Factors affecting interpretation of national biomonitoring data from multiple countries: BPA as a case study.

INTRODUCTION: The use of biomonitoring data as an indicator of national levels of human exposure to environmental chemicals has grown in importance and prevalence. Nationally representative urinary bisphenol A (BPA) data are now available for Canada, the United States and Korea. Here we address the following questions: Are urinary BPA data from these countries comparable? What can be discerned regarding geographic and/or temporal similarities or differences? Are there generalizable lessons to be learned regarding comparison of biomonitoring results from different countries? METHODS: We examined underlying methods and resultant urinary BPA data from national surveys of three countries: Canada (Canadian Health Measures Survey, CHMS, 2009-2015); United States (National Health and Nutrition Examination Survey, NHANES, 2009-2014); and Korea (Korean National Environmental Health Survey, KoNEHS, 2009-2014). We estimated BPA daily intakes on both a volume- and creatinine-adjusted basis. RESULTS: The three countries use similar methods for analyzing urine samples for BPA and participate in external proficiency testing with acceptable results. Field blanks are only used in the CHMS program. There were program-specific differences in fasting times of participants. Median urinary BPA levels in Canada remained relatively constant over the three cycles (1.1-1.2 ng/ml), while US levels decreased (from 1.9 to 1.3 ng/ml) and Korean levels increased (from 0.7 to 1.1 ng/ml) over similar time periods. The most recent survey year data indicate that levels do not differ substantially across countries. Canadian urinary BPA levels have been stable; the subtle, non-significant decrease in intakes may be due to higher body weight in the more recent Canadian surveys. In contrast, the decrease in intakes in the US appears to be due to decreases in urinary BPA as body weights in the US have been stable. Estimated 95th percentile intakes are over an order of magnitude below current health-based guidance values. DISCUSSION: Our assessment of urinary BPA data from Canada, the US and Korea indicates that methodological differences, methods for dilution adjustment, and population characteristics should be carefully considered when interpreting biomonitoring data. Despite the plethora of publications describing issues with use of creatinine levels for urinary dilution adjustment, there have been no major methodological advances that would assist in interpreting urinary chemical data. A combination of biomonitoring and traditional exposure assessment approaches may be needed to fully assess human exposures to BPA and other chemicals. CONCLUSIONS: National biomonitoring surveys provide important information on population levels of chemicals such as BPA and can assist in understanding temporal and geographic similarities, differences, and trends. However, caution must be exercised when using these data to draw anything but broad conclusions, due to both intercountry methodological differences and factors affecting urinary chemical levels that are still poorly understood. While the issues raised in this paper do not appear to be a major concern specifically for the national-scale monitoring of BPA described here, they must be considered when comparing data for other chemicals measured as part of both national and smaller-scale biomonitoring-based research as well as for BPA data from other studies.

The interactive association of smoking and drinking levels with presence of periodontitis in South Korean adults.

BACKGROUND: Periodontitis is a chronic and long-lasting low-grade inflammatory disease. Numerous studies have shown that the severity of periodontitis rose when there was an increase in the amount of smoking or alcohol consumption. However, as periodontitis known as a chronic disease, it is important to consider not only the amount but "duration" with frequency i.e., rates, of smoking or drinking. This study assessed impacts of the amount and duration of smoking and drinking on periodontal health in Korean adults. We also investigated whether or not there is an interactive effect of smoking and drinking on periodontal health. METHODS: Under a cross-sectional study design, we used data from the fourth and fifth the Korean National Health and Nutrition Examination Survey (KNHANES) sessions (2008-2010). A total of 18,488 subjects (over 19 years) answered both smoking and drinking status and were given the periodontal examination. Periodontal health status was determined by the community periodontal index (CPI) developed by the World Health Organization (WHO). According to the WHO guidelines, if a participant's CPI was 3 or larger, we classified the person as a case of periodontitis. Participants with a CPI < 3 were assigned to the control group. RESULTS: Prevalence of periodontitis for self-reported smokers or drinkers in South Korea was 35.0 or 28.0 %, respectively. We observed 1.20 (0.93~1.56) of odds ratio (95 % CI) for prevalence (POR) of periodontitis for those smoked <13 pack-year (PY) and drank ≥6.8 glass-year (GY). And we had POR of 1.91 (1.34~2.73) for those smoked ≥13 PY and drank <6.8 GY, compared to those nonsmoking nondrinkers. The observed POR of 2.41 (95 % CI: 1.94-3.00), for those smoked ≥13 PY and drank ≥6.8 GY, was higher than a multiplicative effect estimated, i.e., 1.20 (0.93~1.56) [those smoked <13 PY and drank ≥6.8 GY] × 1.91 (1.34~2.73) [those smoked ≥13 PY and drank <6.8 GY], or 2.29. CONCLUSIONS: We observed a multiplicative interactive effect of smoking and drinking on periodontal status among Korean adults.

Optimum cutoff value of urinary cotinine distinguishing South Korean adult smokers from nonsmokers using data from the KNHANES (2008-2010).

INTRODUCTION: Cutoff values for distinguishing smokers from nonsmokers have generally been derived from studies in White populations. Even though recent population-based studies have demonstrated that cutoff values can differ by race and ethnicity, few studies have explored cutoff values among Asian populations. We established the cutoff values for urinary cotinine and cotinine:creatinine ratio (CCR) using a nationally representative South Korean adult population sample. METHODS: Data were obtained from the Korea National Health and Nutrition Examination Survey (KNHANES) 2008-2010 with pooled sampling weights. Adult participants (n = 11,629) aged ≥19 were included. Optimal cutoff values were determined by performing receiver operating characteristic curve analysis. RESULTS: The optimum cutoff values for urinary cotinine and CCR for Korean adults were found to be 164ng/mL and 1122ng/mg, respectively. The application of these urinary cotinine and CCR cutoff values for the female subpopulations aged 19-34, 35-54, and ≥55 years provided sensitivities ranging from 87.1% to 93.8% and from 82.9% to 94.9%, respectively, while maintaining specificity of ≥92%. For the 3 male age-based subpopulations, we obtained sensitivities and specificities for cotinine ranging from 93.1% to 94.5% and from 92.8% to 97.0%, respectively, and for CCR ranging from 90.0% to 96.9% and from 92.2% to 96.8%, respectively. CONCLUSIONS: Our cutoff values should allow researchers conducting environmental epidemiological or clinical studies in South Korea to distinguish adult smokers from nonsmokers effectively. However, different values may be applicable for subpopulations with different smoking prevalence rates or higher exposure levels to secondhand smoke.

Assessing secondhand smoke using biological markers.

Secondhand smoke exposure (SHSe) is a known cause of many adverse health effects in adults and children. Increasingly, SHSe assessment is an element of tobacco control research and implementation worldwide. In spite of decades of development of approaches to assess SHSe, there are still unresolved methodological issues; therefore, a multidisciplinary expert meeting was held to catalogue the approaches to assess SHSe and with the goal of providing a set of uniform methods for future use by investigators and thereby facilitate comparisons of findings across studies. The meeting, held at Johns Hopkins, in Baltimore, Maryland, USA, was supported by the Flight Attendant Medical Research Institute (FAMRI). A series of articles were developed to summarise what is known about self-reported, environmental and biological SHSe measurements. Non-smokers inhale toxicants in SHS, which are mainly products of combustion of organic materials and are not specific to tobacco smoke exposure. Biomarkers specific to SHSe are nicotine and its metabolites (e.g., cotinine), and metabolites of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). Cotinine is the preferred blood, saliva and urine biomarker for SHSe. Cotinine and nicotine can also be measured in hair and toenails. NNAL (4-[methylnitrosamino]-1-[3-pyridyl]-1-butanol), a metabolite of NNK, can be determined in the urine of SHS-exposed non-smokers. The selection of a particular biomarker of SHSe and the analytic biological medium depends on the scientific or public health question of interest, study design and setting, subjects, and funding. This manuscript summarises the scientific evidence on the use of biomarkers to measure SHSe, analytical methods, biological matrices and their interpretation.

Comparison of Personal or Indoor PM2.5 Exposure Level to That of Outdoor: Over Four Seasons in Selected Urban, Industrial, and Rural Areas of South Korea: (K-IOP Study).

This study aimed to compare the distribution of indoor, outdoor, and personal PM2.5 (particulate matter ≤ 2.5 µm) hourly concentrations measured simultaneously among 81 nonsmoking elderly participants (65 years or older) living in urban, industrial, or rural areas over 4 seasons (2 weeks per season) from November 2021 to July 2022). PM2.5 measurements were conducted using low-cost sensors with quality control and quality assurance tests. Seasonal outdoor PM2.5 levels were 16.4 (9.1-29.6) µg/m3, 20.5 (13.0-38.0) µg/m3, 18.2 (10.2-31.8) µg/m3, and 9.5 (3.8-18.7) µg/m3 for fall, winter, spring, and summer, respectively. For indoor PM2.5, the median seasonal range was 5.9-7.5 µg/m3, and the median personal PM2.5 exposure concentration was 8.0-9.4 µg/m3. This study provided seasonal distributions of IO (ratio of indoor to outdoor PM2.5 concentration) and PO (ratio of personal to outdoor PM2.5 concentration) using a total of 94,676 paired data points. The median seasonal IO ranged from 0.30 to 0.51 in fall, winter, and spring; its value of summer was 0.70. The median PO by season and study area were close to 1.0 in summer while it ranged 0.5 to 0.7 in other seasons, statistically significantly lower (p < 0.05) than that in summer. Our study has revealed that the real-world exposure level to PM2.5 among our elderly study participants might be lower than what was initially expected based on the outdoor data for most of the time. Further investigation may need to identify the reasons for the discrepancy, personal behavior patterns, and the effectiveness of any indoor air quality control system.

JUUL preference among Korean adult tobacco users and its effect on attempts to quit tobacco: A follow-up survey four months post JUUL launch.

INTRODUCTION: This study examined the various factors in the selection of JUUL (and/or), a pod-mod type electronic cigarette (EC), and the changes in EC patterns before and after the JUUL debut on 24 May 2019, using follow-up survey data of adult tobacco users in South Korea. METHODS: This study examined transition outcomes among tobacco users and factors associated with future JUUL use. Convenience sample data were collected from adult tobacco users in South Korea, from March-April 2019 (baseline, n=2173) to September 2019 (follow-up, n=779). Results were obtained from the 779 respondents in the follow-up survey, and user data of one or more tobacco products were analyzed. The changes in the proportion of EC and JUUL use during this period were calculated, and multivariate logistic regression analysis was conducted to investigate the selection factors of JUUL. RESULTS: Four months after the JUUL launch, the proportion of current EC and JUUL users among the whole sample increased by 10.3% (42.6-52.9%, p<0.001) and 17.7 % (4.0-21.7%, p<0.001), respectively, while the proportion of triple users doubled (18.7% vs 37.5%, p<0.001). Among current EC users, the percentage of quitting EC within one month decreased from 18.7% to 8.7%; this change was more pronounced among concurrent JUUL users than non-JUUL users (p<0.001). In the multivariate logistic analysis with adjustment for possible confounders, JUUL use was significantly associated with male sex, young and middle age, and metropolitan residency status at the baseline survey. CONCLUSIONS: After the launch of JUUL in South Korea, EC users, including JUUL and triple users, increased significantly, but the intention to stop EC decreased significantly. Given the serious interests of the tobacco industry in these products, additional regulation is warranted.

Urinary Phthalate Metabolites and Slow Walking Speed in the Korean Elderly Environmental Panel II Study.

BACKGROUND: Previous epidemiological studies have suggested that phthalate exposure may contribute to neurocognitive and neurobehavioral disorders and decreased muscle strength and bone mass, all of which may be associated with reduced physical performance. Walking speed is a reliable assessment tool for measuring physical performance in adults age 60 y and older. OBJECTIVE: We investigated associations between urinary phthalate metabolites and slowness of walking speed in community-dwelling adults ages 60-98 y. METHODS: We analyzed 1,190 older adults [range, 60-98 y of age; mean±standard deviation (SD) , 74.81±5.99] from the Korean Elderly Environmental Panel II study and measured repeatedly up to three times between 2012 and 2014. Phthalate exposure was estimated using the following phthalate metabolites in urine samples: mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP), mono-n-butyl phthalate (MnBP), mono-(2-ethyl-5-carboxypentyl) phthalate (MECPP), and mono-benzyl phthalate (MBzP). Slowness was defined as a walking speed of <1.0meter/second. We used logistic and linear regression models to evaluate the association between each urinary phthalate metabolite and slowness or walking-speed change. We also used Bayesian kernel machine regression (BKMR) to examine overall mixture effects on walking speed. RESULTS: At enrollment, MBzP levels were associated with an increased odds of slowness [odds ratio (OR) per doubling increase: 1.15, 95% confidence interval (CI): 1.02, 1.30; OR for the highest vs. lowest quartile: 2.20 (95% CI: 1.12, 4.35) with p-trend across quartiles=0.031]. In longitudinal analyses, MEHHP levels showed an increased risk of slowness [OR per doubling increase: 1.15 (95% CI: 1.02, 1.29), OR for the highest vs. lowest quartile: 1.47 (95% CI: 1.04, 2.06), p- trend=0.035]; whereas those with higher MnBP showed a reduced risk of slowness [OR per doubling increase: 0.84 (95% CI: 0.74, 0.96), OR in the highest (vs. lowest) quartile: 0.64 (95% CI: 0.47, 0.87), p-trend=0.006]. For linear regression models, MBzP quartiles were associated with slower walking speed (p-trend=0.048) at enrollment, whereas MEHHP quartiles were associated with slower walking speed, and MnBP quartiles were associated with faster walking speed in longitudinal analysis (p-trend=0.026 and <0.001, respectively). Further, the BKMR analysis revealed negative overall trends between the phthalate metabolite mixtures and walking speed and DEHP group (MEHHP, MEOHP, and MECPP) had the main effect of the overall mixture. DISCUSSION: Urinary concentrations of prevalent phthalates exhibited significant associations with slow walking speed in adults ages 60-98 y. https://doi.org/10.1289/EHP10549.

Racial differences in hair nicotine concentrations among smokers.

INTRODUCTION: In the United States, race/ethnicity is a strong determinant of tobacco use patterns, biomarkers of tobacco smoke components and metabolites, and likelihood of successful cessation. Although Black smokers tend to smoke fewer cigarettes than White smokers, they have higher cotinine levels and disease risk and lower cessation success. We examined racial differences in hair nicotine concentrations among daily tobacco smokers (n = 103) in Baltimore, Maryland. METHODS: Participants completed a survey, and hair samples were collected and analyzed for nicotine concentration using gas chromatography coupled with mass spectrometry. RESULTS: After adjustment, hair nicotine concentrations among Black smokers were more than 5 times higher than among White smokers (95% CI 3.0, 10.5). Smokers reporting hair treatments other than coloring (bleaching, permanent, or straightening) in the past 12 months had 66% lower (95% CI 32%, 83%) hair nicotine concentrations. Smokers reporting smoking their first cigarette within 30 min of waking had twice the hair nicotine concentrations of those whose time to first cigarette was greater than 30 min after waking (95% CI 1.1, 4.2). For every additional cigarette smoked per day up to 20, mean hair nicotine concentration among all smokers increased by 4% (95% CI -1%, 9%). CONCLUSIONS: This study demonstrates that Black smokers have substantially higher hair nicotine levels than White smokers, after controlling for cigarettes smoked per day and other exposure sources. Time to first cigarette, cigarettes smoked per day, and use of hair treatments other than coloring were also associated with hair nicotine concentrations among smokers.

Winter season temperature drops and sulfur dioxide levels affect on exacerbation of refractory asthma in South Korea: a time-trend controlled case-crossover study using soonchunhyang asthma cohort data.

OBJECTIVE: According to the American Thoracic Society, approximately 5% of all asthmatics have refractory asthma (RA); these patients fail to recover lost lung function even after long-term treatment with high doses of medications. METHODS: Using a time-trend controlled case-crossover study design, we calculated odds ratios to evaluate whether exposure to ambient air pollutants and certain meteorological conditions on the day of admission (Lag 0) and up to 3 days before admission (Lag1 through Lag 3) were associated with acute RA exacerbation. Results were obtained after controlling for the effects of seasonality, smoking, and allergen sensitivity; we stratified our data into four seasons with respect to the median temperature of each month and further stratified them according to self-reported smoking status and skin-prick test results. RESULTS: In our study, RA patients (n = 82), living in metropolitan city of Seoul and Kyunggi Province, accounted for 3.7% of all asthmatics (n = 2298) registered in our asthma cohort between 2005 and 2009. In winter, a 1°C decrease in ambient temperature and a 1 ppb increase in sulfur dioxide concentration on the day of Lag 1 were associated with 14.8% (95% confidence interval [CI]: 0.9-26.7) and 19.7% (95% CI: 3.3-38.7) increases in the risk of RA exacerbation among nonsmokers, respectively. Similar associations were obtained on the day of Lag 2. The association remained unchanged after excluding patients sensitive to Dermatophagoides farinae and Dermatophagoides pteronyssinus. CONCLUSIONS: Exposure to temperature drops and increased sulfur dioxide concentrations are positively associated with the occurrence of acute RA exacerbation during winter with 1 or 2 day lags.

Perceived relative harm of heated tobacco products and electronic cigarettes and its association with use in smoke-free places: A cross-sectional analysis of Korean adults.

INTRODUCTION: Electronic cigarettes (e-cigarettes) and heated tobacco products (HTPs) are often considered to be less harmful and safer than combustible cigarettes (CCs). As a result, numerous tobacco product users opt to use e-cigarettes or HTPs as a safer alternative, though the safety of these products is not fully warranted. The present study aimed to assess the various attitudes towards e-cigarettes and/or HTPs among Korean tobacco product users and their associations with the practical use of e-cigarettes and/or HTPs in private or smoke-free public places. METHODS: A cross-sectional study using self-administered questionnaires was conducted from March 2019 to July 2019 on 2971 adult tobacco product users. Attitude towards e-cigarettes and/or HTPs, as well as the relative harm perceptions, in association with their practical use in private or smoke-free areas, were also analyzed. RESULTS: Among those surveyed, 46.8% were exclusive users (CC-only smokers 23.5%, e-cigarette-only users 10.7%, HTP-only users 12.7%), and 47.6% were poly-users. Compared with non-e-cigarette or non-HTP users, current e-cigarette or HTP users perceived e-cigarettes or HTPs as less harmful than CCs and they were more acceptable to e-cigarettes or HTPs being used indoors. Their positive attitudes were associated with their more frequent use at home or in their car. Less number of participants supported that the government should regulate e-cigarettes or HTPs in the same way as CCs, their attitude being associated with more frequent use in smoke-free public places. CONCLUSIONS: E-cigarettes or HTPs users have more positive attitudes toward their tobacco products than non-e-cigarette or non-HTP users. Those with more positive attitudes toward e-cigarettes or HTPs are closely related to their use in smoke-free places.

Predicting Health Risks of Adult Asthmatics Susceptible to Indoor Air Quality Using Improved Logistic and Quantile Regression Models.

The increasing global patterns for asthma disease and its associated fiscal burden to healthcare systems demand a change to healthcare processes and the way asthma risks are managed. Patient-centered health care systems equipped with advanced sensing technologies can empower patients to participate actively in their health risk control, which results in improving health outcomes. Despite having data analytics gradually emerging in health care, the path to well established and successful data driven health care services exhibit some limitations. Low accuracy of existing predictive models causes misclassification and needs improvement. In addition, lack of guidance and explanation of the reasons of a prediction leads to unsuccessful interventions. This paper proposes a modeling framework for an asthma risk management system in which the contributions are three fold: First, the framework uses a deep learning technique to improve the performance of logistic regression classification models. Second, it implements a variable sliding window method considering spatio-temporal properties of the data, which improves the quality of quantile regression models. Lastly, it provides a guidance on how to use the outcomes of the two predictive models in practice. To promote the application of predictive modeling, we present a use case that illustrates the life cycle of the proposed framework. The performance of our proposed framework was extensively evaluated using real datasets in which results showed improvement in the model classification accuracy, approximately 11.5-18.4% in the improved logistic regression classification model and confirmed low relative errors ranging from 0.018 to 0.160 in quantile regression model.

Household insecticide use and urinary 3-phenoxybenzoic acid levels in an elder population: a repeated measures data.

BACKGROUND: Pyrethroids are associated with adverse health consequences, even at low-dose exposures. However, there is limited evidence on pyrethroids exposure levels among vulnerable elder population and on their exposure sources. OBJECTIVE: We tried to determine pyrethroids exposure levels among Korean elders and their exposure sources. METHODS: We measured levels of 3-phenoxybenzoic acid (3-PBA), a pyrethroids metabolite, in urines repeatedly collected from 1239 Korean rural and urban elders; we also explored exposure sources for pyrethroids using questionnaire data. RESULTS: Our participants had high levels of 3-PBA with 446 (36.0%) of elders with 3-PBA level over 2 ng/mL of 95th percentile of the German representative populations. After adjustment for sex, age, smoking status, visit episode, and surveyed season using linear mixed effect models, household insecticide spray use was significantly associated with 3-PBA level (ß = 0.03 and p = 0.02) and the association was apparent only for females (ß = 0.03 and p = 0.03). In the analyses for nonlinear relationships using generalized additive mixed models, there was a J-shape change in 3-PBA level by insecticide spray use (p < 0.01 both in total population and in females). SIGNIFICANCE: Household insecticide spray was a predominant exposure source for pyrethroids at community level among Korean elders, warning more stringent control for frequently exposed environmental factors for pyrethroids including insecticide spray.

Comparison of Nicotine Dependence and Biomarker Levels among Traditional Cigarette, Heat-Not-Burn Cigarette, and Liquid E-Cigarette Users: Results from the Think Study.

This study aimed to compare Korean smokers' smoking-related biomarker levels by tobacco product type, including heat-not-burn cigarettes (HNBC), liquid e-cigarettes (EC), and traditional cigarettes (TC). Nicotine dependence levels were evaluated in Korean adult study participants including TC-, EC-, HNBC-only users and nonsmokers (n = 1586) from March 2019 to July 2019 in Seoul and Cheonan/Asan South Korea using the Fagerström Test Score. Additionally, urine samples (n = 832) were collected for the measurement of urinary nicotine, cotinine, OH-cotinine, NNAL(4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol), CYMA(N-acetyl-S-(2-cyanoehtyl)-L-cysteine), or CEMA (2-cyanoethylmercapturic acid) using LC-MS/MS. The median(interquartile range) nicotine dependence level was not different among the three types of smokers, being 3.0 (2.0-5.0) for TC- (n = 726), 3.0 (1.0-4.0) for EC- (n = 316), and 3.0 (2.0-4.0) for HNBC- (n = 377) only users. HNBC-only users presented similar biomarker levels compared to TC-only users, except for NNAL (HNBC: 14.5 (4.0-58.8) pg/mL, TC: 32.0 (4.0-69.6) pg/mL; p = 0.0106) and CEMA (HNBC: 60.4 (10.0-232.0) ng/mL, TC: 166.1 (25.3-532.1) ng/mL; p = 0.0007). TC and HNBC users showed increased urinary cotinine levels as early as the time after the first smoke of the day. EC users' biomarker levels were possibly lower than TC or HNBC users' but higher than those of non-smokers.

Performance improvement of machine learning techniques predicting the association of exacerbation of peak expiratory flow ratio with short term exposure level to indoor air quality using adult asthmatics clustered data.

Large-scale data sources, remote sensing technologies, and superior computing power have tremendously benefitted to environmental health study. Recently, various machine-learning algorithms were introduced to provide mechanistic insights about the heterogeneity of clustered data pertaining to the symptoms of each asthma patient and potential environmental risk factors. However, there is limited information on the performance of these machine learning tools. In this study, we compared the performance of ten machine-learning techniques. Using an advanced method of imbalanced sampling (IS), we improved the performance of nine conventional machine learning techniques predicting the association between exposure level to indoor air quality and change in patients' peak expiratory flow rate (PEFR). We then proposed a deep learning method of transfer learning (TL) for further improvement in prediction accuracy. Our selected final prediction techniques (TL1_IS or TL2-IS) achieved a balanced accuracy median (interquartile range) of 66(56~76) % for TL1_IS and 68(63~78) % for TL2_IS. Precision levels for TL1_IS and TL2_IS were 68(62~72) % and 66(62~69) % while sensitivity levels were 58(50~67) % and 59(51~80) % from 25 patients which were approximately 1.08 (accuracy, precision) to 1.28 (sensitivity) times increased in terms of performance outcomes, compared to NN_IS. Our results indicate that the transfer machine learning technique with imbalanced sampling is a powerful tool to predict the change in PEFR due to exposure to indoor air including the concentration of particulate matter of 2.5 µm and carbon dioxide. This modeling technique is even applicable with small-sized or imbalanced dataset, which represents a personalized, real-world setting.

Exposure to particulate matters (PM2.5) and airborne nicotine in computer game rooms after implementation of smoke-free legislation in South Korea.

INTRODUCTION: In South Korea, computer game rooms are subject to regulations mandating a designated nonsmoking area pursuant to Article 7 of the Enforcement Rules of the National Health Promotion Act; nonsmoking areas must be enclosed on all sides by solid and impermeable partitions. METHODS: Using PM(2.5) monitors (SidePak AM510) and airborne nicotine monitors, we measured concentrations in smoking and nonsmoking areas to examine whether separation of the nonsmoking areas as currently practiced is a viable way to protect the nonsmoking area from secondhand smoke exposure. Convenient samplings were conducted at 28 computer game rooms randomly selected from 14 districts in Seoul, South Korea between August and September 2009. RESULTS: The medians (interquartile range) of PM(2.5) concentrations in smoking and nonsmoking areas were 69.3 µg/m(3) (34.5-116.5 µg/m(3)) and 34 µg/m(3) (15.0-57.0 µg/m(3)), while those of airborne nicotine were 0.41 µg/m(3) (0.25-0.69 µg/m(3)) and 0.12 µg/m(3) (0.06-0.16 µg/m(3)), respectively. Concentrations of airborne nicotine and PM(2.5) in nonsmoking areas were substantially positively associated with those in smoking areas. The Spearman correlation coefficients for them were 0.68 (p = .02) and 0.1 (p = 0.7), respectively. According to our modeling result, unit increase of airborne nicotine concentration in a smoking area contributed to 7 (95% CI = 2.5-19.8) times increase of the concentration in the adjacent nonsmoking area after controlling for the degree of partition left closed and the indoor space volume. CONCLUSIONS: Our study thus provides evidence for the introduction of more rigorous policy initiatives aimed at encouraging a complete smoking ban in such venues.

Machine Learning-Based Activity Pattern Classification Using Personal PM2.5 Exposure Information.

The activity pattern is a significant factor in identifying hotspots of personal exposure to air pollutants, such as PM2.5. However, the recording process of an activity pattern can be annoying to study participants, because they are often asked to bring a diary or a tracking recorder to write or validate their activity patterns when they change their activity profiles. Furthermore, the accuracy of the records of activity patterns can be lower, because people can mistakenly record them. Thus, this paper proposes an idea to overcome these problems and make the whole data-collection process easier and more reliable. Our idea was based on transforming training data using the statistical properties of the children's personal exposure level to PM2.5, temperature, and relative humidity and applying the properties to a decision tree algorithm for classification of activity patterns. From our final machine-learning modeling processes, we observed that the accuracy for activity-pattern classification was more than 90% in both the training and test data. We believe that our methodology can be used effectively in data-collection tasks and alleviate the annoyance that study participants may feel.

Are Heated Tobacco Product Users Less Likely to Quit than Cigarette Smokers? Findings from THINK (Tobacco and Health IN Korea) Study.

Since the advent of heated tobacco products in June 2017 in South Korea, the sale of heated tobacco products accounted for 10.5% of total tobacco sales in 2019. However, the decreasing trend in total tobacco sales is gradually weakening and the number of visitors using stop smoking services has also dropped. This study examines the association between the use of new tobacco products and related products and cessation behaviors. A cross-sectional study using a self-administered questionnaire was conducted from March 2019 to July 2019 for 2831 adult tobacco users. The difference in rates of quit attempts using the type of tobacco products and related products in the past year were noted (55.6% (any cigarette smoker), 46.7% (any e-cigarette user), and 39.6% (any heated tobacco product user)). About a 30% increase in quit attempts was observed for the triple users of either conventional cigarette or heated tobacco product than exclusive users. Exclusive heated tobacco product and e-cigarette users were approximately 40% and 20% less likely to quit the product they used than exclusive cigarette smokers, respectively. These findings can explain recent occurrences in South Korea, such as the reduction of visitors at smoking cessation clinics and the attenuation of the decline in tobacco sales.

Indoor and outdoor PM2.5 exposure, and anxiety among schoolchildren in Korea: a panel study.

This panel study aimed to evaluate the associations between short-term exposure to indoor and outdoor PM2.5 and anxiety in schoolchildren. During 3 waves in March, July, and November 2018 with 7 days per wave, 52 children aged 10 years were recruited from two schools in a city in Korea. To assess outdoor exposure, we used PM2.5 concentration measures for every hour at the national measurement station (NMS) closest to the two participating schools. To assess indoor exposure, we measured PM2.5 concentration at the children's homes and in classrooms, based on 30-min average. Based on time-activity logs, personal average daily exposure values were calculated for each participant, according to exposure values assessed at 30-min intervals by location. Children's anxiety was assessed via the Korean version of the State Anxiety Inventory for children every day during each wave. Linear mixed effects model was conducted to analyze the association between PM2.5 exposure and anxiety using repeated measurements. Personal exposure to PM2.5 by time-activity log was the highest in March and at home. A low correlation coefficient was observed between PM2.5 concentrations at home and at the NMS (ρ = 0.36, p < 0.0001) whereas a high correlation coefficient was observed between PM2.5 concentrations in classrooms and at the NMS (ρ = 0.64, p < 0.0001). There was no association between PM2.5 exposure and anxiety in children based on the analysis of repeated measurements during the study period. Since previous studies reported controversial results, long-term follow-up studies are needed in various regions to further investigate the associations between PM2.5 exposure and children's mental health.

Effects of Indoor Air Purifiers on Children with Asthma.

PURPOSE: To evaluate the effects of air purifiers on the concentrations of indoor air pollutants and on asthma control in children. MATERIALS AND METHODS: In this randomized crossover trial, daily use of an air purifier filter was compared with a matched placebo with the filter off. Thirty elementary school students who had asthma were enrolled and randomly allocated to one of two groups. The primary endpoints were changes in indoor air quality, asthma severity, lung function, airway inflammatory, urine microbiome, and phthalate after the installation of air purifiers. PM2.5 and CO2 were measured as indoor air pollutants. Asthma severity was assessed in terms of both symptom and medication scores acquired using a daily questionnaire. The higher the score, the better the symptom or the less frequent the use of medication. Peak expiratory flow rate and fractional exhaled nitric oxide were also measured. RESULTS: The mean age of the enrolled patients was 9.2±1.98 years. The mean concentration of PM2.5 was 17.0 µg/m³ in the filter-off condition, but significantly lower at 9.26 µg/m³ in the filter-on condition. Medication scores were 6.9 for the filter-off and 7.12 for the filter-on conditions, reflecting a statistically significant decrease in the frequency of medications used during air purifier operation. Bacterial richness, as determined using the Chao 1 index, was markedly lower in the filter-on than the filter-off condition. CONCLUSION: This study suggests that air purifiers benefit medication burden in children with asthma by reducing PM2.5 levels.

Association between Peak Expiratory Flow Rate and Exposure Level to Indoor PM2.5 in Asthmatic Children, Using Data from the Escort Intervention Study.

Various studies have indicated that particulate matter <2.5 µm (PM2.5) could cause adverse health effects on pulmonary functions in susceptible groups, especially asthmatic children. Although the impact of ambient PM2.5 on children's lower respiratory health has been well-established, information regarding the associations between indoor PM2.5 levels and respiratory symptoms in asthmatic children is relatively limited. This randomized, crossover intervention study was conducted among 26 asthmatic children's homes located in Incheon metropolitan city, Korea. We aimed to evaluate the effects of indoor PM2.5 on children's peak expiratory flow rate (PEFR), with a daily intervention of air purifiers with filter on, compared with those groups with filter off. Children aged between 6-12 years diagnosed with asthma were enrolled and randomly allocated into two groups. During a crossover intervention period of seven weeks, we observed that, in the filter-on group, indoor PM2.5 levels significantly decreased by up to 43%. (p < 0.001). We also found that the daily or weekly unit (1 µg/m3) increase in indoor PM2.5 levels could significantly decrease PEFR by 0.2% (95% confidence interval (CI) = 0.1 to 0.5) or PEFR by 1.2% (95% CI = 0.1 to 2.7) in asthmatic children, respectively. The use of in-home air filtration could be considered as an intervention strategy for indoor air quality control in asthmatic children's homes.