busan during the 2015-2020, and compared with those in Seoul. As a first step, the CAPSS-2017 emission data was employed to analyze the emission differences between Busan and Seoul, and pointed out that Busan emission included the dominance of ship emissions (37.7%) among total PM_2.5 city emissions, whereas fugitive PM_2.5 emission was the highest in Seoul. These emission characteristics are indicating that the controlling action plan should be uniquely applied to cope with ERMP in each region. We selected extremely high PM_2.5 episode days that meet the criteria of ERMP levels. In Busan, Ulsan, and Gyeongnam region, 15, 16, and 8 days of extremely high PM_2.5 cases were found, respectively, whereas Seoul showed approximately doubling of occurrences with 37 cases. However, the occurrences in summer season indicated big differences between two cities: the proportion of summer-season occurrence was 13-25% in Busan, whereas no single case have occurred in Seoul. This is suggesting the needs of comprehensive summer emission reduction plan with focusing on sulfur reduction to effectively cope with the ERMP levels in summer in the southeastern region, including Busan.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.24 no.2
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• pp.57-69
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• 2021

Urban green spaces supply ecosystem services (ESs), which are consumed by city residents and generate demand, to improve air quality. It is important to determine supply and demand for ESs and reduce the gap for efficient management. This study proposed a method to use the concept of supply and demand for ESs in the decision-making process for urban planning or management. PM₁₀ concentrations were converted to weight for demand assessment on PM₁₀ reduction, and PM₁₀ absorption capacity of all green spaces including the forests, and that of urban green spaces excluding forests, was calculated for each supply assessment. The differences in the calculated supply and demand were analyzed to derive the mismatched regions in Suwon. As a result, regions with big forested areas showed sufficient supply, indicating that the degree of mismatch among administrative neighborhoods (dong) varied greatly depending on whether they had a forest. An analysis of only urban green spaces showed that all neighborhoods lacked supply. Forests with high PM₁₀ absorption capacity had a great effect, but urban green spaces can be considered a key element in reducing PM₁₀ in daily life. Considering the mismatch of supply and demand, spatial distribution, and population distribution, it is possible to prioritize the supply of urban green spaces to reduce PM₁₀ and, furthermore, support decision making for priority zones subject to forest conservation and designation and cancellation of green spaces, which gives significance to this study.

• The Korea Journal of Herbology
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• v.38 no.4
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• pp.45-52
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• 2023

Objectives : Fine dust caused by environmental pollution cause oxidative damage and skin aging. In this study, The possibility of using the Codium fragile extract (CFE) as an anti-aging product for skin improvement was evaluated by confirming the protective effect of skin cells from PM10 (particulate matter 10) through inhibition of ROS and MMPs. Methods : In this study, elastase and collagenase inhibitory activities were evaluated. Cell viability was evaluated by treating keratinocytes (HaCaT cell line) with CFE at various concentrations. The cytoprotective effect from PM10 in keratinocyteswas evaluated using the 3-[4,5-dimethylthiazol]-2-yl]-2,5-diphenyl-tetrazoliumbromide (MTT) assay. ROS (reactive oxygen species) was measured in keratinocytes damaged by PM10 using DCF-DA (2′,7′-dichlorofluorescin diacetate) fluorescence staining. As an anti-aging effect of CFE, MMP-1 (matrix metalloproteinase-1) and MMP-1 (matrix metalloproteinase-9) inhibitory activities were evaluated. Results : As a result, CFE decreased the activity of elastase and collagenase. As a result of evaluating the toxicity of CFE, it is non-toxic at a concentration of 10 to 80 ㎍/㎖. Although cell viability of HaCaT cells treated with PM10 decreased, cell viability increased by 38% when treated with CFE 80 ㎍/㎖. Also, ROS decreased by 8.4%, and MMP-1 and MMP-9 decreased at CFE 80 ㎍/㎖. Conclusions : CFE showed excellent cell protection effect, and it is considered that it can be used in anti-aging products for skin improvement by effectively inhibiting ROS and MMPs from keratinocyte damage caused by fine dust.

• Journal of Preventive Medicine and Public Health
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• v.57 no.2
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• pp.108-119
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• 2024

Objectives: Abrupt changes in air pollution levels associated with the coronavirus disease 2019 (COVID-19) outbreak present a unique opportunity to evaluate the effects of air pollution on influenza risk, at a time when emission sources were less active and personal hygiene practices were more rigorous. Methods: This time-series study examined the relationship between influenza cases (n=22 874) and air pollutant concentrations from 2018 to 2021, comparing the timeframes before and during the COVID-19 pandemic in and around Thailand's Khon Kaen province. Poisson generalized additive modeling was employed to estimate the relative risk of hospitalization for influenza associated with air pollutant levels. Results: Before the COVID-19 outbreak, both the average daily number of influenza hospitalizations and particulate matter with an aerodynamic diameter of 2.5 ㎛ or less (PM_2.5) concentration exceeded those later observed during the pandemic (p<0.001). In single-pollutant models, a 10 ㎍/m³ increase in PM_2.5 before COVID-19 was significantly associated with increased influenza risk upon exposure to cumulative-day lags, specifically lags 0-5 and 0-6 (p<0.01). After adjustment for co-pollutants, PM_2.5 demonstrated the strongest effects at lags 0 and 4, with elevated risk found across all cumulative-day lags (0-1, 0-2, 0-3, 0-4, 0-5, and 0-6) and significantly greater risk in the winter and summer at lag 0-5 (p<0.01). However, the PM_2.5 level was not significantly associated with influenza risk during the COVID-19 outbreak. Conclusions: Lockdown measures implemented during the COVID-19 pandemic could mitigate the risk of PM_2.5-induced influenza. Effective regulatory actions in the context of COVID-19 may decrease PM_2.5 emissions and improve hygiene practices, thereby reducing influenza hospitalizations.

• Toxicological Research
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• v.27 no.3
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• pp.161-166
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• 2011

Carbon black, a particulate form of pure elemental carbon, is an industrial chemical with the high potential of occupational exposure. Although the relationship between exposure to particulate matters (PM) and cardiovascular diseases is well established, the cardiovascular risk of carbon black has not been characterized clearly. In this study, the cytotoxicity of carbon black to vascular smooth muscle and endothelial cells were examined to investigate the potential vascular toxicity of carbon black. Carbon black with distinct particle size, N330 (primary size, 28~36 nm) and N990 (250~350 nm) were treated to A-10, rat aortic smooth muscle cells and human umbilical vein endothelial cell line, ECV304, and cell viability was assessed by lactate dehydrogenase (LDH) leakage assay. Treatment of carbon black N990 resulted in the significant reduction of viability in A-10 cells at 100 ${\mu}g$/ml, the highest concentration tested, while N330 failed to cause cell death. Cytotoxicity to ECV304 cells was induced only by N330 at higher concentration, 200 ${\mu}g$/ml, suggesting that ECV304 cells were relatively resistant to carbon black. Treatment of 100 ${\mu}g$/ml N990 led to the elevation of reactive oxygen species (ROS) detected by dichlorodihydrofluorescein (DCF) in A-10 cells. Pretreatment of antioxidants, N-acetylcysteine (NAC) and sulforaphane restored decreased viability of N990-treated A-10 cells, and N-acetylcysteine, but not sulforaphane, attenuated N990-induced ROS generation in A-10 cells. Taken together, present study shows that carbon black is cytotoxic to vascular cells, and the generation of reactive oxygen contributes to the development of cytotoxicity. ROS scavenging antioxidant could be a potential strategy to attenuate the toxicity induced by carbon black exposure.

• Journal of the Korean Society for Marine Environment & Energy
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• v.9 no.4
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• pp.203-215
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• 2006

Field observations on the spatio-temporal distribution of organic matter of the surface sediment were carried out at 15 stations in the central parts of the South Sea of Korea from April 2002 to January 2003. The range of water temperature and salinity in bottom waters, mud content and water content of surface sediment were $8.06{\sim}23.35^{\circ}C,\;29.20{\sim}34.51\;psu,\;71.2{\sim}99.9%$ and $38.7{\sim}68.9%$, respectively. Measured parameters on the surface sediments of ignition loss (IL), chemical oxygen demand (CODs), phaeopigment, particulate organic carbon (POC) and particulate organic nitrogen (PON) also ranged in $3.9{\sim}l2.5%,\;9.60{\sim}44.05\;mgO_2/g-dry,\;1.58{\sim}29.51\;{\mu}g/g-dry,\;3.12{\sim}13.01\;mgC/g-dry$ and $0.49{\sim}2.00\;mgN/g-dry$, respectively. The spatio-temporal distribution of organic matter demonstrated higher concentrations offshore than at lesions near the coastal line. Higher concentrations occurred in the summer and spring. The results indicated that the origin of organic matter in surface sediments in the central part of the South Sea was autochthonous rather than allocthonous because the organic matter had an average C/N ratio of 6.44 (${\pm}0.51$). However, the composition of autochthonous organic matter was mainly derived from detritus rather than living phytoplankton, which was Indicated by the results of the POC/phaeopigment ratio. A principal component analysis (PCA) indicated that 73.2% of the variability in the data was described by two factors: 1) an 'environmental factor concerning the accumulation of materials (57.3%)' and 2) 'origin of organic matter and the composition by primary production (15.9%)'. The sedimentary environment in the central part of the South Sea was divided into four regions from the factor score of the PCA by the concentrations of organic matter and the composition ratio of organic matters from phytoplankton in surface sediments.

• Tuberculosis and Respiratory Diseases
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• v.60 no.4
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• pp.426-436
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• 2006

Background : Particulate matters (PM) when inhaled is known to induce pulmonary diseases including asthma and chronic bronchitis when inhaled. Despite the epidemiological proofevidence, the pathogenesis of PM-related pulmonary diseases is unclearremain poorly understood. Methods : Primary alveolar macrophages were harvested from the SPF and inflammatory rats by bronchioalveolar lavage (BAL). The cultured primary alveolar macrophages were treated with the medium only, PM only ($5{\sim}40{\mu}g/cm^2$), LPS (5ng/ml) only, and PM with LPS for 24 and 48 hours. The level of secreted nitric oxide (NO) was assayed from the cultured medium by using the Griess reaction. The cultured cells were utilized for the western blotting against the inducible nitric oxide synthase (iNOS) proteins. Immunocyto- chemical staining against the iNOS and NT-proteins were performed in cells that cultured in the $Lab-Tek^{(R)}$ chamber slide after treatments. Results : The PM that utilizein this experiments induced NO formation with iNOS expression in the cultured SPF and inflammatory rats alveolar macrophages, by itself. When the cells were co-treated with PM and LPS, there was a statistically significant synergistic effect on NO formation and iNOS expression over the LPS effect. The cells from the sham control showed minimal immunoreactivity for the NT-proteins. Significantly higher quantities of NT-proteins were detected in the PM and PM with LPS co-treated cells than from the sham control. Conclusion : Increased iNOS expression and NO formation with increased NT-proteins formation might be involved in the pathogenesis of PM-induced lung injury.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.8 no.4
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• pp.13-18
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• 1999

Recently among after-treatment devices which have high possibility of utility diesel oxidation catalyst(DOC) is concerned over the world. DOC oxidizes pollutants by means of activate-reaction during by-passing in the catalyst in doing so conversion efficiency of PM, CO and HC is high and this device does not have an effect on engine performance because back pressure is not nearly increased, But as a small amount of sulfur content in fuel is oxidized it makes sulfate which is absorbed on the surface of catalyst. So in this study the experiment is carried out by means of using ordinary fuel(0.1wt%) and low sulfur fuel(0.05wt%) with DOC and the emission gas of diesel engine is measured.