• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.27 no.4
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• pp.283-290
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• 2017

Objectives: This study aimed to evaluate the relationship between filter replacement and filter performance change in particulate filters used in the workplace. Methods: Three types of particulate respirator filters are mainly used in the workplaces. These were tested against the filter performance safety certification standard for dust masks established by the Ministry of Employment and Labor(MoEL). Used filters were collected to test their performance, such as filter pressure drop, efficiency, and quality factors. All these factors were evaluated by a filter tester. To compare filter performance between used and new ones, the same kinds of new filters were also tested together under the same procedures. Results: A total of 270 used filters were collected for testing. The main reasons to replace the filters were difficulty in breathing(46.2%), dirty/odor influx(19.7%), and a combination of factors(26.7%). The pressure drop for two special class groups was significantly different(new filters: $20.72{\pm}3.33mmH_2O$; used filters: $24.70{\pm}5.26mmH_2O$, p<0.0001). In the case of penetration, new filter groups indicated $0.0032{\pm}0.0040%$, while that of the used filters was $0.0596{\pm}0.1187%$. The quality factor for the used filters($0.34{\pm}0.09$) significantly decreased compared to the new filters($0.53{\pm}0.08$) (p<0.0001). Conclusions: Filter performance including pressure drop, penetration, and the quality factor was evaluated and compared between new and used filters in the workplace. The results showed that general filter performance deteriorated more for change of pressure drop, penetration and the quality factor.

• Journal of Environmental Health Sciences
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• v.43 no.5
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• pp.431-437
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• 2017

Objectives: To protect the health and safety of residents during chemical accidents, the governmental authorities need to provide personal protective equipment (PPE) to citizens who desire it. This study aims to investigate residents'awareness of PPE and perform an economic analysis on providing PPE to residents near chemical plants prior to the establishment of a related law. Methods: This study was carried out through a questionnaire completed by 600 residents composed of items such as residents'awareness of PPE, what type of PPE they need, and how to purchase PPE. Economic analysis (cost-benefit analysis) was conducted on providing PPE to residents near chemical plants on basis of the Gumi City hydrogen fluoride accident of 2012. Results: The results of the questionnaire showed that most residents recognized the need for PPE preparedness for chemical accidents, in particular, for respirators. The level of expense that respondents were prepared to shoulder to share the burden was $25. Except for chemicals of hazard level 2, the benefit of all kinds of chemical accident preparedness considerably exceeded costs in the cost-benefit analysis on providing PPE. An estimated government budget of $20 million per year would be required to provide PPE (hood-type mask) for all residents within a one-kilometer radius of chemical plants in Korea, but only $5.8 million when residents share the expenses. Conclusion: The results of this study suggest that programs for providing PPE for residents near chemical plants should be established by law.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.12
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• pp.820-824
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• 2008

Electret filter media are used in general ventilation filters, disposable respirators, vehicle cabin filters, vacuum cleaners and room air cleaners. There are basic mechanisms of interception, inertial impaction, diffusion, gravitational settling, electrostatic attraction by which an aerosol particle can be deposited onto a fiber in a filter. The ability of fine particle removal strongly depends on the electrostatic forces between particles and polarized fibers. Thus, the stability of the fiber polarization is a major factor in the reliability of electret filters. In this study, the electret filter is made by electrospinning process using Polystyrene which is dissolved by 5 : 5 of Tetrahydrofuran (THF) and Dimethylformamide (DMF). Also the electrical properties and the filtration performances of electrospun filter media are Quantitatively investigated. Electrical properties of electrospun filters have been studied on surface charge potential and surface charge density. Also the filtration performance of the electret filters are evaluated on collection efficiency. The surface charge potential and the surface charge density of electrospun PS filters are increased with increasing applied voltage and saturated at 30 kV of applied voltage. Also collection efficiency of electro spun filters is increased with increasing surface charge potential and surface charge density. But the surface charge potential is decreased by natural decay and it causes deterioration of particle collection efficiency.

• Journal of Sensor Science and Technology
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• v.24 no.5
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• pp.319-325
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• 2015

While the conventional personal protective equipments (PPEs) covers a variety of devices and garments such as respirators, turnout gear, gloves, blankets and gas masks, several electronic devices such as personal alert safety system (PASS) and heads-up displays in the facepiece have become a part of firefighters personal protective equipments through past several years. Furthermore, more advanced electronic sensors including location traking sensor, thermal imaging caerma, toxic gas detectors, and even physiological monitoring sensors are being integrated into ensemble elements for better protection of firefighters from fire sites. Despite any electronic equipment placed on the firefighter must withstand environmental extremes and continue to properly function under any thermal conditions that firefighters routinely face, there are no specific criteria for these electronics to define functionability of these devices under given thermal conditions. Although manufacturers provide the specifications and performance guidelines for their products, their operation guidelines hardly match the real thermal conditions. Present study overviews firefighter's fatalities and thermal conditions that firefighters and their equipments face. Lastly, thermal packaging methods that we have developed and tested are introduced.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.19 no.2
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• pp.102-112
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• 2009

The greatest concern of vapor/gas respirators is when to exchange chemical cartridges, but it is very difficult to estimate the breakthrough time of them in the workplace spot due to so many factors influencing on breakthrough. There needs to study on estimating cartridge exchange period available practically in the spot, even if it is not precise. In the previous study, authors suggested the method on estimating service-life of chemical cartridges using cartridges discarded after use. This followed study was to estimate exchange period for chemical cartridges using comparison of concentrations between Korean Occupational Exposure Limits (KOELs) and odor thresholds of chemicals. Chemicals were divided into four groups, I, II, III and IV groups. Group I chemicals are relatively safe if cartridges are just or slightly delayed exchanged when smelling since odor thresholds were less than 0.5 times KOELs. Odor threshold of Group II chemicals are 0.5~2.0 times KOELs and potentially hazardous if cartridges are exchanged when smelling. Those chemicals should be conducted program on estimating service-life of cartridges, which was just previously published (J Kor Soc Occup Environ Hyg 2008;18(3) 204-215). Group III chemicals (odor thresholds are more than 2.0 times KOELs) and Group IV chemicals (odorless or no data for smelling) must be performed the above mentioned program before cartridges. Even if this method on cartridge exchange using odor threshold is practically widely used in the workplace spot in the present, program on estimating service-life of cartridges is recommended for all chemicals to reduce potentially hazards.

• Journal of Preventive Medicine and Public Health
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• v.43 no.3
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• pp.274-278
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• 2010

Objectives: This report describes the results of an investigation on an outbreak of novel influenza A (H1N1) in an English language Institute in Seoul, Korea in May 2009. Methods: In this outbreak, novel influenza A (H1N1) was confirmed in 22 of 91 trainees, trainers and staff members. The trainees and 2 staff members were isolated in an assigned facility and the rest were isolated in their homes after we discovered the first patient with novel influenza A (H1N1). After the isolation, the people in the assigned facility were educated to use N95 respirators and they received oseltamivir for prophylaxis. Results: The initial findings in this study suggest that the symptoms were mild and similar to those of seasonal influenza. The classmates and roommates of the infected patients were more likely to get infected with novel influenza A (H1N1) than the trainees who were not classmates or roommates of the patients (OR: 3.19, 95% Cl=0.91 - 11.11 for classmates and OR: 40.0, 95% Cl=7.4-215.7 for roommates). Conclusions: The public health response seems successful in terms of preventing the spread of this virus into the local community.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.29 no.3
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• pp.336-342
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• 2019

Introduction: An unexpected death was reported in a beginner immediately after starting the work at a plating factory. After the incident, air sampling was performed using a simulation of the situation as it had been at the time. Methods: To evaluate the airborne concentration of hydrogen cyanide, a total of six samples were collected: one personal sample, three area samples, and two background samples (office and outdoors). Hydrogen cyanide measurement was performed according to the standard sampling protocol recommended by the U.S. NIOSH (National Institute of Occupational Safety and Health). Results: The highest concentration of hydrogen cyanide was 0.938 ppm measured in a sample collected from the plating bath area with local exhaust ventilation. This value was approximately 20% of the ceiling occupational exposure limit. The personal sample showed a concentration of 0.135 ppm. Samples collected near the bath in which the incident occurred and a dehydrator showed hydrogen cyanide concentrations of 0.236 ppm and 0.101 ppm, respectively. Hydrogen cyanide was not detected in the background samples (office and outdoors). Conclusions: It is necessary to use proper ventilation systems and respirators in plating factories to prevent acute poisoning. Furthermore, it is important to educate and train new workers dealing with toxic substances.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.32 no.2
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• pp.163-171
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• 2022

Objectives: Fit performance may vary depending on the ambient aerosol number and ratio in respective test environment. Although several instrument can measure it, they differ with respect to the measurement principle and the range of ambient aerosols collected to calculate the fit factor. Methods: In this study, the fit performance between a condensation nuclei counter(CNC) and an optical particle counter(OPC) was compared according to ambient aerosol number concentration, and evaluated consistency. One type respirators(N95 masks) was worn by 50 participants PortaCount®(Pro+ 8038) and MT®(05U) were connected with one probe to one mask, and Fit Factors(FFs) were measured simultaneously. Results: The interclass correlation coefficient of the fit factor and ambient aerosol number, as measured by the two instrument, was 0.82 and 0.79, respectively, indicating a high consistency level. On the other hand there was a significant correlation between the successful test performance of the OPC instrument and the ambient aerosol number. Conclusions: The test was passed with the CNC and OPC instruments when the ambient aerosol number was 635-3,332 particles/cm³ and 368-1,976 particles/cm³, respectively. Thus, the ideal ambient aerosol number of particles differed between the two instrument.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.20 no.3
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• pp.147-155
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• 2010

This study was conducted to investigate the benzene exposure levels in coal chemical and petrochemical refining industries during BTX turnaround (TA) processes where benzene was being produced. Three companies producing benzene were selected, one coal chemical and two petrochemical industries. TA processes were classified into three stages: shut down, maintenance, and start up. Data was analyzed by classifying the refining method into 2 groups (Petrochemistry, Coal chemistry) for 823 workers. Comparing the data from petrochemical industries with data from a coal chemical refining industry, while benzene concentration levels of long-term samples during TA were not statistically different (p> 0.05), those levels of short-term samples were significantly different (p< 0.001). About 4.79 % of data in petrochemical industries exceed the occupational exposure limits (OELs) of benzene, 1 ppm. In a coal refining methods, about 15.7% exceeded the benzene OELs. The benzene concentrations in maintenance and start up stage of TA for petrochemical refineries were higher than those in a coal chemical refinery (p <0.01). These findings suggest that the coal chemical refining site requires more stringent work practice controls compare to petrochemical refining sites during TA processes. Personal protective equipments including organic respirators should be used by TA workers to protect them from benzene overexposure.

• Journal of Environmental Health Sciences
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• v.42 no.6
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• pp.430-437
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• 2016

Objectives: The new Chemical Control Act from the Korean Ministry of Environment (2014-259) simply states only in basic phrases that every worker handling the listed chemicals should wear personal protective equipment (PPE) and does not consider the different hazard characteristics of particular chemicals or work types. The purpose of this study was to produce an exposure risk matrix and assign PPE to the categories of this matrix, which would be useful for revising the act to suggest PPE to suit work types or situations. Methods: An exposure risk matrix was made using hazard ranks of chemicals and workplace exposure risks in the previous study. For the 20 categories of exposure risk matrix PPE, levels A, B, C, D as classified by OSHA/EPA were assigned. After 69 hazardous chemicals were divided into 11 groups according to their physiochemical characteristics, respirators, chemical protective clothing (CPC), gloves and footwear were suggested on the basis of the assigned PPE levels. Results: PPE table sheets for the 11 groups were made on the basis of work types or situations. Full facepiece or half-mask for level C was recommended in accordance with the exposure risk matrix. Level A was, in particular, recommended for loading or unloading work. Level A PPE should be worn in an emergency involving hydrogen fluoride because of the number of recent related accidents in Korea. Conclusion: PPE assignment according to the exposure risk matrix made by chemical hazards and work type or situation was suggested for the first time. Each type of PPE was recommended for the grouped chemicals. The research will be usefully used for the revision of the Chemical Control Act in Korea.