Effect of polycyclic aromatic hydrocarbon exposure on amnestic mild cognitive impairment and Alzheimer's disease: A matched case-control study.

There is an emerging body of evidence concerning the neurological effect of air pollutants on cognitive function and increased risk of neurodegeneration. Although previous studies have suggested that polycyclic aromatic hydrocarbons (PAHs) are neurotoxic, the effect of PAHs exposure on neurodegeneration remains unclear. This study aimed to investigate the association between PAH exposure and the risk of developing amnestic mild cognitive impairment (aMCI) and Alzheimer's disease (AD). For this matched case-control cross-sectional study, we recruited patients aged ≥50 years diagnosed with aMCI and AD from the Samsung Medical Center, Seoul, Korea, between 2014 and 2019. For each patient, we randomly selected four cognitively healthy controls through frequency matching based on sex, age group, and education level. Urinary levels of four PAH metabolites, 1-hydroxypyrene (1-OHP), 1-hydroxyphenanthrene (1-OHPhe), 2-hydroxyfluorene (2-OHFlu), and 2-naphthol (2-NAP), were measured. A conditional logistic regression model was used to evaluate the association, adjusting for potential confounders. A total of 212 patients with aMCI with 848 matched controls, and 267 patients with AD with 1068 matched controls were included in the analyses to estimate the risk of PAH exposure. We found that elevated urinary levels of PAH metabolites (specifically, 1-OHP and 2-NAP) were significantly associated with an increased risk of aMCI and AD. An increase of one unit in log-transformed level of urinary 1-OHP was associated with a 1.15- and 1.16-times higher risk of aMCI and AD, respectively. An increase of one unit in log-transformed level of urinary 2-NAP was associated with a 1.11- and 1.13-times higher risk of aMCI and AD, respectively. These findings indicate that PAH exposure may increase the risk of aMCI and AD, especially for the elderly population. Considering the widespread distribution of PAHs in the environment, reducing PAH exposure may be an effective strategy for the prevention of neurodegenerative diseases.

Effects of Ambient Air Pollution on Brain Cortical Thickness and Subcortical Volume: A Longitudinal Neuroimaging Study.

INTRODUCTION: Several cross-sectional studies have shown that long-term exposures to air pollutants are associated with smaller brain cortical volume or thickness. Here, we investigated longitudinal associations of long-term air pollution exposures with cortical thickness and subcortical volume. METHODS: In this longitudinal study, we included a prospective cohort of 361 adults residing in four cities in the Republic of Korea. Long-term concentrations of particulate matter with aerodynamic diameters of ≤10 µm (PM10) and ≤2.5 µm (PM2.5) and nitrogen dioxide (NO2) at residential addresses were estimated. Neuroimaging markers (cortical thickness and subcortical volume) were obtained from brain magnetic resonance images at baseline (August 2014 to March 2017) and at the 3-year follow-up (until September 2020). Linear mixed-effects models were used, adjusting for covariates. RESULTS: A 10-µg/m3 increase in PM10 was associated with reduced whole-brain mean (ß = -0.45, standard error [SE] = 0.10; p < 0.001), frontal (ß = -0.53, SE = 0.11; p < 0.001) and temporal thicknesses (ß = -0.37, SE = 0.12; p = 0.002). A 10-ppb increase in NO2 was associated with a decline in the whole-brain mean cortical thickness (ß = -0.23, SE = 0.05; p < 0.001), frontal (ß = -0.25, SE = 0.05; p < 0.001), parietal (ß = -0.12, SE = 0.05; p = 0.025), and temporal thicknesses (ß = -0.19, SE = 0.06; p = 0.001). Subcortical structures associated with air pollutants included the thalamus. CONCLUSIONS: Long-term exposures to PM10 and NO2 may lead to cortical thinning in adults.

Physical Activity-Induced Modification of the Association of Long-Term Air Pollution Exposure with the Risk of Depression in Older Adults.

PURPOSE: Evidence suggests that long-term air pollution exposures may induce depression; however, the influence of physical activity on this effect is unclear. We investigated modification of the associations between air pollution exposures and depression by the intensity of physical activity. MATERIALS AND METHODS: This cross-sectional study included 1454 Korean adults. Depression was defined as a Geriatric Depression Scale score ≥8. Concentrations of particulate matter (PM10 and PM2.5: diameter ≤10 µm and ≤2.5 µm, respectively) and nitrogen dioxide (NO2) level at each participant's residential address were estimated. Based on metabolic equivalents, physical activity intensity was categorized as inactive, minimally active, or health-enhancing physical activity (HEPA). RESULTS: Each 1-part per billion (ppb) NO2 concentration increase was significantly associated with a 6% [95% confidence interval (CI), 4%-8%] increase in depression risk. In older adults (≥65 years), a 1-ppb NO2 increase was associated (95% CI) with a 4% (1%-7%), 9% (5%-13%), and 21% (9%-33%) increase in depression risk in the inactive, minimally active, and HEPA groups, respectively. Compared with the inactive group, the minimally active (p=0.039) and HEPA groups (p=0.004) had higher NO2 exposure-associated depression risk. Associations of PM10 and PM2.5 with depression did not significantly differ by the intensity of physical activity. CONCLUSION: We suggest that older adults who vigorously exercise outdoors may be susceptible to air pollution-related depression.

Polycyclic aromatic hydrocarbons and changes in brain cortical thickness and an Alzheimer's disease-specific marker for cortical atrophy in adults: A longitudinal neuroimaging study of the EPINEF cohort.

Although several epidemiological studies have suggested that exposure to polycyclic aromatic hydrocarbons (PAHs) may induce brain atrophy, no longitudinal study has investigated the effect of PAH exposure on brain structural changes. This study examined the longitudinal associations between urinary PAH metabolites and brain cortical thickness. We obtained urinary concentrations of PAH metabolites and brain magnetic resonance images from 327 adults (≥50 years of age) without dementia at baseline and 3-year follow-up. We obtained whole-brain and regional cortical thicknesses, as well as an Alzheimer's disease (AD)-specific marker for cortical atrophy (a higher score indicated a greater similarity to patients with AD) at baseline and follow-up. We built a linear mixed-effect model including each of urinary PAH metabolites as the time-varying exposure variable of interest. We found that increases in urinary concentrations of 1-hydroxypyrene (ß = -0.004; 95% CI, -0.008 to -0.001) and 2-hydroxyfluorene (ß = -0.011; 95% CI, -0.015 to -0.006) were significantly associated with a reduced whole-brain cortical thickness. A urinary concentration of 2-hydroxyfluorene was significantly associated with an increased AD-specific cortical atrophy score (ß = 2.031; 95% CI, 0.512 to 3.550). The specific brain regions showing the association of urinary concentrations of 1-hydroxypyrene, 2-naphthol, 1-hydroxyphenanthrene, or 2-hydroxyfluorene with cortical thinning were the frontal, parietal, temporal, and cingulate lobes. These findings suggested that exposure to PAHs may reduce brain cortical thickness and increase the similarity to AD-specific cortical atrophy patterns in adults.

Health Effects of Microplastic Exposures: Current Issues and Perspectives in South Korea.

Microplastics are environmental pollutants that prevail in the oceans, remote islands, and polar regions. Exposure to microplastics presents a major emerging threat to the ecosystems due to their potential adverse effects. Herein, we reviewed the literature to provide an up-to-date synopsis of the current understanding of the sources, compositions, and adverse effects of microplastics in humans and the environment. Most studies on microplastics have focused on developing standardized methods for monitoring the occurrence, distribution, and movement of microplastics in the environment, as well as developing microplastic substitutes; however, although humans are exposed to microplastics via various routes, research on the adverse effects of microplastics in humans remains limited. Little is known about the impact of microplastics on human health and the toxic effects that may vary depending on the type, size, shape, and concentration of microplastics. Therefore, more research is needed to understand the cellular and molecular mechanisms of microplastic toxicity and related pathologies.

Changes in Expenditures of the National Health Insurance of Korea during the COVID-19 Pandemic and the Financial Implications Thereof.

As the number of coronavirus disease 2019 (COVID-19) patients increased rapidly, the Korean government decided to pay most of the related medical expenses with finances from the National Health Insurance (NHI). We aimed to document changes in NHI medical expenses during the COVID-19 pandemic period. We also sought to compare how Japan and Taiwan, neighboring countries with NHI systems, responded to COVID-19 and to discuss policy implications.

Alzheimer's disease-like cortical atrophy mediates the effect of air pollution on global cognitive function.

Little is known about the effect of air pollution on Alzheimer's disease (AD)-specific brain structural pathologies. There is also a lack of evidence on whether this effect leads to poorer cognitive function. We investigated whether, and the extent to which, AD-like cortical atrophy mediated the association between air pollution exposures and cognitive function in dementia-free adults. We used cross-sectional data from 640 participants who underwent brain magnetic resonance imaging and the Montreal Cognitive Assessment (MoCA). Mean cortical thickness (as the measure of global cortical atrophy) and machine learning-based AD-like cortical atrophy score were estimated from brain images. Concentrations of particulate matter with diameters ≤ 10 µm (PM10) and ≤ 2.5 µm (PM2.5) and nitrogen dioxide (NO2) were estimated based on each participant's residential address. Following the product method, a mediation effect was tested by conducting a series of three regression analyses (exposure to outcome; exposure to mediator; and exposure and mediator to outcome). A 10 µg/m3 increase in PM10 (ß = -1.13; 95 % CI, -1.73 to -0.53) and a 10 ppb increase in NO2 (ß = -1.09; 95 % CI, -1.40 to -0.78) were significantly associated with a lower MoCA score. PM10 (ß = 0.27; 95 % CI, 0.06 to 0.48) and NO2 (ß = 0.35; 95 % CI, 0.25 to 0.45) were significantly associated with an increased AD-like cortical atrophy score. Effects of PM10 and NO2 on MoCA scores were significantly mediated by mean cortical thickness (proportions mediated: 25 %-28 %) and AD-like cortical atrophy scores (13 %-16 %). The findings suggest that air pollution exposures may induce AD-like cortical atrophy, and that this effect may lead to poorer cognitive function in dementia-free adults.

Control Aspects of Shape Memory Alloys in Robotics Applications: A Review over the Last Decade.

This paper mainly focuses on various types of robots driven or actuated by shape memory alloy (SMA) element in the last decade which has created the potential functionality of SMA in robotics technology, that is classified and discussed. The wide spectrum of increasing use of SMA in the development of robotic systems is due to the increase in the knowledge of handling its functional characteristics such as large actuating force, shape memory effect, and super-elasticity features. These inherent characteristics of SMA can make robotic systems small, flexible, and soft with multi-functions to exhibit different types of moving mechanisms. This article comprehensively investigates three subsections on soft and flexible robots, driving or activating mechanisms, and artificial muscles. Each section provides an insight into literature arranged in chronological order and each piece of literature will be presented with details on its configuration, control, and application.

Cohort profile: the Environmental-Pollution-Induced Neurological EFfects (EPINEF) study: a multicenter cohort study of Korean adults.

The general population is exposed to numerous environmental pollutants, and it remains unclear which pollutants affect the brain, accelerating brain aging and increasing the risk of dementia. The Environmental-Pollution-Induced Neurological Effects study is a multi-city prospective cohort study aiming to comprehensively investigate the effect of different environmental pollutants on brain structures, neuropsychological function, and the development of dementia in adults. The baseline data of 3,775 healthy elderly people were collected from August 2014 to March 2018. The eligibility criteria were age ≥50 years and no self-reported history of dementia, movement disorders, or stroke. The assessment included demographics and anthropometrics, laboratory test results, and individual levels of exposure to air pollution. A neuroimaging sub-cohort was also recruited with 1,022 participants during the same period, and brain magnetic resonance imaging and neuropsychological tests were conducted. The first follow-up environmental pollutant measurements will start in 2022 and the follow-up for the sub-cohort will be conducted every 3-4 years. We have found that subtle structural changes in the brain may be induced by exposure to airborne pollutants such as particulate matter 10 µm or less in diameter (PM10), particulate matter 2.5 µm or less in diameter (PM2.5) and Mn10, manganese in PM10; Mn2.5, manganese in PM2.5. PM10, PM2.5, and nitrogen dioxide in healthy adults. This study provides a basis for research involving large-scale, long-term neuroimaging assessments in community-based populations.

Autonomous Assessment of Delamination Using Scarce Raw Structural Vibration and Transfer Learning.

Deep learning has helped achieve breakthroughs in a variety of applications; however, the lack of data from faulty states hinders the development of effective and robust diagnostic strategies using deep learning models. This work introduces a transfer learning framework for the autonomous detection, isolation, and quantification of delamination in laminated composites based on scarce low-frequency structural vibration data. Limited response data from an electromechanically coupled simulation model and from experimental testing of laminated composite coupons were encoded into high-resolution time-frequency images using SynchroExtracting Transforms (SETs). The simulated and experimental data were processed through different layers of pretrained deep learning models based on AlexNet, GoogleNet, SqueezeNet, ResNet-18, and VGG-16 to extract low- and high-level autonomous features. The support vector machine (SVM) machine learning algorithm was employed to assess how the identified autonomous features were able to assist in the detection, isolation, and quantification of delamination in laminated composites. The results obtained using these autonomous features were also compared with those obtained using handcrafted statistical features. The obtained results are encouraging and provide a new direction that will allow us to progress in the autonomous damage assessment of laminated composites despite being limited to using raw scarce structural vibration data.

The effect of body fatness on regional brain imaging markers and cognitive function in healthy elderly mediated by impaired glucose metabolism.

Brain atrophy is related to vascular risk factors and can increase cognitive dysfunction risk. This community-based, cross-sectional study investigated whether glucose metabolic disorders due to body fatness are linked to regional changes in brain structure and a decline in neuropsychological function in cognitively healthy older adults. From 2016 to 2019, 429 participants underwent measurements for cortical thickness and subcortical volume using 3 T magnetic resonance imaging and for cognitive function using the neuropsychological screening battery. The effects of body fatness mediated by impaired glucose metabolism on neuroimaging markers and cognitive function was investigated using partial least square structural equation modeling. Total grey matter volume (ß = -0.020; bias-corrected (BC) 95% confidence interval (CI) = -0.047 to -0.006), frontal (ß = -0.029; BC 95% CI = -0.063 to -0.005) and temporal (ß = -0.022; BC 95% CI = -0.051 to -0.004) lobe cortical thickness, and hippocampal volume (ß = -0.029; BC 95% CI = -0.058 to -0.008) were indirectly related to body fatness. Further, frontal/temporal lobe thinning was associated with recognition memory (ß = -0.005; BC 95% CI = -0.012 to -0.001/ß = -0.005; BC 95% CI = -0.013 to -0.001) and delayed recall for visual information (ß = -0.005; BC 95% CI = -0.013 to -0.001/ß = -0.005; BC 95% CI = -0.013 to -0.001). Additionally, the smaller the hippocampal volume, the lower the score in recognition memory (ß = -0.005; BC 95% CI = -0.012 to -0.001), delayed recall for visual information (ß = -0.005; BC 95% CI = -0.012 to -0.001), and verbal learning (ß = -0.008; BC 95% CI = -0.017 to -0.002). Our findings indicate that impaired glucose metabolism caused by excess body fatness affects memory decline as well as regional grey matter atrophy in elderly individuals with no neurological disease.

Long-Term Ambient Air Pollution Exposures and Brain Imaging Markers in Korean Adults: The Environmental Pollution-Induced Neurological EFfects (EPINEF) Study.

BACKGROUND: Only a limited number of neuroimaging studies have explored the effects of ambient air pollution in adults. The prior studies have investigated only cortical volume, and they have reported mixed findings, particularly for gray matter. Furthermore, the association between nitrogen dioxide (NO2) and neuroimaging markers has been little studied in adults. OBJECTIVES: We investigated the association between long-term exposure to air pollutants (NO2, particulate matter (PM) with aerodynamic diameters of ≤10µm (PM10) and ≤2.5µm (PM2.5), and neuroimaging markers. METHODS: The study included 427 men and 530 women dwelling in four cities in the Republic of Korea. Long-term concentrations of PM10, NO2, and PM2.5 at residential addresses were estimated. Neuroimaging markers (cortical thickness and subcortical volume) were obtained from brain magnetic resonance images. A generalized linear model was used, adjusting for potential confounders. RESULTS: A 10-µg/m3 increase in PM10 was associated with reduced thicknesses in the frontal [-0.02mm (95% CI: -0.03, -0.01)] and temporal lobes [-0.06mm (95% CI: -0.07, -0.04)]. A 10-µg/m3 increase in PM2.5 was associated with a thinner temporal cortex [-0.18mm (95% CI: -0.27, -0.08)]. A 10-ppb increase in NO2 was associated with reduced thicknesses in the global [-0.01mm (95% CI: -0.01, 0.00)], frontal [-0.02mm (95% CI: -0.03, -0.01)], parietal [-0.02mm (95% CI: -0.03, -0.01)], temporal [-0.04mm (95% CI: -0.05, -0.03)], and insular lobes [-0.01mm (95% CI: -0.02, 0.00)]. The air pollutants were also associated with increased thicknesses in the occipital and cingulate lobes. Subcortical structures associated with the air pollutants included the thalamus, caudate, pallidum, hippocampus, amygdala, and nucleus accumbens. DISCUSSION: The findings suggest that long-term exposure to high ambient air pollution may lead to cortical thinning and reduced subcortical volume in adults. https://doi.org/10.1289/EHP7133.

Association between exposure to polycyclic aromatic hydrocarbons and brain cortical thinning: The Environmental Pollution-Induced Neurological EFfects (EPINEF) study.

BACKGROUND: Although some studies have suggested that exposure to polycyclic aromatic hydrocarbons (PAHs) induces neurodevelopmental disturbances in children and neurodegeneration in animals, the neurotoxic effect of PAH exposure is unclear in adults. The aim was to examine the associations of PAH exposure with brain structure and neuropsychological function in adults without known neurological diseases. METHODS: This study included 421 men and 528 women dwelling in four cities in the Republic of Korea. Urinary concentrations of four PAH metabolites (1-hydroxypyrene, 2-naphthol, 1-hydroxyphenanthrene, and 2-hydroxyfluorene) were obtained. Participants underwent brain 3 T magnetic resonance imaging and neuropsychological tests. Cortical thickness and volume were estimated using the region-of-interest method. Separate generalized linear models were constructed for each sex, adjusting for age, years of education, cohabitation status, income, tobacco use, alcohol consumption, and vascular risk factors. RESULTS: The mean (standard deviation) age was 68.3 (6.6) years in men and 66.4 (6.1) years in women. In men, those in quartile 4 (versus quartile 1, the lowest) of urinary 2-naphthol concentration had cortical thinning in the global (ß = -0.03, P = .02), parietal (ß = -0.04, P = .01), temporal (ß = -0.06, P < .001), and insular lobes (ß = -0.05, P = .02). Higher quartiles of urinary 2-naphthol concentration were associated with cortical thinning in the global (P = .01), parietal (P = .004), temporal (P < .001), and insular lobes (P = .01). In women, those in quartile 4 (versus quartile 1) of urinary 1-hydroxypyrene concentration had cortical thinning in the frontal (ß = -0.03, P = .006) and parietal lobes (ß = -0.03, P = .003). Higher quartiles of urinary 1-hydroxypyrene concentration were associated with cortical thinning in the frontal (P = .006) and parietal lobes (P = .001). In both sexes, verbal learning and memory scores significantly declined with an increase in quartile of urinary 1-hydroxypyrene concentration. CONCLUSIONS: PAH exposure was associated with cortical thinning and decline in verbal learning and memory function in cognitively healthy adults. This suggests PAHs as an environmental risk factor for neurodegeneration.

Long-term Effects of Cumulative Average PM2.5 Exposure on the Risk of Hemorrhagic Stroke.

BACKGROUND: Epidemiological studies have revealed associations between the fine particle (PM2.5; aerodynamic diameter <2.5 µm) exposure and cardiovascular disease. Researchers have also recently begun investigating the association between PM2.5 exposure and hemorrhagic stroke (HS) and identifying subpopulations vulnerable to PM2.5 exposure. Long-term cumulative average PM2.5 exposure may affect the risk of HS, and these effects may be modified by risk factors. METHODS: This retrospective study evaluated the effects of PM2.5 on the time-to-first-diagnosis of HS among 62,676 Seoul metropolitan city residents with 670,431 total person-years of follow-up; this cohort is a subset from a nationally representative cohort of 1,025,340 individuals from the Korean National Health Insurance Service database (2002-2013). A time-dependent Cox proportional hazards model was used to adjust for age, sex, household income, insurance type, body mass index, smoking status, medical history, and family history. The annual mean PM2.5 concentrations for 25 districts were used as the time-dependent variable. Subgroup analyses of the traditional risk factors of HS were performed to evaluate potential effect modifications. RESULTS: Each 10-µg/m increment in cumulative average PM2.5 exposure was noticeably associated with HS (hazard ratio [HR] = 1.43; 95% confidence interval [CI]: 1.09-1.88). The adverse effects of PM2.5 exposure were modified by ≥65 years of age (HR = 2.00; 95% CI = 1.32, 3.02) and obesity (body mass index ≥25 kg/m; HR = 1.91; 95% CI = 1.28, 2.84). CONCLUSIONS: Cumulative average PM2.5 exposure might increase the risk of HS. Elderly (≥65 years) and obese individuals may be more vulnerable to the effects of PM2.5 exposure.

Short-term Effect of Ambient Air Pollution on Emergency Department Visits for Diabetic Coma in Seoul, Korea.

OBJECTIVES: A positive association between air pollution and both the incidence and prevalence of diabetes mellitus (DM) has been reported in some epidemiologic and animal studies, but little research has evaluated the relationship between air pollution and diabetic coma. Diabetic coma is an acute complication of DM caused by diabetic ketoacidosis or hyperosmolar hyperglycemic state, which is characterized by extreme hyperglycemia accompanied by coma. We conducted a time-series study with a generalized additive model using a distributed-lag non-linear model to assess the association between ambient air pollution (particulate matter less than 10 µm in aerodynamic diameter, nitrogen dioxide [NO2], sulfur dioxide, carbon monoxide, and ozone) and emergency department (ED) visits for DM with coma in Seoul, Korea from 2005 to 2009. METHODS: The ED data and medical records from the 3 years previous to each diabetic coma event were obtained from the Health Insurance Review and Assessment Service to examine the relationship with air pollutants. RESULTS: Overall, the adjusted relative risks (RRs) for an interquartile range (IQR) increment of NO2 was statistically significant at lag 1 (RR, 1.125; 95% confidence interval [CI], 1.039 to 1.219) in a single-lag model and both lag 0-1 (RR, 1.120; 95% CI, 1.028 to 1.219) and lag 0-3 (RR, 1.092; 95% CI, 1.005 to 1.186) in a cumulative-lag model. In a subgroup analysis, significant positive RRs were found for females for per-IQR increments of NO2 at cumulative lag 0-3 (RR, 1.149; 95% CI, 1.022 to 1.291). CONCLUSIONS: The results of our study suggest that ambient air pollution, specifically NO2, is associated with ED visits for diabetic coma.

Geographical variations and influential factors in prevalence of cardiometabolic diseases in South Korea.

Geographical variations and influential factors of disease prevalence are crucial information enabling optimal allocation of limited medical resources and prioritization of appropriate treatments for each regional unit. The purpose of this study was to explore the geographical variations and influential factors of cardiometabolic disease prevalence with respect to 230 administrative districts in South Korea. Global Moran's I was calculated to determine whether the standardized prevalences of cardiometabolic diseases (hypertension, stroke, and diabetes mellitus) were spatially clustered. The CART algorithm was then applied to generate decision tree models that could extract the diseases' regional influential factors from among 101 demographic, economic, and public health data variables. Finally, the accuracies of the resulting model-hypertension (67.4%), stroke (62.2%), and diabetes mellitus (56.5%)-were assessed by ten-fold cross-validation. Marriage rate was the main determinant of geographic variation in hypertension and stroke prevalence, which has the possibility that married life could have positive effects in lowering disease risks. Additionally, stress-related variables were extracted as factors positively associated with hypertension and stroke. In the opposite way, the wealth status of a region was found to have an influence on the prevalences of stroke and diabetes mellitus. This study suggested a framework for provision of novel insights into the regional characteristics of diseases and the corresponding influential factors. The results of the study are anticipated to provide valuable information for public health practitioners' cost-effective disease management and to facilitate primary intervention and mitigation efforts in response to regional disease outbreaks.

Effect of Socioeconomic Status and Underlying Disease on the Association between Ambient Temperature and Ischemic Stroke.

PURPOSE: Inconsistent findings have been reported regarding the effect of ambient temperature on ischemic stroke. Furthermore, little is known about how underlying disease and low socioeconomic status influence the association. We, therefore, investigated the relationship between ambient temperature and emergency department (ED) visits for ischemic stroke, and aimed to identify susceptible populations. MATERIALS AND METHODS: Using medical claims data, we identified ED visits for ischemic stroke during 2005-2009 in Seoul, Korea. We conducted piecewise linear regression analyses to find optimum ambient temperature thresholds in summer and winter, and estimated the relative risks (RR) and 95% confidence intervals (CI) per a 1°C increase in temperature above/below the thresholds, adjusting for relative humidity, holidays, day of the week, and air pollutant levels. RESULTS: There were 63564 ED visits for ischemic stroke. In summer, the risk of ED visits for ischemic stroke was not significant, with the threshold at 26.8°C. However, the RRs were 1.055 (95% CI, 1.006-1.106) above 25.0°C in medical aid beneficiaries and 1.044 (1.007-1.082) above 25.8°C in patients with diabetes. In winter, the risk of ED visits for ischemic stroke significantly increased as the temperature decreased above the threshold at 7.2°C. This inverse association was significant also in patients with hypertension and diabetes mellitus above threshold temperatures. CONCLUSION: Ambient temperature increases above a threshold were positively associated with ED visits for ischemic stroke in patients with diabetes and medical aid beneficiaries in summer. In winter, temperature, to a point, and ischemic stroke visits were inversely associated.

Association of air pollution with increased incidence of ventricular tachyarrhythmias recorded by implantable cardioverter defibrillators: Vulnerable patients to air pollution.

BACKGROUND: This study investigated the acute effects of exposure to air pollution on ventricular tachyarrhythmias (VTAs) in an East Asian population. The association between air pollution and VTA has not yet been studied in an East Asian country affected by the Asian dust phenomenon, which worsens air quality. METHODS: The study cohort consisted of 160patients with implantable cardioverter defibrillator (ICD) devices in the Seoul metropolitan area who were followed for 5.5±3.8years. We used ICD records of VTAs and matched these with hourly measurements of air pollutant concentrations and meteorological data. Fine particle mass and gaseous air pollution plus temperature and relative humidity were measured hourly during the study period. RESULTS: During the study period, 1064 VTA events including 204 instances of ventricular fibrillation (VF) were observed. We found a statistically significant association between overall VTA events and SO2 (lag 24h; OR 1.49, 95%CI 1.16-1.92, p=0.002), PM10 (lag 2h; OR 2.56, 95%CI 2.03-3.23, p<0.001), NO2 (lag 24h; OR 1.25, 95%CI 1.19-1.31, p<0.001) and CO (lag 24h; OR 1.05, 95%CI 1.02-1.08, p=0.003). Sustained ventricular tachycardia or VF was also independently associated with SO2, PM10, NO2 and CO (all p<0.01). Exposures to SO2, PM10, NO2, and CO (all p<0.01) were significantly related to overall VTAs, especially in patients with structural heart disease (SHD). CONCLUSIONS: Associations between air pollution and VTA were observed in a metropolitan area of an East Asian country. Exposures to SO2, PM10, NO2, and CO were significantly associated with VTAs in ICD patients with SHD.

Short-term Effects of Ambient Air Pollution on Emergency Department Visits for Asthma: An Assessment of Effect Modification by Prior Allergic Disease History.

OBJECTIVES: The goal of this study was to investigate the short-term effect of ambient air pollution on emergency department (ED) visits in Seoul for asthma according to patients' prior history of allergic diseases. METHODS: Data on ED visits from 2005 to 2009 were obtained from the Health Insurance Review and Assessment Service. To evaluate the risk of ED visits for asthma related to ambient air pollutants (carbon monoxide [CO], nitrogen dioxide [NO2], ozone [O3], sulfur dioxide [SO2], and particulate matter with an aerodynamic diameter <10 µm [PM10]), a generalized additive model with a Poisson distribution was used; a single-lag model and a cumulative-effect model (average concentration over the previous 1-7 days) were also explored. The percent increase and 95% confidence interval (CI) were calculated for each interquartile range (IQR) increment in the concentration of each air pollutant. Subgroup analyses were done by age, gender, the presence of allergic disease, and season. RESULTS: A total of 33 751 asthma attack cases were observed during the study period. The strongest association was a 9.6% increase (95% CI, 6.9% to 12.3%) in the risk of ED visits for asthma per IQR increase in O3 concentration. IQR changes in NO2 and PM10 concentrations were also significantly associated with ED visits in the cumulative lag 7 model. Among patients with a prior history of allergic rhinitis or atopic dermatitis, the risk of ED visits for asthma per IQR increase in PM10 concentration was higher (3.9%; 95% CI, 1.2% to 6.7%) than in patients with no such history. CONCLUSIONS: Ambient air pollutants were positively associated with ED visits for asthma, especially among subjects with a prior history of allergic rhinitis or atopic dermatitis.

Susceptibility to ambient particulate matter on emergency care utilization for ischemic heart disease in Seoul, Korea.

Many epidemiological studies have reported associations between ambient particulate matter (PM) and cardiovascular diseases. However, the effects associated with PM that promote cardiovascular events among susceptible populations who may respond differently than the general population to the same ambient air pollutants remain unclear. We conducted a time-series study with generalized additive models to assess the association between ambient PM10 and emergency department (ED) visits for ischemic heart disease (IHD) in Seoul, Republic of Korea from 2005 to 2009. The ED data and previous medical records within the 5 years of each IHD event to examine the effect of PM10 in a susceptible population were obtained from Health Insurance Review and Assessment Service. Overall, the adjusted relative risks (RRs) of ED visits for IHD were not statistically significant for PM10, but significant positive RRs were found for groups with hypertension (1.018; 95 % confidence interval [CI] 1.002-1.035) and those who are ≥80 years of age (1.019; 1.002-1.037) for same-day exposure and with diabetes (1.019; 1.002-1.037) for single-lag models. Subgroup analyses revealed gender differences in ED visits for IHD in hypertensive patients and those who are ≥80 years of age; positive correlations were found only in males with the lag models. Our study suggests that ambient PM10 is significantly associated with ED visits for IHD, especially in males with hypertension, diabetes mellitus, or who are aged ≥80 years. Identification of populations susceptible to air pollution is of paramount importance to establishing recommendations or guidelines for high-risk individuals.