• 한국대기환경학회지
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• 제24권3호
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• pp.357-366
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• 2008

In this study, the analytical performance of trimethylamine (TMA) were investigated with respect to headspace-solid phase microextraction (HS-SPME) method. In order to induce the elution of aqueous TMA to headspace, NaOH was added as a decomposition reagent to aqueous TMA standard. By controlling the combination of three major variables for TMA extraction, the extent of extraction was compared between the two contrasting conditions for each variable (i.e., reaction time (long (L) vs short (S)), exposure temperature (30 vs $50^{\circ}C$), and exposure time (10 vs 30 min)). The results of this comparative analysis showed that the extraction efficiency for all eight types of HS-SPME combinations decreased on the order: L-30-30>L-50-10>L-30-10>L-50-30>S-30-30>S-50-30>S-50-10>S-30-10. The effect of reaction time appeared to exert significant influences on the relative recovery rate of HS-SPME at 90% confidence level. However, the effects of exposure temperature or exposure time were not so significant as reaction time. When the recovery rate of HS-SPME is compared against the direct injection of liquid standard into GC injector, it recorded as 2%. According to this comparative study, the reaction conditions for HS-SPME application can exert significant influences on the analysis of TMA.

• 한국산업보건학회지
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• 제10권2호
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• pp.140-149
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• 2000

In industrial field, there are several operations where a horizontal unidirectional airflow is used to control airborne contaminants. When a worker is immersed in a uniform freestream, a recirculating airflow can be created downstream of the worker by the phenomenon of boundary layer seperation. If the contaminant source and the breathing zone are within this near-wake region, high exposure may occur. The investigation for the effect of contaminant source location on worker exposure was performed by using CFD(Computational Fluid Dynamics). The airflow field was numerically calculated by assuming a steady flow and using the standard $k-{\varepsilon}$ turbulence model. As the results were compared with experimental data, the applicability of CFD was successfully verified. Subsequently, the breathing zone concentrations of the worker were predicted and compared with experimental data. The effects of contaminant density and turbulence intensity of freestream on worker exposure were evaluated.

• Safety and Health at Work
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• 제3권3호
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• pp.235-240
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• 2012

The objectives are to compare the airborne asbestos concentrations resulted from mitering of abestos cement roof sheets by a high-speed motor and a hand saw, and to monitor whether other workers near the test sites are vulnerable to the fibers exceeding the occupational exposure limit. Four test cases were carried out and altogether 7 personal and 4 area air samples were collected. The NIOSH method 7400 was employed for the air samplings and analysis. Using the phase contrast microscopy, fiber counting was conducted under Rule A. The study showed that the fiber concentration medians for personal air samples gathered from the two tools were 4.11 fibers/cc (ranged: 1.33-12.41 fibers/cc) and 0.13 fibers/cc (ranged: 0.01-5.00 fibers/cc) respectively. The median for the area samples was 0.59 fibers/cc (ranged: 0.14-3.32 fibers/cc). Comparing each study case, the concentration level caused by the high-speed motor saw was more than twice that of the hand saw. According to the area samples, the workers nearby the test site are at risk from high exposure to asbestos.

• Safety and Health at Work
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• 제13권1호
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• pp.9-16
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• 2022

Background: The global shift toward greener societies demands new technologies and work operations in the waste-management sector. However, progressive industrial methods do not necessarily consider workers' health. This study characterized workers' exposure to bioaerosols and investigated the bioaerosols' potential to engage the immune system in vitro. Methods: Full shift personal aerosol sampling was conducted over three consecutive days. Dust load was analyzed by gravimetry, fungal and actinobacterial spores were analyzed by scanning electron microscopy, and endotoxin by limulus amebocyte lysate (LAL) assay. In vitro exposure of HEK cells to airborne dust samples was used to investigate the potential of inducing an inflammatory reaction. Results: The total dust exposure level exceeded the recommended occupational exposure limit (OEL) of 5.0 mg/m³ in 3 out of 15 samples. The inhalable endotoxin level exceeded the recommended exposure level by a 7-fold, whereas the fungal spore level exceeded the recommended exposure level by an 11-fold. Actinobacterial spores were identified in 8 out of 14 samples. In vitro experiments revealed significant TLR2 activation in 9 out of 14 samples vs. significant TLR4 activation in all samples. Conclusion: The present study showed that the dust samples contained potentially health-impairing endotoxin, fungi, and actinobacterial levels. Furthermore, the sampled dust contained microbial components capable of inducing TLR activation and thus have the potential to evoke an inflammatory response in exposed individuals.

• Safety and Health at Work
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• 제15권1호
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• pp.96-101
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• 2024

Background: Silicosis among workers who fabricate engineered stone products in micro or small-sized enterprises (MSEs) was reported from several countries. Workplace exposure data of these workers at high risk of exposure to respirable crystalline silica (RCS) dust are limited. Methods: We surveyed workers performing cutting, shaping and polishing tasks at 6 engineered stone fabricating MSEs in Sydney, Australia prior to regulatory intervention. Personal exposure to airborne RCS dust in 34 workers was measured, work practices were observed using a checklist and worker demography recorded. Results: Personal respirable dust measurements showed exposures above the Australian workplace exposure standard (WES) of 0.1 mg/m³ TWA-8 hours for RCS in 85% of workers who performed dry tasks and amongst 71% using water-fed tools. Dust exposure controls were inadequate with ineffective ventilation and inappropriate respiratory protection. All 34 workers sampled were identified as overseas-born migrants, mostly from three linguistic groups. Conclusions: Workplace exposure data from this survey showed that workers in engineered stone fabricating MSEs were exposed to RCS dust levels which may be associated with a high risk of developing silicosis. The survey findings were useful to inform a comprehensive regulatory intervention program involving diverse hazard communication tools and enforcing improved exposure controls. We conclude that modest occupational hygiene surveys in MSEs, with attention to workers' demographic factors can influence the effectiveness of intervention programs. Occupational health practitioners should address these potential determinants of hazardous exposures in their workplace surveys to prevent illness such as silicosis in vulnerable workers.

• 한국산업보건학회지
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• 제3권1호
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• pp.68-77
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• 1993

To evaluate efficiencies of the local exhaust systems installed in chromiun and nickel eletroplating tanks, specifications of each tank and general performances of the local exhaust systems were measured in 16 electroplating plants from July 3 to November 24, 1992. Airborne concentrations of total chromium, hexa-chromium and nickel were also measured, Most of the local exhaust systems installed in electroplating plants were inadequately designed. Average capture velocities of local exhaust systems in chromium and nickel tanks were 0.45 m/sec and 0.29 m/sec. Average slot velocities in chromium and nickel tanks were 7.30 m/sec and 2.87 m/sec repectively. Both average capture and solt velocities were in noncompliance with the standards recommened by American Conference of Governmental Industrial Hygienists (ACGIH) and National Institute for Occupational Safety and Health (NIOSH), Exhausted air volume was insufficient in all local exhaust systems surveyed. Worker exposure levels to total chromium, hexa-chromium and nickel were $43.0{\mu}g/m^3$, $1.7{\mu}g/m^3$ and $9.3{\mu}g/m^3$, which were below the Korean Standard and U.S. Occupational Health and Safety Administration (OHSA) Permissible Exposure Limit(REL). However, Worker exposure level to hexa-chromium exceeded the NIOSH Recommended Exposure Limit(REL) of $1{\mu}g/m^3$. As the result of Scheffee's multiple comparions, worker exposure levels to all metals were significantly different between two groups by the management state of existing local exhaust systems (p<0.05). However, Difference between a group with local exhaust systems which were poorly managed and another group without local exhaust system was satatistically non-significant.

• 한국산업보건학회지
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• 제19권4호
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• pp.321-327
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• 2009

1,3-butadiene is classified as suspected human carcinogen, group A2(American Conference of Governmental Industrial Hygienists, ACGIH). In Korea, 1,3-butadiene has been used as a raw material; monomer, homopolymer, polybutadiene latex, acrylonitrile-butadiene-styrene(ABS) and styrene-butadiene rubber(SBR), in the petrochemistry and precision chemistry industry. As petrochemistry industry in Korea has been developed, the potential exposure possibility of 1,3-butadiene to workers can be increased. Therefore the purpose of this study is to evaluate airborne 1,3-butadiene concentration and workers' exposure levels in the workplace using 1,3-butadiene. Air samples were collected with 4-tert-butyl catechol(TBC) charcoal tube(100 mg/50 mg) and were analyzed by gas chromatograph/flame ionization detector(GC/FID) according to the Choi's method(2002). Geometric mean (GM) and arithmetic mean (AM) of total 59 workers' exposure concentrations to airborne 1.3-butadiene were 0.042 ppm and 1.51 ppm, respectively. Although most samples were lower than 1ppm, 2 samples(21.5ppm and 33.1ppm as 8hr-TWA) were exceeded the Korean standard(2ppm) over 10 times at the repair process in synthetic rubber and resin manufacture industry. 14 samples(41%) of total 34 short-term air samples were exceeded the Korean standard(10ppm as STEL) of Ministry Labor. 1,3-butadiene concentration(GM) in the synthetic rubber and resin manufacture industry(7.87ppm) was significantly higher than that in the monomer manufacure industry (0.35ppm)(p<0.05). Also in the sampling and repair process, each GM(range) was 1.39ppm(N.D.-469.6ppm) and 7.85ppm(N.D.-410.2ppm). In conclusion, it depends on the industry and process, 1,3-butadiene can be exposed to workers as high concentration for short-term.

• 한국산업보건학회지
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• 제17권3호
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• pp.245-253
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• 2007

This research was performed to evaluate the airborne personal concentration of hazardouse materials during the process of ship construction and surveyed from May 23 to June 30, 2007 in Kyungnam West Distirct, Korea. The subject was 94 ship construction workers exposed to welding fume and respirable particulate. The airborne concentrations of those were compared to Permissible Exposure Limit(PEL) from the Ministry of Labor in Korea. The airborne concentration of 23 samples(48.9%) of welding fumes was less than $5mg/m^3$, that of 16 (34.0%) was between 5 and $10mg/m^3$, and that of 8 (17.0%) was greater than $10mg/m^3$. The airborne concentration of 27 (57.4%) of respirable particulate masses was less than $5mg/m^3$ and the othere are greater than $5mg/m^3$. The welding fumes were identified containing the heavy metasl such as Fe, Mn, Zn, Mg, Ca, and Cu. The respirable particulates has similiar tendency with welding fumes in the component of heavy metals. But the concentration of Ca, Cu, Cr, and Ni turned out to be higher in welding fumes. Twenty (42.6%) of the 47 samples of welding fumes were exceeded PEL. In the heavy metals in welding fumes, ten (21.3%) of the 47 samples of Mn were exceeded PEL. Based on the results, the higher airborne hazardous materials were still exposed to wokers in ship construction process. It is suggested that the appropriate engineering control be applied to minimize the exposed cocnetration in ship building processes.

• 실내환경 및 냄새 학회지
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• 제17권4호
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• pp.355-361
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• 2018

Mold grows more easily when humidity is higher in indoor spaces, and as such is found more often on wetted areas in housing such as walls, toilets, kitchens, and poorly managed spaces. However, there have been few studies that have specifically assessed the level of mold in the indoor spaces of water-damaged housing in the Republic of Korea. We investigated the levels of airborne mold according to the characteristics of water damage types and explored the correlation between the distribution of mold genera and the characteristics of households. Samplings were performed from January 2016 to June 2018 in 97 housing units with water leakage or condensation, or a history of flooding, and in 61 general housing units in the metropolitan and Busan area, respectively. Airborne mold was collected on MEA (Malt extract agar) at flow rate of 100 L/min for 1 min. After collection, the samples were incubated at $25^{\circ}C$ for 120 hours. The cultured samples were counted and corrected using a positive hole conversion table. The samples were then analyzed by single colony culture, DNA extraction, gene amplification, and sequencing. By type of housing, concentrations of airborne mold were highest in flooded housing, followed by water-leaked or highly condensed housings, and then general housing. In more than 50% of water-damaged housing, the level of airborne mold exceeded the guideline of Korea's Ministry of Environment ($500CFU/m^3$). Of particular concern was the fact that the I/O ratio of water-damaged housing was greater than 1, which could indicate that mold damage may occur indoors. The distribution patterns of the fungal species were as follows: Penicillium spp., Cladosporium spp. (14%), Aspergillus spp. (13%) and Alternaria spp. (3%), but significant differences of their levels in indoor spaces were not found. Our findings indicate that high levels of mold damage were found in housing with water damage, and Aspergillus flavus and Penicillium brevicompactum were more dominant in housing with high water activity. Comprehensive management of flooded or water-damaged housing is necessary to reduce fungal exposure.

• 한국재난정보학회 논문집
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• 제19권2호
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• pp.344-351
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• 2023

연구목적: 본 연구는 미생물의 비열 멸균 기술로서 실내 공간 내 유전체 장벽 방전 플라즈마 모듈의 방전시간에 따른 오존 발생 농도변화의 값을 통한 실내 공간 내 부유세균 살균 성능을 분석하였다. 연구방법: 76m³체적 공간의 공조장치의 공기배출 부분에 DBD 플라즈마 모듈을 설치하고 2m 떨어진 거리에서 DBD 플라즈마 처리 시간에 따라 공기 시료를 포집하여 미처리 대조군과 비교하여 부유세균 저감 효과를 분석하였다. 또한 DBD 플라즈마 방전에 따른 오존발생농도를 확인하였다. 연구결과: 대조군의 총 세균수는 1.83~2.00 logCFU/m³의 결과가 나왔으며, 시험군이 대조군에 비해 실내공기 중 부유세균의 최소 92.057%에서 최대 99.999%의 저감 효과를 보였다. 또한 평균 오존발생농도 0.04ppm으로 오존 발생농도 기준인 0.05ppm보다 낮은 결과를 확인하였다. 결론: 인체에 무해한 오존량과 DBD방전 플라즈마량을 조절함으로써 공기 중 부유세균, 바이러스등의 감염병 전파 방지의 수단으로 플라즈마 방전을 사용함에 기준이 될 것으로 사료된다.