Comparison of Nanoparticle Exposure Levels Based on Facility Type-Small-Scale Laboratories, Large-Scale Manufacturing Workplaces, and Unintended Nanoparticle-Emitting Workplaces

Ham, Seunghon,Kim, Sunju,Lee, Naroo,Kim, Pilje,Eom, Igchun,Tsai, Perng-Jy,Lee, Kiyoung,Yoon, Chungsik Taiwan Association for Aerosol Research 2015 Aerosol and air quality research Vol.15 No.5

Comparison of data analysis procedures for real-time nanoparticle sampling data using classical regression and ARIMA models

Ham, Seunghon,Kim, Sunju,Lee, Naroo,Kim, Pilje,Eom, Igchun,Lee, Byoungcheun,Tsai, Perng-Jy,Lee, Kiyoung,Yoon, Chungsik Informa UK (TaylorFrancis) 2017 Journal of applied statistics Vol.44 No.4

<P>Real-time monitoring is necessary for nanoparticle exposure assessment to characterize the exposure profile, but the data produced are autocorrelated. This study was conducted to compare three statistical methods used to analyze data, which constitute autocorrelated time series, and to investigate the effect of averaging time on the reduction of the autocorrelation using field data. First-order autoregressive (AR(1)) and autoregressive-integrated moving average (ARIMA) models are alternative methods that remove autocorrelation. The classical regression method was compared with AR(1) and ARIMA. Three data sets were used. Scanning mobility particle sizer data were used. We compared the results of regression, AR(1), and ARIMA with averaging times of 1, 5, and 10min. AR(1) and ARIMA models had similar capacities to adjust autocorrelation of real-time data. Because of the non-stationary of real-time monitoring data, the ARIMA was more appropriate. When using the AR(1), transformation into stationary data was necessary. There was no difference with a longer averaging time. This study suggests that the ARIMA model could be used to process real-time monitoring data especially for non-stationary data, and averaging time setting is flexible depending on the data interval required to capture the effects of processes for occupational and environmental nano measurements.</P>

Arsenic Exposure during Preventive Maintenance of an Ion Implanter in a Semiconductor Manufacturing Factory

Ham, Seunghon,Yoon, Chungsik,Kim, Sunju,Park, Jihoon,Kwon, Ohun,Heo, Jungjin,Park, Donguk,Choi, Sangjun,Kim, Seungwon,Ha, Kwonchul,Kim, Won Taiwan Association for Aerosol Research 2017 Aerosol and air quality research Vol.17 No.4

Prevention of exposure to and spread of COVID-19 using air purifiers: challenges and concerns

Seunghon Ham 한국역학회 2020 Epidemiology and Health Vol.42 No.-

Coronavirus disease 2019 (COVID-19) is now a pandemic. The Korean government has declared a red alert, which is the highest level of the national infectious disease alert system, and the World Health Organization has similarly declared its highest-level pandemic alert (phase 6). The spread of COVID-19 is an unprecedented worldwide public health problem that governments and individuals must work to overcome. Recently, an infection cluster arose in a call center in Seoul. To support call center companies, the Korean Ministry of Employment and Labor has proposed covering the costs of installing partitions and air purifiers, providing hand sanitizers, and supplying masks to prevent droplet and aerosol infections. Air purifiers are expected to be installed on the floor with the exhaust outlets at a higher level, such as the level of the desks or breathing zones of workers. When a worker coughs or releases droplets near a colleague’s respiratory system, the droplets may spread throughout the call center via air flow from air purifier. In this fashion, a single infected person can give rise to an infection cluster. Attempts to prevent infection must not lead to new infections, and the installation of air purifiers may cause new problems. Therefore, using air purifiers to control the spread of COVID-19 should be approached with caution.

Comparison of Real Time Nanoparticle Monitoring Instruments in the Workplaces

Ham, Seunghon,Lee, Naroo,Eom, Igchun,Lee, Byoungcheun,Tsai, Perng-Jy,Lee, Kiyoung,Yoon, Chungsik Occupational Safety and Health Research Institute 2016 Safety and health at work Vol.7 No.4

Background: Relationships among portable scanning mobility particle sizer (P-SMPS), condensation particle counter (CPC), and surface area monitor (SAM), which are different metric measurement devices, were investigated, and two widely used research grade (RG)-SMPSs were compared to harmonize the measurement protocols. Methods: Pearson correlation analysis was performed to compare the relation between P-SMPS, CPC, and SAM and two common RG-SMPS. Results: For laboratory and engineered nanoparticle (ENP) workplaces, correlation among devices showed good relationships. Correlation among devices was fair in unintended nanoparticle (UNP)-emitting workplaces. This is partly explained by the fact that shape of particles was not spherical, although calibration of sampling instruments was performed using spherical particles and the concentration was very high at the UNP workplaces to allow them to aggregate more easily. Chain-like particles were found by scanning electron microscope in UNP workplaces. The CPC or SAM could be used as an alternative instrument instead of SMPS at the ENP-handling workplaces. At the UNP workplaces, where concentration is high, real-time instruments should be used with caution. There are significant differences between the two SMPSs tested. TSI SMPS showed about 20% higher concentration than the Grimm SMPS in all workplaces. Conclusions: For nanoparticle measurement, CPC and SAM might be useful to find source of emission at laboratory and ENP workplaces instead of P-SMPS in the first stage. An SMPS is required to measure with high accuracy. Caution is necessary when comparing data from different nanoparticle measurement devices and RG-SMPSs.

소방 실화재 훈련 중 발생하는 미세먼지와 호흡성분진의 특성

함승헌(Seunghon Ham),최신웅(Sin-Woong Choi),오동진(Dongjin Oh) 국립소방연구원 2021 소방안전연구 Vol.2 No.1

실화재 훈련장에서 훈련교관이 훈련 전과 후에 수행하는 업무에 대하여 미세먼지, 호흡성분진에 대하여 노출평가를 실시하였고, 그 결과 미세먼지와 호흡성분진에 노출이 되는 것을 알 수 있었다. 개선 방향으로는 훈련 후 발생한 재를 삽으로 정리할 경우 분진이 비산되기 때문에 삽으로 정리하는 작업을 진공청소기를 이용하여 재를 흡입할 수 있도록 개선이 필요하고, 습식 작업도 노출을 저감하는데 효과적이다. 또한 개선이 되기 전 까지는 반드시 적절한 보호구를 지급하여 착용할 수 있도록 해야 한다. Exposure assessment was conducted for particulate matter (PM) and respirable dust before and after live fire training. Exposure to PM and respirable dust was found. Regarding the improvement of the training environment, since dust is released when the ash generated after training is cleaned with a shovel, it is necessary to improve the shovel cleaning operation so that the ash can be inhaled using a vacuum cleaner. Wet work is also effective in reducing exposure. Additionally, until improvement is obtained, appropriate protective equipment must be provided.

항공기 내 실내공기질에 관한 고찰: 이동의 증가와 건강에 미치는 영향 및 블리드에어의 영향

함승헌(Seunghon Ham) 한국환경보건학회 2023 한국환경보건학회지 Vol.49 No.3

Background: With the rise in global mobility, aircraft indoor air quality has become a significant public health concern. This study focuses on the health implications of increased travel and bleed air—air drawn from aircraft engines for cabin pressurization and air conditioning. Objectives: This research aims to review the potential health effects related to exposure to aircraft cabin air, particularly the effects of bleed air during fume events. Methods: We conducted a literature review of existing studies on aircraft cabin air quality. We focused on both the immediate and health effects of exposure to cabin air, particularly those related to bleed air contaminants. Results: The review found a possible link between exposure to aircraft cabin air and certain health issues, especially in cabin crew and frequent flyers. There was an increased incidence of respiratory and neurological symptoms related to bleed air exposure. However, the cumulative health effects of frequent air travel remain inconclusive due to limited data. Conclusions: This study highlights the need for improving air quality in aircraft to protect public health. While further research is needed to understand the cumulative effects of frequent air travel, the reduction of exposure to bleed air contaminants should be a priority. These findings underline the need for regulatory changes and technological improvements in aircraft cabin air quality.

Spatial–Temporal Dispersion of Aerosolized Nanoparticles During the Use of Consumer Spray Products and Estimates of Inhalation Exposure

Park, Jihoon,Ham, Seunghon,Jang, Miyeon,Lee, Jinho,Kim, Sunju,Kim, Sungkyoon,Lee, Kiyoung,Park, Donguk,Kwon, Jungtaek,Kim, Hyunmi,Kim, Pilje,Choi, Kyunghee,Yoon, Chungsik American Chemical Society 2017 Environmental science & technology Vol.51 No.13

<P>We evaluated the spatial-temporal dispersion of airborne nanomaterials during the use of spray consumer products and estimated the level of consumer inhalation exposure. A total of eight spray products including five propellant and three pump types were selected to evaluate the dispersion of airborne nanoparticles across time and space in a cleanroom which could control the background particles. Four products were advertised to contain silver and one contained titanium nanoparticles, while three products were specified no ENM but as being manufactured through the use of nanotechnology. We used direct-reading instruments with a thermodesorber unit to measure the particles (number, mass, surface area), as well as filter sampling to examine physicochemical characteristics. Sampling was conducted simultaneously at each location (1 m, near-field; 2, 3 m, far-field) by distance from the source. We estimated the inhaled doses at the breathing zone, and the doses deposited in each part of the respiratory tract using the experimental data and mathematical models. Nanoparticles released from the propellant sprays persisted in the air and dispersed over a large distance due to their small size (1466–5565 particles/cm<SUP>3</SUP>). Conversely, the pump sprays produced larger droplets that settled out of the air relatively close to the source, so the concentration was similar to background level (<200 particles/cm<SUP>3</SUP>). The estimates of inhalation exposure also suggested that exposure to nanoparticles was greater with propellant sprays (1.2 × 10<SUP>8</SUP> ± 4.0 × 10<SUP>7</SUP> particles/kgbw/day) than pump sprays (2.7 × 10<SUP>7</SUP> ± 6.5 × 10<SUP>6</SUP> particles/kgbw/day). We concluded that the propellant sprays create a higher risk of exposure than the pump sprays.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/esthag/2017/esthag.2017.51.issue-13/acs.est.7b00211/production/images/medium/es-2017-00211d_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/es7b00211'>ACS Electronic Supporting Info</A></P>

Prevalence of Asthma in Children in worldwide and Korea

Gyuseok Hwang,Seunghon Ham,Chungsik Yoon 서울대학교 보건환경연구소 2018 보건학논집 Vol.55 No.1

Objectives: Asthma in children has been worldwide disease and lots of research has been conducted for etiology, prevalence and prevention strategy. Most prevalence studies were limited to the specific area, countries, time or some period so that they could only give snap shot of target study population in a given time. The purpose of this study was to review the temporal trend of the prevalence of asthma in children in worldwide and Korea. Methods: Articles related to the prevalence of asthma or asthmatic symptoms in children, written in English or Korean, were systematically searched using web searching engine. Then, the prevalence rates were described by countries with study design and criteria of asthma diagnosis while in Korea residence area of target population was used instead of country. Results: The prevalence rates were varied by the diagnostic criteria of asthma. So, the prevalence of parent reported asthma or wheezing symptoms were higher than that of physician diagnostic asthma (PDA). The prevalence of asthma worldwide has continually increased since 1970 to the late 1990 or 2000. It was 5%, 8.3±6.5%, 13.8±11.1%, 11.4±8.3% in 1970’, 1980’, 1990’, after 2000’, respectively. After 2000’, the trend of the prevalence of asthma seemed to be equilibrium or slightly increased but it is unclear because of variation of data. In Korean, PDA has not changed dramatically but small fluctuation over the decades. The PDA asthma was 8.9 ± 2.8%, 6.0 ±2.9%, and 8.9 ±2.7% in 1980, 1990 and 2000, respectively. Conclusion: The prevalence rate of asthma worldwide has increased over decades but the increasing rate became unclear after 2000’ while it was steadily continued over decades since 1980’.

Characterization and Control of Nanoparticle Emission during 3D Printing

Kwon, Ohhun,Yoon, Chungsik,Ham, Seunghon,Park, Jihoon,Lee, Jinho,Yoo, Danbi,Kim, Yoojin American Chemical Society 2017 Environmental science & technology Vol.51 No.18

<P>This study aimed to evaluate particle emission characteristics and to evaluate several control methods used to reduce particle emissions during three-dimensional (3D) printing. Experiments for particle characterization were conducted to measure particle number concentrations, emission rates, morphology, and chemical compositions under manufacturer-recommended and consistent-temperature conditions with seven different thermoplastic materials in an exposure chamber. Eight different combinations of the different control methods were tested, including an enclosure, an extruder suction fan, an enclosure ventilation fan, and several types of filter media. We classified the thermoplastic materials as high emitter (> 10(11) #/min), medium emitters (10(9) #/min -10(11) #/min), and low emitters (< 10(9) #/min) based on nanoparticle emissions. The nanoparticle emission rate was at least 1 order of magnitude higher for all seven filaments at the higher consistent extruder temperature than at the lower manufacturer-recommended temperature. Among the eight control methods tested, the enclosure with a high-efficiency particulate air (HEPA) filter had the highest removal effectiveness (99.95%) of nanoparticles. Our recommendations for reducing particle emissions include applying a low temperature, using low-emitting materials, and instituting control measures like using an enclosure around the printer in conjunction with an appropriate filter (e.g., HEPA filter) during 3D printing.</P>