• Journal of Environmental Health Sciences
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• v.36 no.3
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• pp.191-198
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• 2010

The aim of this study was to determine the concentrations of air-borne microorganisms (bacteria, fungi, gram negative bacteria (GNB), endotoxins, and respirable suspended particles (RSPs), and their correlation with environmental parameters (temperature, humidity, and carbon dioxide levels) in duck houses. The mean concentrations of bacteria, fungi, and GNB were very high (> $10^6\;CFU/m^3$), and endotoxin levels exceeded $10^3\;EU/m^3$. Among the various work stages, in the task of receiving ducks, bacteria were $6.2{\times}10^6;CFU/m^3$, and GNB were $5.4{\times}10^6\;CFU/m^3$, while RSPs levels were $397.6\;{\mu}g/m^3$ and endotoxin levels were $47.2{\times}10^3\;EU/m^3$ in the task of dividing the ducks, and fungi were $4.9{\times}10^6\;CFU/m^3$ in the task of shipping the ducks. The concentrations of RSPs and endotoxins were significantly higher in tasks involving greater movement of ducks in the house, relative to tasks involving little movement of ducks (p<0.05). Further, with progression in growth of the ducks, the concentrations of bacteria, GNB, endotoxins, and RSPs were significantly increased. There was significant correlation between levels of GNB with bacteria (r=0.75) and fungi (r=0.86), endotoxins with RSPs (r=0.75), bacteria with fungi (r=0.39), and carbon dioxide with RSPs (r=0.38), bacteria (r=0.33), and endotoxins (r=0.31). These results suggest considerable respiratory hazard for farmers in these environments.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.30 no.2
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• pp.109-123
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• 2020

Objectives: The aims of this study were to review the standards and key components of the standards for disposable masks in Korea, the US, EU, Japan, and China and to evaluate the appropriateness of disposable masks during a virus pandemic. Methods: We reviewed the standards in the above countries and compared their key elements for each standard. For the second purpose, systemic paper gathering using key words like 'mask', 'respirator' 'virus', and 'coronavirus' in the PubMed search engine was performed. Fifty-three papers were selected and reviewed in regard to the appropriateness of test protocols with sodium chloride(NaCl) particles for virus filtration and the effectiveness against viruses. Results: The standards for masks are largely divided into two categories: US standards and EU standards. In Korea, the Ministry of Employment and Labor adapted the EU standards for workers and the Health Masks adopted the Ministry of Employment and Labor standards by the Ministry of Food and Drug Safety. Regarding airborne viral infections, WHO emphasizes only droplet infection, while many studies have shown that small particles enter the air through coughing or sneezing, which increases the possibility of airborne infection. Compared to other particles, various factors such as airborne viability and the ability to replicate the virus in the body are further involved in the virus's airborne infection rate. Airborne infection is classified into absolute air infection, preferential air infection, and opportunistic air infection. The NaCl-certified N95 mask showed good filtration efficiency against viruses and NaCl particles were proved to be a surrogate material for viruses. From this, KF94 is also expected to be effective in blocking viruses. Conclusion: The N95 test method could be used as a surrogate test method for virus filtration. N95-class masks have been found to effectively block viral infections in the air. However, surgical or medical masks are only partially effective against airborne virus infection though they could effectively block large droplet infection. However, most studies considered in this study targeted N95 in foreign countries and studies on masks actually used in Korea are very limited, so studies on microorganisms and reuse on domestic masks should be conducted in the future.

• Korean Journal of Microbiology
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• v.43 no.3
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• pp.193-200
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• 2007

Indoor airborne bacterial and fungal concentrations were examined at classrooms and corridors of 3 elementary schools in Ulsan. Airborne microorganisms were collected with an impaction-type air sampler using plate count agar and dichloran rose bengal chloramphenicol agar. During the semester, concentrations of bacteria ranged $168{\sim}3,887 MPN/m^3$ at classrooms and $168{\sim}6,339 MPN/m^3$ at corridors, while those of fungi ranged $34{\sim}389 MPN/m^3$ at classrooms and $91{\sim}507 MPN/m^3$ at corridors. The bacterial concentrations showed larger variations between situations and schools compared to those of fungi. When airborne bacteria were isolated and identified, 84% were observed as Gram-positive, and Micrococcus spp. was the most abundant group with 61% of tested isolates, followed by genus Staphylococcus with 10%. The Micrococcus spp. isolates, of which 75% were identified as M. luteus, appeared to be from human origins. The protective pigments and substantial cell wall of Micrococcus may provide selective advantage for their survival in the air. We also isolated and identified 15 genera of filamentous fungi. The most common culturable fungi were Cladosporium, Aspergillus and Penicillium, and these 3 genera were 69% of fungal isolates. Genus Stachybotrys, of which S. chartarum is a well known producer of many potent mycotoxins, was also detected from one of the schools. further systematic studies are necessary with an emphasis on species identification and mycotoxin production of isolated fungal genera, including Aspergillus, Penicillium, and Stachybotrys.

• Journal of Environmental Health Sciences
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• v.19 no.1
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• pp.30-36
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• 1993

A survey was conducted to measure concentration of airborne microbe in a hospital using RSC air sampler during October~November 1991.The result was as follows: 1) In an agar strip GK-A media for total counts of microbial particles. The highest count were 1384 CFU/m$^3$ in the main lobby, followed by 912 CFU/m$^3$, in the obstetric room, 688 CFU/m$^3$ in 1CU. By gram staining, the distribution for organisms in the air were shown 74.1% in gram possitive cocci followed by 16.8%, in gram possitive bacilli 6.7% in gram negative bacilli and 4.7% in yeast, but low organism was detected in recovery room with 194 CFU/m$^3$. 2) In agar strip S media for Staphylococci the count at the main lobby was detected in the recovery room with 92 CFU/m$^3$, Tests of coagulase were negative Staphylococci with 78%, and positive Staphylococci with 22%. The Staphylococci were highly resistance to penicillin, ampicillin and sensitive to amikacin, cefazolin, gentamycin and chloramphenicol. 3) In agar strip C media for coliform bacteria the colony counts at the main lobby was 139 CFU/m$^3$ and treatment room was 190 CFU/m$^3$, most frequently isolated microorganisms were non fermentative bacilli. 4) In agar strip HS media for yeast and molds. Most frequently colony counts 17~76 CFU/m$^3$, 0.5% lactophenol cotton blue stains were shown unidentified 77.2%, 8.1%, in Penicillium 8.1% in Aspergillus, and 3.8% in mucor.

• Safety and Health at Work
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• v.1 no.2
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• pp.183-191
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• 2010

Objectives: The objective of this study is to investigate the distribution patterns and exposure concentrations of bioaerosols in industries suspected to have high levels of bioaerosol exposure. Methods: We selected 11 plants including 3 livestock feed plants (LF industry), 3 metal working fluids handling plants (MWFs industry), and 5 sawmills and measured total airborne bacteria, fungi, endotoxins, as well as dust. Airborne bacteria and fungi were measured with one stage impactor, six stage cascade impactor, and gelatin filters. Endotoxins were measured with polycarbonate filters. Results: The geometric means (GM) of the airborne concentrations of bacteria, fungi, and endotoxins were 1,864, $2,252\;CFU/m^3$, and $31.5\;EU/m^3$, respectively at the sawmills, followed by the LF industry (535, $585\;CFU/m^3$, and $22.0\;EU/m^3$) and MWFs industry (258, $331\;CFU/m^3$, and $8.7\;EU/m^3$). These concentrations by industry type were significantly statistically different (p < 0.01). The ratio of indoor to outdoor concentration was 6.2, 1.9, 3.2, and 3.2 for bacteria, fungi, endotoxins, and dust in the LF industry, 5.0, 0.9, 2.3, and 12.5 in the MWFs industry, and 3.7, 4.1, 3.3, and 9.7 in sawmills. The respiratory fractions of bioaerosols were differentiated by bioaerosol types and industry types: the respiratory fraction of bacteria in the LF industry, MWF industry, and sawmills was 59.4%, 72.0%, and 57.7%, respectively, and that of fungi was 77.3%, 89.5%, and 83.7% in the same order. Conclusion: We found that bioaerosol concentration was the highest in sawmills, followed by LF industry facilities and MWFs industry facilities. The indoor/outdoor ratio of microorganisms was larger than 1 and respiratory fraction of microorganisms was more than 50% of the total microorganism concentrations which might penetrate respiratory tract easily. All these findings suggest that bioaerosol in the surveyed industries should be controlled to prevent worker respiratory diseases.

• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.4
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• pp.789-799
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• 1998

Literatures on microorganisms of traditional Korean nuruk published since 1945 were reviewed in this paper. Traditional Korean nuruk consists of raw barley and various grains. Traditional Korean nuruk consists of unbolied raw barely and various grains. They are ground to paste and moistened, and then naturally inoculated by airborne microorganisms. Therefore, many kinds of microorganisms such as fungi, yeast, and bacteria grwo in nuruk. Since 1945, new 14 species of Aspergillus and 9 species of Penicillium have been identified from traditional Korean nuruk. Total number of fungal species identified so far is now up to 38 species among 12 different genus. Among newly isolated fungal species, Aspergillus penicilloides and Penicillium, expansum showed not only high production rate of acid and amylase but also extreme stability of the enzyme at room temperature for 3 months. As examples of newly isolated yeast species, there are 5 species of Candida, 4 species of Hansenula, 1 species of Pichia and 1 species of Schizosaccharomyces. Total number of yeast species isolated so far is up to 18 species from different 8 genus. Newly isolated bacteria, were Bacillus pumilus, Lactobacillus casei and Leuconostoc mesenteroides.

• Korean Journal of Microbiology
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• v.39 no.4
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• pp.253-259
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• 2003

To assess microbiological indoor air quality in kindergartens, concentrations of viable airborne microorganisms were seasonally determined at three kindergartens in Ulsan from April, 2002 to January, 2003. Sampling was performed with an impaction-type air sampler and three different media. The numbers of bacteria grown on Staphylococcus medium were between 84 and 4,150 MPN/m3 with an average of 827 MPN/m3, and those on standard method agar ranged from 50 to 2,636 MPN/m3 with an average of 580 MPN/m3. The bacterial concentrations were highest in summer, followed by fall, spring, and winter, and were significantly correlated with indoor temperature. Among the colonies, 45.6~61.0% were observed as Gram-positive cocci and 8.5~20.6% were Gramnegative rods. Micrococcus species were the dominant organisms. The numbers of fungi ranged from 0 to 1,888 MPN/m3(661 MPN/m3 average) based on colony counts with dichloran rose bengal chloramphenicol agar. On average, the fungal concentrations were highest in summer and lowest in winter. Penicillium species and Aspergillus species were identified from the colonies. The obtained data can be utilized as a step to set a guideline for bioaerosols in indoor environment of schools.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.2
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• pp.1204-1210
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• 2014

New control methods are proposed for indoor air quality by removing fine airborne dust-particles. As suspended fine dust-particles contain inorganic dust as well as fine organic bacteria, studies for simultaneous control of these contaminants are required. In this study, photocatalytic disinfection of indoor suspended microorganisms such as E. coli and Bacillus subtilis is performed by three types of photocatalysts with UVA irradiation. The UVA irradiation strength was controlled to the minimum $3{\mu}W/cm^2$, and ZnO, $TiO_2$, and ZnO/Laponite ball were used as the catalysts. The results indicate that E. coli was removed over 80 % after about 2 hours of reaction with UVA and all three types of photocatalysts, whereas only with UVA, around 50 % E. coli removal was obtained. Among the catalysts, ZnO/Laponite composite ball was found to have similar sterilizing capacity to $TiO_2$. However, in case of B. subtilis, which has thick cell wall in its spore state, disinfection was not effective under the low UVA irradiation condition, even with the catalysts. Further studies need to figure out the optimal UVA irradiation ranges as well as photocatalysts doses to control airborne dust, to provide healthy clean air environment.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.1
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• pp.868-876
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• 2015

This study was conducted to measure the concentrations of total culturable bacteria (TCB) and to identify the bacteria in thirty public facilities (7 elderly-care facilities, 4 hypermarkets, 4 university hospitals, 7 child care facilities, 4 subway stations and 4 bus terminals) in Seoul and Gyeonggi-Do Province. Although all concentrations measured in these study facilities did not exceed the national maintenance standard, it is believed that elderly-, child-care facilities should be high priority facilities to improve the indoor air quality and it is important to study the health effects and the airborne bacteria concentration of public facilities including non-culturable bacteria or allergen.

• Korean Journal of Organic Agriculture
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• v.7 no.2
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• pp.99-106
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• 1999

In order to acquire microbial agents that can be utilized for biological control of bitter rot(Glomerella cingulata), the major airborne disease to apple, the effective microorganisms were isolated, tested for antagonistic activity to the pathogen. Through the screening of more than 1,000 species of microorganisms collected in nature, 11 species of antagonists were selected. On of the 11 species, one species designated as CH141 demonstrated outstanding activity. The bacterial strain, CH1141 exerted antagonistic efficiency of 65% on Glomerella cingulata. The CH1141 was identified as a bacterial strain to Bacillus subtilis based on morphology, culture conditions, and physiobiochemical characteristics.