• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.27 no.4
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• pp.313-323
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• 2017

Objectives: This study aimed to assess exposure to black carbon(BC) among forklift operators and to identify environmental and occupational factors influencing their BC exposure. Methods: We studied a total of 23 forklift operators from six workplaces manufacturing paper boxes. A daily BC exposure assessment was conducted during working hours from January to April 2017. A micro-aethalometer was used to monitor daily BC exposure, and information on work activities was also obtained through a time-activity diary(TAD) and interviews. BC exposure records were classified into four categories influencing BC exposure level: working environment, workplace, forklift operation, and job characteristics. Analysis of variance(ANOVA) was used to compare average BC exposure levels among the four categories and the relationships between potential factors and BC exposure were analyzed using a multiple linear regression model. Results: The operators' daily exposure was $12.9{\mu}g/m^3$(N=9,148, $GM=7.5{\mu}g/m^3$) with a range: $0.001-811.4{\mu}g/m^3$. The operators were exposed to significantly higher levels when they operate a forklift in a room ${\leq}20,000m^3$($AM=12.3{\mu}g/m^3$), in indoor workplaces($AM=16.3{\mu}g/m^3$), when they operate a forklift manufactured before 2006 ($AM=13.2{\mu}g/m^3$), a forklift with a loading limit of four-tons($AM=27.1{\mu}g/m^3$), with a roll and bale type clamp($AM=17.1{\mu}g/m^3$), and with no particulate filter($AM=15.7{\mu}g/m^3$). Conclusions: Occupational factors including temperature, smoking, season, daytime, room volume($m^3$), location of operating, and manufacturing era and model of forklift influenced the BC exposure of forklift operators. The results of this study can be used to minimize the BC exposure of forklift operators.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.20 no.3
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• pp.192-202
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• 2010

This study aimed to suggest the severity of indoor air pollutants in screen gold arenas which were not sufficiently investigated in Korea up to now and to help users to enjoy golf in more pleasant indoor environment. The indoor environment survey was conducted with 21 screen gold arenas in Seoul from Oct. 28, 2008 to March 13, 2009. Indoor air quality was measured and analyzed in accordance with the Air Pollution Process Test Method specified bu NIOSH(2005). The screen golf arenas are mostly in the underground floors in this study, 4 on the ground floors(19.0%) and 17 in the underground floors(81.0%). In the air in screen golf arenas, the geometric mean of benzene, toluene, ethylbenzene and xylene were 2.92 ${\mu}g/m^3$, 70.34 ${\mu}g/m^3$, 14.00${\mu}g/m^3$ and 31.43 ${\mu}g/m^3$, respectively, which exceeded the exposure limites. Each arena exceeded the exposure limit for one pollutant each. However, styrene didn't exceed the limit as 8.09 ${\mu}g/m^3$. Furthermore, the geometric mean of formaldehyde was 63.11${\mu}g/m^3$ and 7 arenas exceeded the limit. The geometric mean of volatile organic compounds(VOCs) was 428.41${\mu}g/m^3$ and 10 arenas exceeded the limit. For the density distribution of pollutants by location, benzene, toluene, ethylbenzene, xylene, styrene and formaldehyde showed higher density distribution in underground spaces, for which the statistically significant difference was not found. However, PM10 showed the statistically significant difference (p<0.05). In accordance with the analysis on the correlation between the density of pollutants in the screen golf arenas, Pearson correlation coefficient between ethylbenzene and styrene was 0.980, very significant correlation(p<0.01). The correlation coefficients between the density of toluene, ethylbenzene, xylene and styrene and that of VOCs were 0.543, 0.434, 0.451 and 0.459, respectively, which demonstrated the statistically significant difference (p<0.05).

• Nuclear Engineering and Technology
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• v.52 no.8
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• pp.1784-1791
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• 2020

The 14 MeV neutron generator facility is being developed by the Institute for Plasma Research India to conduct the lab scale experiments related to Indian breeding blanket system for ITER and DEMO. It will also be utilized for material testing, shielding experiments and development of fusion diagnostics. Occupational radiation exposure control is necessary for the all kind of nuclear facilities to get the operational licensing from governing authorities and nuclear regulatory bodies. In the same way, the radiation exposure for the 14 MeV neutron generator facility at the occupational worker area and accessible zones for general workers should be under the permissible limit of AERB India. The generator is designed for the yield of 10¹² n/s. The shielding assessment has been made to estimate the radiation dose during the operational time of the neutron generator. The facility has many utilities and constraints like ventilation ducts, accessible doors, accessibility of neutron generator components and to conduct the experiments which make the shielding assessment challenging to provide proper safety for occupational workers and the general public. The neutron and gamma dose rates have been estimated using the MCNP radiation transport code and ENDF -VII nuclear data libraries. The ICRP-74 fluence to dose conversion coefficients has been used for the assessment. The annual radiation exposure has been assessed by considering 500 h per year operational time. The provision of local shield near to neutron generator has been also evaluated to reduce the annual radiation doses. The comprehensive results of radiation shielding capability of neutron generator building and local shield design have been presented in the paper along with detailed maps of radiation field.

• Safety and Health at Work
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• v.2 no.3
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• pp.210-217
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• 2011

Objectives: The purpose of this study was to measure the concentration of volatile organic compound (VOC)s originated from the chemicals used and/or derived from the original parental chemicals in the photolithography processes of semiconductor manufacturing factories. Methods: A total of four photolithography processes in 4 Fabs at three different semiconductor manufacturing factories in Korea were selected for this study. This study investigated the types of chemicals used and generated during the photolithography process of each Fab, and the concentration levels of VOCs for each Fab. Results: A variety of organic compounds such as ketone, alcohol, and acetate compounds as well as aromatic compounds were used as solvents and developing agents in the processes. Also, the generation of by-products, such as toluene and phenol, was identified through a thermal decomposition experiment performed on a photoresist. The VOC concentration levels in the processes were lower than 5% of the threshold limit value (TLV)s. However, the air contaminated with chemical substances generated during the processes was re-circulated through the ventilation system, thereby affecting the airborne VOC concentrations in the photolithography processes. Conclusion: Tens of organic compounds were being used in the photolithography processes, though the types of chemical used varied with the factory. Also, by-products, such as aromatic compounds, could be generated during photoresist patterning by exposure to light. Although the airborne VOC concentrations resulting from the processes were lower than 5% of the TLVs, employees still could be exposed directly or indirectly to various types of VOCs.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.30 no.1
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• pp.1-9
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• 2020

Objectives: The purpose of this case study is to assess workers' exposure to carbon nanotubes(CNTs) and characterize particles aerosolized during the process of producing CNT-enabled polytetrafuoroethylene(PTFE) composites at a worksite in Korea. Methods: Personal breathing zone and area samples were collected for determining respirable concentrations of elemental carbon(EC) using NIOSH(National Institute for Occupational Safety and Health) Method 5040. Personal exposure to nano-sized particles was measured as the number concentration and mean diameter using personal ultrafine particle monitors. The number concentration by particle size was measured using optical particle sizers(OPS) and scanning mobility particle sizers(SMPS). Transmission electron microscopy (TEM) area samples were collected on TEM grids and analyzed to characterize the size, morphology, and chemistry of the particles. Results: Respirable EC concentrations ranged from 0.04 to 0.24 ㎍/㎥, which were below 23% of the exposure limit recommended by NIOSH and lower than background concentrations. Number concentrations by particle size measured using OPS and SMPS were not noticeably elevated during CNT-PTFE composite work. Instant increase of number concentrations of nano-sized particles was observed during manual sanding of CNT-PTFE composites. Both number concentrations and mean diameters did not show a statistically significant difference between workers handing CNT-added and not-added materials. TEM analyses revealed the emission of free-standing CNTs and CNT-PTFE aggregate particles from the powder supply task and composite particles embedded with CNTs from the computer numerical control(CNC) machining task with more than tens of micrometers in diameter. No free-standing CNT particles were observed from the CNC machining task. Conclusions: Significant worker exposure to respirable CNTs was not found, but the aerosolization of CNTs and CNT-embedded composite particles were observed during handing of CNT-PTFE powders and CNC machining of CNT-PTFE composites. Considering the limited knowledge on the toxicity of CNTs and CNT composite particles to date, it seems prudent to take a precautionary approach for the protection of workers' health.

• Journal of Environmental Health Sciences
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• v.34 no.4
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• pp.279-284
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• 2008

This paper aims to provide basic data for work environment control, prevention of worker exposure to asbestos and improvement of air quality to protect workers ‘health after measuring the level of airborne asbestos and workers' exposure in a shipbuilding repair businesses. For this study, a total of 27 samples were collected from 27 workers who had been exposed to asbestos during engine, piping, boiler and other manufacturing processes in 'A' Shipbuilding Repair Company in Gyeongnam. This research was conducted from Oct. 1 to 30, 2007 and had the following results: The target group (27 workers) consisted of all men with an average age of 35.9 years and 6.6 years of work on average. Among them, fifteen 15 (55.6%) were smokers. In terms of their duties at work, there were 12 plumbing repair engineers (44.4%), 8 boiler repair engineers (29.6%) and 7 engine engineers (25.9%). The geometric mean concentration of airborne asbestos was 0.004 f/cc. A total of 4 samples exceeded the exposure limit. In particular, three exceeded the legal limit by more than double, which means that some workers have been highly exposed to asbestos. In terms of the concentration of asbestos fibres by work process, plumbing repair was the highest (0.0071 f/cc($0.001{\sim}0.57\;f/cc$)) while boiler was the lowest (0.0015 f/cc($0.001{\sim}0.007\;f/cc$)). Based on this study, proper action needs to be taken as soon as possible to protect workers from the threat of asbestos.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.34 no.2
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• pp.156-165
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• 2024

Objectives: This study aims to identify and analyze the exposure status of welding students in specialized high school welding labratories, compare it with the exposure to welding hazards of industrial workers, and seek to improve the educational environment for youth through domestic and international exposure standards. Methods: This study compares the level of exposure to hazardous factors in a welding laboratory of a vocational high school in Jeollanam-do and a welding process in a general industrial site by measuring the work environment. A 10-question survey was conducted to review the effects of welding hazards on the human body, carcinogenicity information, international (US, UK, France) exposure standards, general characteristics between the two groups, and awareness of occupational health. Results: Exposure to hazardous factors in both groups was below the standards set by MOEL. Specialized high school students were exposed to higher levels than workers, and some hazardous factors exceeded the standards when compared to international exposure standards. During the survey, students were less aware of the hazards of welding, safety and health education, and the need for work environment measurement than workers. Conclusions: For the respiratory protection of students in vocational high school welding labs, it is necessary to create a comfortable training environment. Exposure standards for harmful factors should be strictly applied, such as overseas standards, or exposure should be limited by setting a limit on the number of hours of welding practice per week. In addition, it is necessary to conduct safety and health education for welding students to raise their awareness of the importance of measuring the working environment and wearing appropriate protective equipment.

• Journal of the Ergonomics Society of Korea
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• v.34 no.3
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• pp.217-222
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• 2015

Objective:The objective of this study is to review the exposure limits in the legislation, guidelines, and standards for human vibration in Korea. Background: There have been relatively less interests in vibration than other risk factors in Korea. However, the importance of vibration is increasing as industry and everyday life are more mechanized. Method: Various enforcements were examined including legislation, guidelines, and standards for whole-body vibration and localized vibration. Results: No exposure limits were found in legislation, guidelines, and standards for the human vibration in Korea. Conclusion: It is important to introduce new duties regarding vibration risks to the general duties. Further studies are expected on the vibration exposure limits appropriate for Korean people and job conditions. Application: The results from this study would be of help to induce more interests in human vibration to the occupational health and safety professionals of Korea.

• Journal of Environmental Health Sciences
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• v.14 no.2
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• pp.13-27
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• 1988

Two asbestos slate manufacturing and seven asbestos textile plants in Korea were surveyed from May 20 to July 2, 1987. The purposes of this study were to evaluate 1) worker exposure to asbestos, 2) compliance to the standards and 3) the efficiency of existing local exhaust systems. Sixty-two personal samples and eighty-three area samples were collected and analyzed using "NIOSH 7400" method. Results of this study were as follows. 1. The asbesots exposure concentrations in asbestos textile plants were 1.3 - 14.3 fibers/cc(geometric mean(GM), 4.4 fibers/cc). 2. Worker exposure level to asbestos fiber in asbestos slate manufacturing industry was 0.21 fibers/cc during wet processing, which is below the Korean Standard of 2 fibers/cc. 3. Most local exhaust systems installed in asbestos textile plants were inadequately designed. 4. Ninety-six percent of the 145 samples exceeded the U.S. Occupational Safety and Health Administration (OSHA) Permissible Exposure Limit (PEL) of 0.2 fibers/cc and forty-nine percent of the samples exceeded the Korean Standatd of 2 fibers/cc.

• Journal of the Korean Society of Mechanical Technology
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• v.13 no.2
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• pp.107-113
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• 2011

This study was performed for the application of the exposure limit in work field and the relative noxious gas concentration was estimated by using a miniature ship. The noxious gas concentration about light and shade number distribution of measuring subject field was estimated by using floating visualization image from a miniature ship in a large wind tunnel. About the concentration estimation, the correlation of concentration distribution drawn from the existing experimental results was used, the estimation result satisfied LTEL standard.