Donguk Park

Characteristics of PM10, PM2.5, CO2 and CO monitored in interiors and platforms of subway train in Seoul, Korea

This study was performed to investigate the concentration of PM(10) and PM(2.5) inside trains and platforms on subway lines 1, 2, 4 and 5 in Seoul, KOREA. PM(10), PM(2.5), carbon dioxide (CO(2)) and carbon monoxide (CO) were monitored using real-time monitoring instruments in the afternoons (between 13:00 and 16:00). The concentrations of PM(10) and PM(2.5) inside trains were significantly higher than those measured on platforms and in ambient air reported by the Korea Ministry of Environment (Korea MOE). This study found that PM(10) levels inside subway lines 1, 2 and 4 exceeded the Korea indoor air quality (Korea IAQ) standard of 150 microg/m(3). The average percentage that exceeded the PM(10) standard was 83.3% on line 1, 37.9% on line 2 and 63.1% on line 4, respectively. PM(2.5) concentration ranged from 77.7 microg/m(3) to 158.2 microg/m(3), which were found to be much higher than the ambient air PM(2.5) standard promulgated by United States Environmental Protection Agency (US-EPA) (24 h arithmetic mean: 65 microg/m(3)). The reason for interior PM(10) and PM(2.5) being higher than those on platforms is due to subway trains in Korea not having mechanical ventilation systems to supply fresh air inside the train. This assumption was supported by the CO(2) concentration results monitored in tube of subway that ranged from 1153 ppm to 3377 ppm. The percentage of PM(2.5) in PM(10) was 86.2% on platforms, 81.7% inside trains, 80.2% underground and 90.2% at ground track. These results indicated that fine particles (PM(2.5)) accounted for most of PM(10) and polluted subway air. GLM statistical analysis indicated that two factors related to monitoring locations (underground and ground or inside trains and on platforms) significantly influence PM(10) (p<0.001, R(2)=0.230) and PM(2.5) concentrations (p<0.001, R(2)=0.172). Correlation analysis indicated that PM(10), PM(2.5), CO(2) and CO were significantly correlated at p<0.01 although correlation coefficients were different. The highest coefficient was 0.884 for the relationship between PM(10) and PM(2.5).

Indoor air quality differences between urban and rural preschools in Korea

Background, aims, and scopePreschool indoor air quality (IAQ) is believed to be different from elementary school or higher school IAQ and preschool is the first place for social activity. Younger children are more susceptible than higher-grade children and spend more time indoors. The purpose of this study was to compare the indoor air quality by investigating the concentrations of airborne particulates and gaseous materials at preschools in urban and rural locations in Korea.MethodsWe investigated the concentrations of airborne particulates and gaseous materials in 71 classrooms at 17 Korean preschools. For comparison, outdoor air was sampled simultaneously with indoor air samples. Airborne concentrations of total suspended particulates, respirable particulates, lead, asbestos, total volatile organic compounds and components, formaldehyde, and CO2 were measured with National Institute for Occupational Safety and Health and/or Environmental Protection Agency analytical methods.ResultsThe concentration profiles of the investigated pollutants in indoor and urban settings were higher than those in outdoor and rural areas, respectively. The ratios of indoor/outdoor concentrations (I/O) of particulates and gaseous pollutants were characterized in urban and rural preschools. Total dust concentration was highest in urban indoor settings followed by urban outdoor, rural indoor, and rural outdoor locations with an I/O ratio of 1.37 in urban and 1.35 in rural areas. Although I/O ratios of lead were close to 1, lead concentrations were much higher in urban than in rural areas. The I/O ratio of total VOCs was 2.29 in urban and 2.52 in rural areas, with the highest level in urban indoor settings. The I/O ratio of formaldehyde concentrations was higher in rural than in urban areas because the outdoor rural level was much lower than the urban concentration. Since an I/O ratio higher than 1 implies the presence of indoor sources, we concluded that there are many indoor sources in preschools.ConclusionsWe confirmed that pollutants in indoor and urban settings were higher than those in outdoor and rural areas, respectively. Preschool children are expected to spend more time inside preschool facilities and therefore to be more exposed to pollutants. As far as we know, preschool IAQ is different from elementary school or higher school IAQ. Also, they are more vulnerable than higher-grade children. We found that the indoor and urban concentration profiles of the studied pollutants in preschools were higher than those in outdoor and rural areas. We believe that our findings may be useful for understanding the potential health effects of exposure and intervention studies in preschools.

Assessment of the Levels of Airborne Bacteria, Gram-Negative Bacteria, and Fungi in Hospital Lobbies

Aims: We assessed the levels of airborne bacteria, Gram-negative bacteria (GNB), and fungi in six hospital lobbies, and investigated the environmental and hospital characteristics that affected the airborne microorganism levels. Methods: An Andersen single-stage sampler equipped with appropriate nutrition plate agar was used to collect the samples. The three types of microorganisms were repeatedly collected at a fixed location in each hospital (assumed to be representative of the entire hospital lobby) from 08:00 through 24:00, with a sampling time of less than 5 min. Temperature and relative humidity were simultaneously monitored. Results: Multiple regression analysis was used to identify the major factors affecting microorganism levels. The average levels of bacteria (7.2 × 102 CFU/m3), GNB (1.7 × 10 CFU/m3), and fungi (7.7 × 10 CFU/m3) indicated that all hospital lobbies were generally contaminated. Season was the only factor that significantly affected the levels of all microorganisms (p < 0.0001), where contamination was the highest during the summer, significantly higher than during the winter. Other significant factors varied by microorganism, as follows: airborne bacteria (number of people in the lobby, sampling time), GNB (scale of hospital), and fungi (humidity and air temperature). Conclusions: Hospital lobby air was generally contaminated with microorganisms, including bacteria, GNB, and fungi. Environmental factors that may significantly influence the airborne concentrations of these agents should be managed to minimize airborne levels.

A Comprehensive Review of Arsenic Levels in the Semiconductor Manufacturing Industry

This paper presents a summary of arsenic level statistics from air and wipe samples taken from studies conducted in fabrication operations. The main objectives of this study were not only to describe arsenic measurement data but also, through a literature review, to categorize fabrication workers in accordance with observed arsenic levels. All airborne arsenic measurements reported were included in the summary statistics for analysis of the measurement data. The arithmetic mean was estimated assuming a lognormal distribution from the geometric mean and the geometric standard deviation or the range. In addition, weighted arithmetic means (WAMs) were calculated based on the number of measurements reported for each mean. Analysis of variance (ANOVA) was employed to compare arsenic levels classified according to several categories such as the year, sampling type, location sampled, operation type, and cleaning technique. Nine papers were found reporting airborne arsenic measurement data from maintenance workers or maintenance areas in semiconductor chip-making plants. A total of 40 statistical summaries from seven articles were identified that represented a total of 423 airborne arsenic measurements. Arsenic exposure levels taken during normal operating activities in implantation operations (WAM = 1.6 μg m⁻³, no. of samples = 77, no. of statistical summaries = 2) were found to be lower than exposure levels of engineers who were involved in maintenance works (7.7 μg m⁻³, no. of samples = 181, no. of statistical summaries = 19). The highest level (WAM = 218.6 μg m⁻³) was associated with various maintenance works performed inside an ion implantation chamber. ANOVA revealed no significant differences in the WAM arsenic levels among the categorizations based on operation and sampling characteristics. Arsenic levels (56.4 μg m⁻³) recorded during maintenance works performed in dry conditions were found to be much higher than those from maintenance works in wet conditions (0.6 μg m⁻³). Arsenic levels from wipe samples in process areas after maintenance activities ranged from non-detectable to 146 μg cm⁻², indicating the potential for dispersion into the air and hence inhalation. We conclude that workers who are regularly or occasionally involved in maintenance work have higher potential for occupational exposure than other employees who are in charge of routine production work. In addition, fabrication workers can be classified into two groups based on the reviewed arsenic exposure levels: operators with potential for low levels of exposure and maintenance engineers with high levels of exposure. These classifications could be used as a basis for a qualitative ordinal ranking of exposure in an epidemiological study.

Task-based exposure assessment of nanoparticles in the workplace

Although task-based sampling is, theoretically, a plausible approach to the assessment of nanoparticle exposure, few studies using this type of sampling have been published. This study characterized and compared task-based nanoparticle exposure profiles for engineered nanoparticle manufacturing workplaces (ENMW) and workplaces that generated welding fumes containing incidental nanoparticles. Two ENMW and two welding workplaces were selected for exposure assessments. Real-time devices were utilized to characterize the concentration profiles and size distributions of airborne nanoparticles. Filter-based sampling was performed to measure time-weighted average (TWA) concentrations, and off-line analysis was performed using an electron microscope. Workplace tasks were recorded by researchers to determine the concentration profiles associated with particular tasks/events. This study demonstrated that exposure profiles differ greatly in terms of concentrations and size distributions according to the task performed. The size distributions recorded during tasks were different from both those recorded during periods with no activity and from the background. The airborne concentration profiles of the nanoparticles varied according to not only the type of workplace but also the concentration metrics. The concentrations measured by surface area and the number concentrations measured by condensation particle counter, particulate matter 1.0, and TWA mass concentrations all showed a similar pattern, whereas the number concentrations measured by scanning mobility particle sizer indicated that the welding fume concentrations at one of the welding workplaces were unexpectedly higher than were those at workplaces that were engineering nanoparticles. This study suggests that a task-based exposure assessment can provide useful information regarding the exposure profiles of nanoparticles and can therefore be used as an exposure assessment tool.

A comprehensive review of the literature on exposure to metalworking fluids.

An extensive literature review was conducted of studies with exposure measurements to metalworking fluids (MWFs). A database of 155 arithmetic means based on 9379 aerosol measurements from published studies was compiled. Weighted arithmetic means (WAMs) and their variance calculated across studies were summarized based on decade (prior to 1970s through 2000s), industry (auto, auto parts, small job shops, and others), operation (grinding and machining), and fluid type (straight, soluble, synthetic, and semisynthetic). Total mass and total extractable mass measurements that were simultaneously collected were compared. Average concentrations by size fractions and mass median aerodynamic diameters (MMADs) were also analyzed. Analysis of the WAMs indicated a reduction in exposure levels over time regardless of industry or type of operation or fluid, with mean levels prior to the 1970s of 5.4 mg/m3, which dropped to 2.5 mg/m3 in the 1970s, to 1.2 mg/m3 in the 1980s, and to 0.5 mg/m3 in the 1990s. No further reduction was seen in the 2000s. A comparison by industry, operation, and fluid type found no consistent patterns in the measurement results. The percent extractable mass in the total aerosol samples varied by fluid type, with an average 84% in straight fluids, 58% in synthetic fluids, 56% in soluble fluids, and 42% in the semisynthetic fluids. Exposure means from the thoracic fraction (0.3–0.5 mg/m3) were slightly less than those for total aerosol for both the 1990s and 2000s, the only decades for which thoracic data were available. Respirable means did not change from the 1980s to the 2000s (generally about 0.2–0.3 mg/m3). The MMADs of the MWF aerosols averaged 4–6 μm. These measurement data indicate a clear reduction of exposure levels over time. They will be used for the retrospective assessment of exposure levels to MWFs in a population-based, case-control study of bladder cancer.

Estimating retrospective exposure of household humidifier disinfectants.

UNLABELLED We conducted a comprehensive humidifier disinfectant exposure characterization for 374 subjects with lung disease who presumed their disease was related to humidifier disinfectant use (patient group) and for 303 of their family members (family group) for an ongoing epidemiological study. We visited the homes of the registered patients to investigate disinfectant use characteristics. Probability of exposure to disinfectants was determined from the questionnaire and supporting evidence from photographs demonstrating the use of humidifier disinfectant, disinfectant purchase receipts, any residual disinfectant, and the consistency of their statements. Exposure duration was estimated as cumulative disinfectant use hours from the questionnaire. Airborne disinfectant exposure intensity (μg/m(3)) was estimated based on the disinfectant volume (ml) and frequency added to the humidifier per day, disinfectant bulk level (μg/ml), the volume of the room (m(3)) with humidifier disinfectant, and the degree of ventilation. Overall, the distribution patterns of the intensity, duration, and cumulative exposure to humidifier disinfectants for the patient group were higher than those of the family group, especially for pregnant women and patients ≤6 years old. Further study is underway to evaluate the association between the disinfectant exposures estimated here with clinically diagnosed lung disease. PRACTICAL IMPLICATIONS Retrospective exposure to household humidifier disinfectant as estimated here can be used to evaluate associations with clinically diagnosed lung disease due to the use of humidifier disinfectant in Korea. The framework, with modifications to account for dispersion and use patterns, can also be potentially adapted to assessment of other household chemical exposures.

Nationwide Study of Humidifier Disinfectant Lung Injury in South Korea, 1994-2011. Incidence and Dose-Response Relationships.

RATIONALE Humidifier disinfectant lung injury is an acute lung disease attributed to recurrent inhalation of certain disinfectant aerosols emitted from room humidifiers. An outbreak of this toxic lung injury occurred in South Korea from 1995 until all humidifier disinfectant products were recalled from the consumer market by the government in 2011. OBJECTIVES A nationwide study was conducted to ascertain and classify all potential cases of humidifier disinfectant lung injury in Korea and to assess dose-response relationships. METHODS By several mechanisms, clinicians and the general public were invited to report all suspected cases of humidifier disinfectant lung injury to public health officials in South Korea. A committee was convened to define diagnostic criteria based on pathologic, radiologic, and clinical findings for index cases, combined with assessment of environmental exposure to humidifier disinfectants. Clinical review and environmental assessments were performed and later combined to determine overall likelihood of disease for each study participant, classified as definite, probable, possible, or unlikely. Survival time from exposure to onset of symptoms was analyzed to assess dose-response relationships. Three broad categories of risk factors were examined: (1) biological susceptibility, (2) temporal cycle of exposure and recovery, and (3) spatial conditions and density of disinfectant. MEASUREMENTS AND MAIN RESULTS Of 374 possible cases identified and reviewed, 329 were unanimously classified by the diagnostic committee, as follows: 117 definite, 34 probable, 38 possible and 140 unlikely cases. A total of 62 individuals with definite or probable disease died. Risk factors examined for polyhexamethyleneguanidine phosphate exposure that were found to be significant in shortening survival included age 4 years or younger at onset, use of disinfectant for 7 days per week, airborne density of 800 μg/m(3) or more of disinfectant, and daily exposure 11 or more hours in duration. CONCLUSIONS Dose-response analysis indicated that development of humidifier disinfectant lung injury and death were associated strongly with recurrent, intense, acute exposure without sufficient recovery time between exposures, more so than long-term cumulative exposure. These findings may explain some reversible or clinically unapparent cases among coexposed family members.

Association between Use of Synthetic Metalworking Fluid and Risk of Developing Rhinitis-related Symptoms in an Automotive Ring Manufacturing Plant

Association between Use of Synthetic Metalworking Fluid and Risk of Developing Rhinitis‐related Symptoms in an Automotive Ring Manufacturing Plant: Dong‐Uk Park, et al. Department of Environmental Health, Korea National Open University, Korea—The main objective of this study was to determine the association between synthetic metalworking fluid (MWF) and rhinitis‐related symptoms. At a plant manufacturing piston rings for automobiles, we interviewed grinders (19) and manufacturing workers (142) in operations where synthetic or semisynthetic MWF is handled, and administrative office workers (44) regarding the principal symptoms of rhinitis (nasal stuffiness, runny nose, anosmia, nasal itchiness, rhinorrhea, headache, epistaxis, and post‐nasal drip). In addition, we assessed the current exposure of workers handling MWF to MWF aerosols, fungi, and endotoxins. Logistic regression analysis was used to examine the association between MWF surrogates indicative of MWF exposure and each rhinitis‐related nasal symptom. Odds ratios (ORs) and 95% confidence intervals were adjusted for sex, age, smoking habit, and duration of employment. Among grinders handling synthetic MWF, the frequency of complaints of the dominant symptoms was 66.7% for nasal stuffiness, 77.8% for anosmia, 77.8% for runny nose, and 50.0% for headache. These rates are quite high even allowing for the common occurrence of rhinitis in the general population. Twenty eight of 34 grinding and manufacturing workers (82.4%) sampled were exposed to MWF mist above the threshold limit of 0.2 mg/m3listed as a notice of intended change by the American Conference for Governmental Industrial Hygienists (ACGIH). The percentage of workers exposed to MWF mist >0.5 mg/m3was 17.6%. Most workers were exposed to fungi levels >103CFU/m3. All exposures to endotoxins were <50 EU/m3. Logistic regression analysis found that use of synthetic MWF was significantly associated with excess risk of nasal stuffiness (OR 3.5), nasal itchiness (OR 2.0), and runny nose (OR 2.1). The use of semi‐synthetic MWF had little or no impact on the risk of developing rhiniti‐srelated nasal symptoms. Grinding workers handling synthetic MWF had an increased risk of nasal stuffiness (OR 7.9), anosmia (OR 23.2), nasal itchiness (OR 8.3), runny nose (OR 20.4), post nasal drip (OR 18.4), and headache (OR 7.4) compared to administrative workers. Synthetic MWF may play an important role in the development of the dominant symptoms of rhinitis. Further study is needed to establish the risk of rhinitis or rhinitis‐related symptoms according to MWF type.

Exposure Assessment to Suggest the Cause of Sinusitis Developed in Grinding Operations Utilizing Soluble Metalworking Fluids

Exposure Assessment to Suggest the Cause of Sinusitis Developed in Grinding Operations Utilizing Soluble Metalworking Fluids: Donguk Park et al. Korea National Open University, Korea—A worker who ground the inner parts of camshafts for automobile engines using water‐soluble metalworking fluid (MWF) for 14 yr was diagnosed with sinusitis. We postulated that the cause of sinusitis might be associated with exposure to microbes contaminating the water‐soluble MWF used in the grinding operation. To uncover responsible agents for this case of sinusitis, a quantitative exposure assessment for chemical and biological agents was made and prevalence of work‐related respiratory symptoms was investigated by questionnaire. The exposure ranges of MWF mist (0.59 mg/m3 to 2.12 mg/ m3) measured during grinding exceeded 0.5 mg/m3 of the recommended exposure limit (REL). Grinders’ exposures to bacteria, fungi and endotoxins were also generally higher than not only the proposed standards, but also those reported by several studies investigating the causes of respiratory effects. Statistical tests indicated that the prevalence rate of reported symptoms related to nasal cavities showed no significant differences among the operations. Evaluation of grinding operation characteristics and the quantitative exposure assessment indicated that repeated exposure to MWF mist, including water‐soluble MWF contaminated with microbes may cause respiratory diseases like sinusitis or at least increase susceptibility to the development of sinusitis. Further study is underway to identify environmental risk factors for sinusitis by analyzing the relationship between medical examination results and plant characteristics including exposure data.