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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Impact of Grilling Meat or Fish at Home on Peak Expiratory Flow Rate in Adults With Asthma.

Grilling, a common cooking method worldwide, can produce more toxic gases than other cooking methods. However, the impact of frequently grilling meat or fish at home on airflow limitation in adult asthma has not been well elucidated. We performed a prospective cohort study of 91 adult patients with asthma enrolled from 2 university hospitals. Of the patients, 39 (42.9%) grilled meat or fish at least once a week and 52 (57.1%) less than once a week. Patients who grilled at least once a week tended to have lower peak expiratory flow rate (PEFR) than those who grilled less than once a week (median, 345.5 L/min; 95% confidence interval [CI], 291.8-423.2 L/min vs. median, 375.1 L/min; 95% CI, 319.7-485.7 L/min; P = 0.059). Among patients with severe asthma who received step 4-5 treatment, PEFR was significantly lower in patients who grilled at least once a week compared with those who grilled less than once a week (median, 297.8 L/min; 95% CI, 211.3-357.7 L/min vs. median, 396.1 L/min; 95% CI, 355.0-489.6 L/min; P < 0.001). Our results suggest that the frequency of grilling meat or fish at home may affect PEFR in asthmatic patients, especially those with severe asthma who needed a high level of asthma treatment.

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.

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.

Association between the Ratio of FEV1 to FVC and the Exposure Level to Air Pollution in Neversmoking Adult Refractory Asthmatics Using Data Clustered by Patient in the Soonchunhyang Asthma Cohort Database.

Using real-world cases, asthma-related clinical data were clustered by patient; 5% of all asthmatics were found to have refractory asthma (RA) with a relatively low lung function (forced expiratory volume in 1 s/forced vital capacity (FEV1/FVC) less than 80%). Using a multilevel study design for clustered spirometry data observed between 2005 and 2014, we evaluated the association between changes in the ratio of FEV1 to FVC and variations in acute exposure to air pollution. We analyzed 2310 episodes of RA from 214 neversmoking patients. In spring, a 1 µg/m³ increase in concentration of particles ≤10 µm (PM10) on Lag 1 significantly reduced the ratio by 0.4% (95% confidence interval (CI): 0.1⁻0.7%) after adjusting for sex, age, body mass index (BMI), and total Immunoglobulin E (IgE) level. Unit (ppb) increase in SO2 concentration on Lag 3 and 4 in fall and on Lag 6 in winter significantly reduced the ratio by 2 to 3% (p < 0.05). We found that acute exposure to PM10 in spring or SO2 in fall or winter were positively associated with lung function drop indicating necessity of control strategies of target air pollutant source by season to protect susceptible population.

Smoking Topography among Korean Smokers: Intensive Smoking Behavior with Larger Puff Volume and Shorter Interpuff Interval.

The difference of smoker's topography has been found to be a function many factors, including sex, personality, nicotine yield, cigarette type (i.e., flavored versus non-flavored) and ethnicity. We evaluated the puffing behaviors of Korean smokers and its association with smoking-related biomarker levels. A sample of 300 participants was randomly recruited from metropolitan areas in South Korea. Topography measures during a 24-hour period were obtained using a CReSS pocket device. Korean male smokers smoked two puffs less per cigarette compared to female smokers (15.0 (13.0⁻19.0) vs. 17.5 (15.0⁻21.0) as the median (Interquartile range)), but had a significantly larger puff volume (62.7 (52.7⁻75.5) mL vs. 53.5 (42.0⁻64.2) mL); p = 0.012). The interpuff interval was similar between men and women (8.9 (6.5⁻11.2) s vs. 8.3 (6.2⁻11.0) s; p = 0.122) but much shorter than other study results. A dose-response association (p = 0.0011) was observed between daily total puff volumes and urinary cotinine concentrations, after controlling for sex, age, household income level and nicotine addiction level. An understanding of the difference of topography measures, particularly the larger puff volume and shorter interpuff interval of Korean smokers, may help to overcome a potential underestimation of internal doses of hazardous byproducts of smoking.

Spatiotemporal Association of Real-Time Concentrations of Black Carbon (BC) with Fine Particulate Matters (PM2.5) in Urban Hotspots of South Korea.

We evaluated the spatiotemporal distributions of black carbon (BC) and particulate matters with aerodynamic diameters of less than 2.5 m (PM2.5) concentrations at urban diesel engine emission (DEE) hotspots of South Korea. Concentrations of BC and PM2.5 were measured at the entrance gate of two diesel bus terminals and a train station, in 2014. Measurements were conducted simultaneously at the hotspot (Site 1) and at its adjacent, randomly selected, residential areas, apartment complex near major roadways, located with the same direction of 300 m (Site 2) and 500 m (Site 3) away from Site 1 on 4 different days over the season, thrice per day; morning (n = 120 measurements for each day and site), evening (n = 120), and noon (n = 120). The median (interquartile range) PM2.5 ranged from 12.6 (11.3-14.3) to 60.1 (47.0-76.0) µg/m³ while those of BC concentrations ranged from 2.6 (1.9-3.7) to 6.3 (4.2-10.3) µg/m³. We observed a strong relationship of PM2.5 concentrations between sites (slopes 0.89-0.9, the coefficient of determination 0.89-0.96) while the relationship for BC concentrations between sites was relatively weak (slopes 0.76-0.85, the coefficient of determination 0.54-0.72). PM2.5 concentrations were changed from 4% to 140% by unit increase of BC concentration, depending on site and time while likely supporting the necessity of monitoring of BC as well as PM2.5, especially at urban DEE related hotspot areas.

Evaluation of Potential Average Daily Doses (ADDs) of PM2.5 for Homemakers Conducting Pan-Frying Inside Ordinary Homes under Four Ventilation Conditions.

Several studies reported that commercial barbecue restaurants likely contribute to the indoor emission of particulate matters with a diameter of 2.5 micrometers or less (PM2.5) while pan-frying meat. However, there is inadequate knowledge of exposure level to indoor PM2.5 in homes and the contribution of a typical indoor pan-frying event. We measured the indoor PM2.5 concentration and, using Monte-Carlo simulation, estimated potential average daily dose (ADD) of PM2.5 for homemakers pan-frying a piece of pork inside ordinary homes. Convenience-based sampling at 13 homes was conducted over four consecutive days in June 2013 (n = 52). Although we pan-fried 100 g pork for only 9 min, the median (interquartile range, IQR) value was 4.5 (2.2-5.6) mg/m³ for no ventilation and 0.5 (0.1-1.3) mg/m³ with an active stove hood ventilation system over a 2 h sampling interval. The probabilities that the ADDs from inhalation of indoor PM2.5 would be higher than the ADD from inhalation of PM2.5 on an outdoor roadside (4.6 µg/kg·day) were 99.44%, 97.51%, 93.64%, and 67.23%, depending on the ventilation conditions: (1) no window open; (2) one window open in the kitchen; (3) two windows open, one each in the kitchen and living room; and (4) operating a forced-air stove hood, respectively.

Overview of Cotinine Cutoff Values for Smoking Status Classification.

While cotinine is commonly used as a biomarker to validate self-reported smoking status, the selection of an optimal cotinine cutoff value for distinguishing true smokers from true nonsmokers shows a lack of standardization among studies. This review describes how the cutoff values have been derived, and explains the issues involved in the generalization of a cutoff value. In this study, we conducted an English-language literature search in PubMed using the keywords "cotinine" and "cutoff" or "self-reported" and "smoking status" and "validation" for the years 1985-2014. We obtained 104 articles, 32 of which provided (1) sensitivity and specificity of a cutoff value and (2) determination methods for the given cutoff value. We found that the saliva cotinine cutoff value range of 10-25 ng/mL, serum and urine cotinine cutoff of 10-20 ng/mL and 50-200 ng/mL, respectively, have been commonly used to validate self-reported smoking status using a 2 × 2 table or a receiver operating characteristics (ROC) curve. We also found that recent large population-based studies in the U.S. and UK reported lower cutoff values for cotinine in serum (3 ng/mL) and saliva (12 ng/mL), compared to the traditionally accepted ones (15 and 14 ng/mg, respectively).