• Safety and Health at Work
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• v.10 no.3
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• pp.377-383
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• 2019

Objectives: Exposure to fine particles in urban air has been associated with a number of negative health effects. High levels of fine particles have been detected at underground stations in big cities. We investigated the exposure conditions in four occupational groups in the Stockholm underground train system to identify high-exposed groups and study variations in exposure. Methods: $PM_1$ and $PM_{2.5}$ were measured during three full work shifts on 44 underground workers. Fluctuations in exposure were monitored by a real-time particle monitoring instrument, pDR, DataRAM. Qualitative analysis of particle content was performed using inductively coupled plasma mass spectrometry. Nitrogen dioxide was measured using passive monitors. Results: For all underground workers, the geometric mean (GM) of $PM_1$ was $18{\mu}g/m^3$ and of $PM_{2.5}$ was $37{\mu}g/m^3$. The particle exposure was highest for cleaners/platform workers, and the GM of $PM_1$ was $31.6{\mu}g/m^3$ [geometric standard deviation (GSD), 1.6] and of $PM_{2.5}$ was $76.5{\mu}g/m^3$ (GSD, 1.3); the particle exposure was lowest for ticket sellers, and the GM of $PM_1$ was $4.9{\mu}g/m^3$ (GSD, 2.1) and of $PM_{2.5}$ was $9.3{\mu}g/m^3$ (GSD, 1.5). The $PM_1$ and $PM_{2.5}$ levels were five times higher in the underground system than at the street level, and the particles in the underground had high iron content. The train driver's nitrogen dioxide exposure level was $64.1{\mu}g/m^3$ (GSD, 1.5). Conclusions: Cleaners and other platform workers were statistically significantly more exposed to particles than train drivers or ticket sellers. Particle concentrations ($PM_{2.5}$) in the Stockholm underground system were within the same range as in the New York underground system but were much lower than in several older underground systems around the world.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.23 no.4
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• pp.412-420
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• 2013

Objectives: This study was conducted in order to evaluate personal and area exposure to airborne total dust and endotoxin during harvest and planting tasks at cucumber, yellow melon and potato farms Materials and Methods: Total dust was measured with NIOSH method 0500. Endotoxin were measured using a 37 mm glass fiber filter which was connected to an air pump calibrated to 2 LPM, and then analyzed with a Turbidmetric kinetic method. Results: The average(arithmetic mean) concentrations of total dust in the personal samples were $0.10-3.81mg/m^3$ for cucumbers, $0.21-1.19mg/m^3$ for yellow melon, and $0.08-2.72mg/m^3$ for potato. There was a significant difference in the harvest task among the three farm types(p=0.019 of personal sample, p=0.048 of area sample), in which the air concentration for potatoes was higher than with cucumbers and yellow melons. Conclusions: It was found that potatoes(planting and harvest) should be considered the first priority for studying and reducing total dust exposure.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.4 no.1
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• pp.81-95
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• 1994

This study was performed in a diatomite factory where silicosis had been found at October, 1993. The major objectives were to evaluate worker exposure to diatomaceous earth and to present engineering control methods for workplace management. Total and respirable dust of diatomaceous earth were measured. Size distribution of dust was analyzed by applying the multiple diffraction method. Also crystalline silica in respirable dust samples was analyzed qualitatively by X-ray diffraction. The suitable Local Exhaust Ventilation systems for that factory were recommended. The results were as follows. The airborne total and respirable dust concentrations by exposure groups showed approximate normal distribution. The means of total dust exposures at flour maufacturing, fire brick grinding and packaging, ceramic raws packaging processes exceeded Korean and ACGIH standards, $10mg/m^3$. The means of total and respirable dust concentrations to high exposure groups were 6.8 and 3.9 times higher than those of low expousre groups, respectively. The size distribution of diatomaceous earth dust was lognormal with a median diameter of $7.07{\mu}m$(range, $0.10-60.0{\mu}m$) and with a geometric standard deviation of 1.43. The crystalline silica in respirable dust samples was identified to quartz and cristobalite and/or tridymite. Above results suggest that engineering controls and periodic environmental and medical surveillances will be important for preventing silicosis in the diatomite factory.

• Environmental Analysis Health and Toxicology
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• v.20 no.3 s.50
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• pp.215-221
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• 2005

Environmental polycyclic aromatic hydrocarbones (PAHs), which are formed during incomplete combustion of fossil fuels, are widely distributed in our environment. Human exposure to PAHs may occur through smoking, polluted air, food consumption and occupational contact. Urinary naphthols, 1-and 2-naphthol, have been suggested as route -specific biomarkers for exposure to airborne PAHs. Cytochrome p450 2E1 (CYP2E1) is known to be a great importance for the metabolism of organic solvents, which is a precacinogens with small molecular weight. This study describes the metabolic differences between PstI and RsaI polymorphisms (c1 allele: PstI-. RsaI+ ; c2 allele: PstI+, RsaI-) of CYP2E1 5-flanking region by genetically modified HepG2 cells, which overexpress the polymorphic regions. The results of CAT assay and western blot in the c2 allele overexpressed cells have higher activities than the cl allele over-expressing cells. However, the metabolism of naphthalene to 2-naphthol has no difference due to the two genotypes. In this study, we established the CYP2E1 polymorphic allele transduced HepG2 cells to screen susceptibility -differences in PAH exposure. In conclusion, the CYP2E1 polymorphism may hardly induce susceptibility differences in PAH exposure monitoring with urinary naphthols.

• Journal of Environmental Health Sciences
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• v.44 no.6
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• pp.524-538
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• 2018

Objective: This study aimed to identify the size distributions of particulate matter emitted during 3D printing according to operational conditions and estimate particle inhalation exposure doses at each respiratory region. Methods: Four types of printing filaments were selected: acrylonitrile-butadiene-styrene (ABS), polylactic acid (PLA), Laywood, and nylon. A fused deposition modeling (FDM) 3D printer was used for printing. Airborne particles between 10 nm and $10{\mu}m$ were measured before, during, and after printing using real-time monitors under extruder temperatures from 215 to $290^{\circ}C$. Inhalation exposures, including inhaled and deposited doses at the respiratory regions, were estimated using a mathematical model. Results: Nanoparticles dominated among the particles emitted during printing, and more particles were emitted with higher temperatures for all materials. Under all temperature conditions, the Laywood emitted the highest particle concentration, followed by ABS, PLA, and nylon. The particle concentration peaked for the initial 10 to 20 minutes after starting operations and gradually decreased with elapsed time. Nanoparticles accounted for a large proportion of the total inhaled particles in terms of number, and about a half of the inhaled nanoparticles were estimated to be deposited in the alveolar region. In the case of the mass of inhaled and deposited dose, particles between 0.1 and $1.0{\mu}m$ made up a large proportion. Conclusion: The number of consumers using 3D printers is expected to expand, but hazardous emissions such as thermal byproducts from 3D printing are still unclear. Further studies should be conducted and appropriate control strategies considered in order to minimize human exposure.

• Safety and Health at Work
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• v.15 no.1
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• pp.87-95
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• 2024

Background: This study focuses on assessing occupational risk for the health hazards encountered during maintenance works (MW) in semiconductor fabrication (FAB) facilities. Objectives: The objectives of this study include: 1) identifying the primary health hazards during MW in semiconductor FAB facilities; 2) reviewing the methods used in evaluating the likelihood and severity of health hazards through occupational health risk assessment (OHRA); and 3) suggesting variables for the categorization of likelihood of exposures to health hazards and the severity of health effects associated with MW in FAB facilities. Methods: A literature review was undertaken on OHRA methodology and health hazards resulting from MW in FAB facilities. Based on this review, approaches for categorizing the exposure to health hazards and the severity of health effects related to MW were recommended. Results: Maintenance workers in FAB facilities face exposure to hazards such as debris, machinery entanglement, and airborne particles laden with various chemical components. The level of engineering and administrative control measures is suggested to assess the likelihood of simultaneous chemical and dust exposure. Qualitative key factors for mixed exposure estimation during MW include the presence of safe operational protocols, the use of air-jet machines, the presence and effectiveness of local exhaust ventilation system, chamber post-purge and cooling, and proper respirator use. Using the risk (R) and hazard (H) codes of the Globally Harmonized System alongside carcinogenic, mutagenic, or reprotoxic classifications aid in categorizing health effect severity for OHRA. Conclusion: Further research is needed to apply our proposed variables in OHRA for MW in FAB facilities and subsequently validate the findings.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.20 no.4
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• pp.225-235
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• 2010

This study was aimed to assess the status of working environment, health care management status and cause of exposure in manufactories using dimethylformamide (DMF). For the purpose, airborne concentration of DMF in the workplaces and N-methylformamide (NMF) in worker's urine were measured with job type and process. In addition, management of local exhaust ventilation system (LEV) and personal protective equipment (PPE) was evaluated at 35 work places (107 workers) located in Busan and Gimhae area. Mean DMF concentrations in work places by job type and process were of high level measured in printing and record media reproduction (5.23 ppm) and flaking process (2.48 ppm). Workers in adhesive job were measured a large amount of urine NMF (21.59 mg/${\ell}$). 98.1% of DMF handling workers were provided respirators, but 67.3% of those workers used them. The main reasons for not using respirators were inconvenience and difficulty of breathing. Airborne concentrations of DMF were higher in the workplaces in which LEVs were working abnormally, but there was not statistically significant. In addition, the urine NMF levels were correlated with management of LEV within the workers who did not use the respirators (p<0.048). These results implied that LEV should be installed and maintained properly to protect the workers from the exposure to DMF. Management of PPE should be also necessary to protect the workers from chemical hazards.

• 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 the Korea institute for structural maintenance and inspection
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• v.23 no.3
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• pp.119-126
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• 2019

In case of RC(Reinforced Concrete) structures which are constructed in coastal areas, chloride ions in sea water corrode the steel rebar in concrete. Especially in coastal areas, RC structures are affected by not only immersion of sea water, but also tidal of sea water and airborne chloride ions. In this study, marine environment exposure tests are conducted, considering 3 types of exposure environments(immersion zone, tidal zone, splash zone) and the exposure periods of 180 days, 365 days, and 730 days. Also, the concrete mixtures for this study are established, considering 3 levels of W/B(Water to Binder) ratio(0.37, 0.42, 0.47) and 2 levels of substitution rate of Fly ash(0 %, 30 %). In all exposure environments, Fly ash concrete has lower apparent chloride diffusion coefficients than OPC concrete. It is thought that fly ash's pozzolan reaction improves chloride resistance of concrete. Fly ash concrete has up to 63.5 % of decreasing rate in 180 days of exposure and up to 55.8 % of decreasing rate in 730 days of exposure, based on diffusion coefficients of OPC concrete. As a result of evaluation about effects of exposure environments, apparent chloride diffusion coefficients of fly ash concrete are evaluated in order of tidal zone, immersion zone, and splash zone. In tidal zone, It is thought that repeated cycles of wetting and drying of sea water cause the diffusion of chloride ions rapidly.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.24 no.4
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• pp.471-477
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• 2014

Objectives: This study was conducted to evaluate area exposure of airborne dust and organic gas during entrance and shipment of chicken in poultry farms Methods: Total dust was measured with NIOSH method 0500. The volume of distributed dust and organic gas(Ammonia, TVOC, Hydrogen Sulfide) were measured using direct reading instrument. Results: The range of concentrations of total dust in area sample was $0.07{\sim}4.91mg/m^3$ during the entrance of chicks and $4.37{\sim}9.4mg/m^3$ during shipment respectively. Concentration of ammonia reached approximately 9 ppm during shipment. There was a difference of concentration of total dust in the area sample between shipment and entrance tasks. Conclusions: It was found that the development of a special intervention program by type of task should be considered for reducing respiratory health effects among poultry farmers.