Search

Background: Dual-energy X-ray images (DEI) can distinguish or improve materials of interest in a two-dimensional radiographic image, by combining two images obtained from separate low and high energies. The concepts of DEI performance describing the performance of double-exposure DEI systems in the Fourier domain been previously introduced, however, the performance of double-exposure DEI itself in terms of various parameters, has not been reported.Materials and Methods: To investigate the DEI performance, signal-difference-to-noise ratio, modulation transfer function, noise power spectrum, and noise equivalent quanta were used. Low- and high-energy were 60 and 130 kVp with 0.01–0.09 mGy, respectively. The energyseparation filter material and its thicknesses were tin (Sn) and 0.0–1.0 mm, respectively. Noise-reduction (NR) filtering used the Gaussian-filter NR, median-filter NR, and anti-correlated NR.Results and Discussion: DEI performance was affected by Sn-filter thickness, weighting factor, and dose allocation. All NR filtering successfully reduced noise, when compared with the dual-energy (DE) images without any NR filtering.Conclusion: The results indicated the significance of investigating, and evaluating suitable DEI performance, for DE images in chest radiography applications. Additionally, all the NR filtering methods were effective at reducing noise in the resultant DE images.

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 (β = −0.020; bias-corrected (BC) 95% confidence interval (CI) = -0.047 to −0.006), frontal (β = −0.029; BC 95% CI = −0.063 to −0.005) and temporal (β = −0.022; BC 95% CI = −0.051 to −0.004) lobe cortical thickness, and hippocampal volume (β = −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 (β = −0.005; BC 95% CI = −0.012 to −0.001/β = −0.005; BC 95% CI = −0.013 to −0.001) and delayed recall for visual information (β = −0.005; BC 95% CI = −0.013 to −0.001/β = −0.005; BC 95% CI = −0.013 to −0.001). Additionally, the smaller the hippocampal volume, the lower the score in recognition memory (β = −0.005; BC 95% CI = −0.012 to −0.001), delayed recall for visual information (β = −0.005; BC 95% CI = −0.012 to −0.001), and verbal learning (β = −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.

Analyzing the economic value of the damage to human health caused by environmental risks has become an essential research focus, given the increasing necessity for effective decision-making. Since logical and rational analyses such as cost-benefit and cost-utility analyses will likely gain importance in future policymaking, the evaluation of economic costs becomes necessary. Among the various types of air pollutants, fine particulate matter (PM) is reported as closely related to mortality. To reduce result uncertainty by improving the methodology of risk assessment or the economic evaluation of fine PM, risk control measures are required for high-priority areas. This study addresses this issue by estimating the relative risk of PM2.5 while calculating the economic loss cost arising from acute death due to fine PM exposure in Seoul, Korea. The value of statistical life of one person's willingness to pay for mortality risk reduction is calculated to estimate the economic loss cost at each current level of exposure. The estimated economic loss cost due to all-cause mortality during 2016-2018 totaled approximately USD 1307.9 million per year; the costs of loss from respiratory and cardiovascular mortalities were USD 128.1 million per year and USD 426.9 million, respectively. Based on these results, this study concludes that the standards for PM2.5 are more effective than the ones established for PM10 in terms of economic value.

Conventional chest-radiography images are the most basic X-ray imaging system for diagnosing lung diseases. However, space-averaging increases due to the overlapping of anatomy structures as three-dimensional information are reduced in two-dimensions. A dual-energy X-ray imaging (DEI) technique for resolve space-averaging is used to increase the conspicuity of the lesion (i.e., lung nodule and calcification) by suppressing anatomical background noise. DEI techniques perform the weighted log-subtraction using the attenuation characteristics of the material for low- and high-kilovoltage-peak (kVp) X-rays. And the weighting factor is calculated to suppressing anatomical background. The objective of this research is to increase the lesion conspicuity in lung regions by optimizing DE technique parameters. DE technique has been applied to three phantoms mimicking the average, thick, and thicker adult chest thicknesses while maintaining the total incident dose equivalent to that used to obtain a single chest radiograph. Investigating DE technique parameters include the added filtration, the low- and high-kVp pair, and the dose allocation between low- and high-kVp setups at the total dose equal to or less than that of the conventional chest radiograph. And the DE image performances investigated through contrast-to-noise ratio, modulation-transfer function, noise-power spectrum, and detective quantum efficiency.

Aims This study aimed to elucidate the risk for stroke and systemic embolism (SE) in patients with atrial fibrillation and heart failure (HF) according to HF type. Methods and results A total of 10 780 patients with atrial fibrillation were enrolled in a multicentre prospective registry and divided according to HF type: no‐HF, HF with preserved ejection fraction (EF) (HFpEF), HF with mid‐range EF (HFmrEF), and HF with reduced EF (HFrEF). Each group included 237 age‐matched and sex‐matched patients (age, 69.0 ± 10.3 years; men, 69.6%). The baseline characteristics, cumulative incidence, and hazard ratios for stroke/SE and major bleeding were compared across the groups. Patients with HF accounted for 10.3% of the total population; HFpEF, HFmrEF, and HFrEF represented 43.7%, 23.6%, and 32.7% of the patients with HF, respectively. The CHA2DS2‐VASc score was significantly higher in the HFpEF, HFmrEF, and HFrEF groups than in the no‐HF group. The annual stroke/SE incidence rates were 2.8%, 0.7%, 1.1%, and 0.9% in the HFpEF, HFmrEF, HFrEF, and no‐HF groups, respectively. The cumulative incidence of stroke/SE was significantly highest in the HFpEF group at 22.8 ± 10.0 months (P = 0.020). The stroke/SE risk was higher in the HFpEF group than in the HFmrEF and HFrEF groups (hazard ratio, 3.192; 95% confidence interval, 1.039–9.810; P = 0.043). E/e' value was an independent risk factor for stroke/SE. There were no significant differences in the incidence of major bleeding across the groups. Conclusions The stroke/SE risk was the highest in the HFpEF group and comparable between the HFmrEF and HFrEF groups.

Design of a control structure in distillation columns involves selecting proper sets of manipulated and controlled variables (often including tray temperatures for inferential control of product compositions) and one-to-one pairing between the two sets. In this paper, various mathematical tools for achieving this goal are reviewed. First, traditional methods such as Singular Value Decomposition (SVD) and Relative Gain Array (RGA) that build upon a simplified steady-state or dynamic model of the column are explored. The role of optimization in systematizing the control design procedures is also investigated. Then, more recent inferential control techniques that rely on statistical methods such as Principal Component Regression (PCR), Partial Least Squares Regression (PLSR), and other machine learning techniques such as Artificial Neural Networks (ANN) and Support Vector Machine Regression (SVMR) are discussed extensively. The discussions include newer distillation technologies with complex configurations such as dividing-wall columns. Finally, the use of process simulators in aiding the control structure design of distillation columns is surveyed.

OBJECTIVE High blood pressure (BP) increases the risk of dementia; however, few studies have reported on the risk of dementia in patients with low-risk, early-grade hypertension. We investigated the protective effect of controlled BP on risk of dementia in treated, low-risk, grade 1 hypertensive patients from the entire National Health Insurance Service National Health Examinee cohort. METHODS We selected grade 1 hypertension (140-159/90-99 mmHg) patients with low risk, diagnosed in 2005-2006. All patients (N = 128 665) were classified into controlled (average BP

Background/Aims: Comparative occurrence of ischemic stroke for rhythm versus rate control strategy in patients with non-valvular atrial fibrillation (NVAF) is still inconclusive. The purpose of this study was to investigate whether the rhythm control strategy is associated with a lower risk of ischemic stroke compared to the rate control strategy in NVAF patients. Methods: The CODE-AF registry prospectively enrolled 6,280 consecutive pa tients who were treated for NVAF at 10 tertiary referral centers in South Korea. Of these, 2,513 NVAF patients (age, 67 ± 10 years; male, 61.8%) were clinically followed up for over 1-year and divided into rate and rhythm control groups. Results: Those treated with the rhythm control strategy were younger and had less proportions of underlying disease compared to those treated with the rate control strategy. After the propensity matching analysis, those treated with the rhythm control strategy had similar baseline characteristics including the CHA2DS2-VASC score compared to those treated with the rate control strategy. The rate of oral anticoagulation, all bleeding, and hospitalization were also simi larly between the two groups. The incidence rate of ischemic stroke in the rhythm control group was significantly lower than in the rate control group (0.7 vs. 6.9 per 1,000 person-years, p = 0.011). Conclusions: The rhythm control strategy demonstrated a beneficial effect to lower the risk of ischemic stroke during a 1-year follow-up compared to the rate control strategy.

BACKGROUND AND OBJECTIVES Ambient particulate matter (PM) in real urban air pollution (RUA) is an environmental health risk factor associated with increased cardiac events. This study investigated the threshold level to induce arrhythmia, as well as arrhythmogenic mechanism of RUA that mainly consisted of PM

PurposeDose reduction of non-vitamin K antagonist oral anticoagulants (NOACs) is indicated in patients with atrial fibrillation (AF) with renal impairment. This study investigated anticoagulation patterns and outcomes in patients with chronic kidney disease (CKD).Materials and methodsIn a prospective observational registry (CODE-AF), 3445 patients with non-valvular AF including 1129 with CKD (estimated glomerular filtration rate ≤ 60 mL min−1 1.73 m−2) were identified between June 1, 2016, and July 3, 2017.ResultsCompared with patients with no-CKD, patients with CKD more frequently had a high stroke risk (94.9% vs. 67.0%,p p p = 0.001) and rivaroxaban (0% vs. 79.5%,p = 0.001) were lower in patients with RIDR. However, the underdose rate of apixaban was not different (62.5% vs. 53.9%,p = 0.089). The overdose rate of dabigatran (7.5% vs. 0%) and rivaroxaban (13.7% vs. 0%) was higher in RIDR than in no-RIDR patients. Stroke/transient ischemic attack was significantly higher in CKD patients (1.4 vs. 0.6 per 100 person-years,p = 0.045). Aspirin significantly increased minor bleeding in CKD patients compared with controls (p = 0.037).ConclusionCKD patients might have a high stroke risk and NOAC usage rate. The underdose rate of NOACs decreased in CKD patients, except for apixaban. Aspirin significantly increased minor bleeding in CKD patients.

It is unknown whether heart failure (HF) with preserved ejection fraction (HFpEF) and HF with reduced ejection fraction (HFrEF) carry a similar risk of stroke or systemic embolism (SE) and other outcomes in patients with nonvalvular atrial fibrillation (AF). A prospective, multicenter outpatient registry with echocardiographic data which enrolled 10,589 patients from June 2016 to May 2019 was analyzed. In this registry, 935 (8.8%) patients had HF, and the proportions of patients with HFpEF and HFrEF were 43.2% and 56.8%, respectively. During follow-up over 1.33 years, 11 (2.07 per 100 person-years [PYR]) and 5 (0.76 per 100 PYR) patients had stroke/SE in the HFpEF and HFrEF groups, respectively, whereas 102 patients (0.84 per 100 PYR) had these sequelae in the no-HF group. The HFpEF group had a significantly higher cumulative incidence of stroke/SE (p = 0.004) and risk of stroke/SE (adjusted hazard ratio [HR] 2.23, 95% confidence interval [CI] 1.19 to 4.18) than the no-HF group. The risk of stroke/SE in the HFpEF group compared with that in the no-HF group was consistently increased even in patients on oral anticoagulation therapy (adjusted HR 2.55, 95% CI 1.31 to 4.96). There was a correlation between larger left atrial size and risk of stroke/SE (adjusted HR 1.53, 95% CI 1.03 to 2.29), but not between reduced left ventricular ejection fraction and this risk. In conclusion, these results suggest that strict oral anticoagulation therapy helps reduce the risk of stroke/SE in patients with nonvalvular AF and HFpEF, especially in those with a larger left atrial size.

Background/Aims: Efforts to reduce stroke in patients with atrial fibrillation (AF) have focused on increasing physician adherence to oral anticoagulant (OAC) guidelines; however, the high early discontinuation rate of vitamin K antagonists (VKAs) is a lim itation. Although non-VKA OACs (NOACs) are more convenient to administer than warfarin, their lack of monitoring may predispose patients to nonpersistence. We com pared the persistence of NOAC and VKA treatment for AF in real-world practice. Methods: In a prospective observational registry (COmparison study of Drugs for symptom control and complication prEvention of Atrial Fibrillation [CODE-AF] regis try), 7,013 patients with nonvalvular AF (mean age 67.2 ± 10.9 years, women 36.4%) were consecutively enrolled between June 2016 and June 2017 from 10 tertiary hospitals in Korea. This study included 3,381 patients who started OAC 30 days before enrollment (maintenance group) and 572 patients who newly started OAC (new-starter group). The persistence rate of OAC was evaluated. Results: In the maintenance group, persistence to OAC declined during 6 months, to 88.3% for VKA and 95.5% for NOAC (p < 0.0001). However, the persistence rate was not different among NOACs. In the new-starter group, persistence to OAC declined during 6 months, to 78.9% for VKA and 92.1% for NOAC (p < 0.0001). The persistence rate was lower for rivaroxaban (83.7%) than apixaban (94.6%) and edoxaban (94.1%, p < 0.001). In the new-starter group, diabetes, valve disease, and cancer were related to nonper sistence of OAC. Conclusions: Nonpersistence was significantly lower with NOAC than VKA in both the maintenance and new-starter groups. In only the new-starter group, apixaban or edox aban showed higher persistence rates than rivaroxaban.

Background: To characterize the course of Alzheimer’s disease (AD) over a longer time interval, we aimed to construct a disease course model for the entire span of the disease using two separate cohorts ranging from preclinical AD to AD dementia. Methods: We used longitudinal data from 127 participants with preclinical AD and 309 participants with mild cognitive impairments (MCI) due to AD from the Alzheimer’s Disease Neuroimaging Initiative. In order to develop a model of progression from preclinical AD to AD dementia, we estimated Alzheimer’s Disease Assessment Scale–Cognitive Subscale 13 (ADAS-cog 13) scores according to the follow-up time for each cohort, determined the time point at which the estimated scores of ADAS-cog 13 for the two cohorts first overlapped, and shifted the ADAS-cog 13 scores for the latter cohort at this time point to connect the two cohorts and to combine the data into a single unified progression course. Results: The estimated years for progression from the median ADAS-cog 13 score in the preclinical AD cohort (9.3 points) to the median ADAS-cog 13 score at the time of progression in the participants who progressed from preclinical AD to MCI due to AD (16.0 points) was 7.8 years. The estimated years for progression from preclinical AD to the median ADAS-cog 13 score at the time of progression in those who progressed from MCI to due AD to AD dementia (26.8 points) was 15.2 years. ADAS-cog 13 scores deteriorated most rapidly in female APOE ε4 carriers and most slowly in male APOE ε4 non-carriers ( p < 0.001). Conclusion: Our results suggest that disease progression modelling from preclinical AD to AD dementia may help clinicians to estimate where patients are in the disease course and provide information on variation in the disease course by sex and APOE ε4 status.

Individuals with atrial fibrillation (AF), especially women, have an increased risk of stroke and death. Although hormone replacement therapy (HRT) is widely used in postmenopausal women, the association between HRT use and AF risk is unclear. We aimed to investigate the association between various types of HRT and AF. This was a population-based retrospective cohort study from The Korean National Health Insurance Service-National Sample Cohort (2004–2015). Participants were aged 45–60 years and were free from cardiovascular disease and AF at baseline. Overall, 13,452 (64.03%) women had never received HRT, 5671 (26.99%) had received HRT, and 1885 (8.98%) were currently receiving HRT. In multivariable analysis, the relative hazards for AF were significantly higher among current users (p < 0.001) and lower among past users (p = 0.069). Current users—except those using estradiol-only HRT—had significantly elevated AF risk. Among past users, only estradiol plus progestin HRT users had a reduced AF risk after adjusting for covariates (p = 0.027). Ongoing HRT posed an increased risk of AF. The degree of risk varied based on the specific type of estrogen and progestins co-administration. These findings indicate that, with respect to AF risk, oral estradiol-containing HRT is superior to HRT containing oral conjugated equine estrogen or tibolone.

Polycyclic aromatic hydrocarbons (PAHs) are formed during incomplete combustion of organic matter, and firefighters are highly exposed to these toxic compounds at fire sites. Exposure to PAHs can cause cognitive decline and neurodegeneration; however, to date, few studies have examined the potential effects of PAH exposure on structural changes in the brain. We aimed to investigate the association between the four types of PAH metabolites and the corresponding changes in neuroimaging markers based on smoking status and hypertension in male firefighters. For this, we utilized the 2-year follow-up data of 301 Korean male firefighters aged over 40 years. The concentrations of four PAH metabolites in urine were measured. Subcortical volume and cortical thickness were estimated using 3 T magnetic resonance imaging of the brain. A generalized linear model was used to investigate the effects of PAHs on changes in the subcortical volume and cortical thickness. We found an association between 1-hydroxyphenathrene (1-OHPHE) and 2-hydroxyfluorene (2-OHF) and changes in several brain regions in all the study participants. Individuals who had never smoked showed significantly thinner frontal (p < 0.001), parietal (p < 0.001), temporal (p < 0.001), and cingulate lobes (p < 0.001) with 1% increase each in the urinary concentration of 1-OHPHE. Hypertension interacted with the concentration of 1-OHPHE to reduce the volume of gray matter and cause cortical thinning in the frontal, parietal, and temporal lobes. Exposure to PAHs may reduce cortical thickness and subcortical volume, which are definitive markers of neurodegeneration. Notably, hypertension can accelerate the degenerative effects of PAHs.

Magnetic domain wall (DW) motion in perpendicularly magnetized materials is drawing increased attention due to the prospect of new type of information storage devices, such as racetrack memory. To augment the functionalities of DW motion‐based devices, it is essential to improve controllability over the DW motion. Other than electric current, which is known to induce unidirectional shifting of a train of DWs, an application of in‐plane magnetic field also enables the control of DW dynamics by rotating the DW magnetization and consequently modulating the inherited chiral DW structure. Applying an external bias field, however, is not a viable approach for the miniaturization of the devices as the external field acts globally. Here, the programmable exchange‐coupled DW motion in the antiferromagnet (AFM)/ferromagnet (FM) system is demonstrated, where the role of an external in‐plane field is replaced by the exchange bias field from AFM layer, enabling the external field‐free modulations of DW motions. Interestingly, the direction of the exchange bias field can also be reconfigured by simply injecting spin currents through the device, enabling electrical and programmable operations of the device. Furthermore, the result inspires a prototype DW motion‐based device based on the AFM/FM heterostructure, that could be easily integrated in logic devices., The role of magnetic field in the ferromagnetic domain‐wall (DW) motions within a micropatterned magnetic layer can be efficiently overtaken by the effective field from adjacent exchange‐coupled antiferromagnet. Using the spin structure of antiferromagnet controllable with spin current, highly adjusted motion of exchange‐coupled DW is demonstrated showing a prospect of field‐free electrical operations of DW‐based spintronics devices.

BackgroundDespite emerging evidence suggesting that visceral fat may play a major role in obesity-induced neurodegeneration, little evidence exists on the association between visceral fat and brain cortical thickness in the elderly.PurposeWe aimed to examine the association between abdominal fat and brain cortical thickness in a Korean elderly population.MethodsThis cross-sectional study included elderly individuals without dementia (n = 316). Areas of visceral fat and subcutaneous fat (cm2) were estimated from computed tomography scans. Regional cortical thicknesses (mm) were obtained by analyzing brain magnetic resonance images. Given the inverted U-shaped relationship between visceral fat area and global cortical thickness (examined using a generalized additive model), visceral fat area was categorized into quintiles, with the middle quintile being the reference group. A generalized linear model was built to explore brain regions associated with visceral fat. The same approach was used for subcutaneous fat.ResultsThe mean (standard deviation) age was 67.6 (5.0) years. The highest quintile (vs. the middle quintile) group of visceral fat area had reduced cortical thicknesses in the global [β = –0.04 mm, standard error (SE) = 0.02 mm, p = 0.004], parietal (β = –0.04 mm, SE = 0.02 mm, p = 0.01), temporal (β = –0.05 mm, SE = 0.02 mm, p = 0.002), cingulate (β = –0.06 mm, SE = 0.02 mm, p = 0.01), and insula lobes (β = –0.06 mm, SE = 0.03 mm, p = 0.02). None of the regional cortical thicknesses significantly differed between the highest and the middle quintile groups of subcutaneous fat area.ConclusionThe findings suggest that a high level of visceral fat, but not subcutaneous fat, is associated with a reduced cortical thickness in the elderly.

Purpose Dementia is an important health issue in Korea due to its associated medical costs. Our study aimed to estimate the prevalence of dementia in Korea by analyzing hospital utilization rates. Materials and methods We examined National Health Insurance data from 2008 to 2016 and identified all dementia cases. Crude and ageand sex-standardized prevalence were calculated. A generalized linear mixed model was used to estimate prevalence ratios. Results We identified 176746 and 530269 dementia cases in 2008 and 2016, respectively. Alzheimer's disease was the most common dementia subtype (65.4% and 86.1% in 2008 and 2016, respectively). Across all age groups, the prevalence of dementia increased consistently: the increase was prominent among patients ≥85 years of age. Among patients ≥65 years of age, crude prevalence was estimated at 31.3 and 72.2 per 1000 population in 2008 and 2016, respectively. Age- and sex-standardized prevalence increased from 31.3 to 62.0 per 1000 population between 2008 and 2016, respectively. The prevalence ratio for dementia in 2016 was 2.02 times (95% confidence interval, 2.01-2.03) higher than that in 2008. When adjusted for age, dementia was more prevalent among females. The most common comorbidity was hypertension, followed by diabetes and stroke. Conclusion Our results demonstrated that hospital utilization for dementia increased significantly from 2008 to 2016, reflecting a proportional increase in the prevalence of dementia. Korean healthcare policy must prioritize dementia treatment.

Objectives It is well-known that post-traumatic stress disorder (PTSD) among firefighters contributes to their job-related stress. However, the relationship between burnout and PTSD in firefighters has rarely been studied. This study therefore explored the association between burnout and its related factors, such as trauma and violence, and PTSD symptoms among firefighters in Korea. Methods A total of 535 firefighters participated in the Firefighter Research on Enhancement of Safety a Health study at 3 university hospitals from 2016 to 2017. The 535 participants received a baseline health examination, including questionnaires assessing their mental health. A Web-based survey was also conducted to collect data on job-related stress, history of exposure to violence, burnout, and trauma experience. The associations among burnout, its related factors, and PTSD symptoms were investigated using structural equation modeling. Results Job demands (β=0.411, pl0.001) and effort-reward balance (β=-0.290, pl0.001) were significantly related to burnout. Burnout (β=0.237, pl0.001) and violence (β=0.123, p=0.014) were significantly related to PTSD risk. Trauma (β=0.131, p=0.001) was significantly related to burnout; however, trauma was not directly associated with PTSD scores (β=0.085, p=0.081). Conclusions Our results show that burnout and psychological, sexual, and physical violence at the hands of clients directly affected participants' PTSD symptoms. Burnout mediated the relationship between trauma experience and PTSD.

Epidemiological studies have revealed associations between the fine particle (PM2.5; aerodynamic diameter2.5 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.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.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).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.

An overview is given of the soft X-ray photon-in/photon-out instruments on the free-electron laser (FEL) beamline at the Pohang Accelerator Laboratory, and selected commissioning results are presented. The FEL beamline provides a photon energy of 270 to 1200 eV, with an energy bandwidth of 0.44%, an energy of 200 µJ per pulse and a pulse width of 2O3(100) have been obtained and the performance of the spectrometer has been evaluated.

Natural gas (NG) is an environment-friendly energy source with low CO2 and SOx emission. NG is usually liquefied during processing for transportation and storage, and then vaporized before consumption for multiple purposes. Usually, cold energy from the vaporization process is not utilized and hence wasted. One of the means of utilizing the cold energy is Organic Rankine Cycle (ORC), through which electricity can be generated from any grade of heat sources. Accordingly, ORC has been extensively investigated with the aim of increasing efficiency. However, although the ORC process has high potential risk of fatality, the safety aspect has not been previously studied. In this study, ORC design considering the thermodynamic and safety aspects is explored with a multi-objective optimization methodology. Exergy efficiency is used for the thermodynamic aspect, and risk distance is used for the safety aspect, with inherent safety techniques for designing safer processes in the conceptual design. Considering the working fluid as the main factor for optimal ORC design, six working fluids in three categories (pure component, binary components, ternary components) are investigated. Pareto optimal solutions are obtained from the multi-objective optimization method with two objectives based on working fluids for ORC design. Optimization variables include working condition (pressure), working fluid conditions (components). Moreover, the final optimal solution is selected using decision techniques, such as LINMAP and TOPSIS.

This paper examines the current status of the auto parts industry by creating the Auto Parts Imports Intensity Index. COMTRADE data from 2000 to 2017 was used for imports of automotive and auto parts to see how imports of finished car and auto parts have different interdependent relationships in specific countries. Two categories were selected for international comparison; the first category includes automotive manufacturing developing countries such as China, India, Indonesia and Russia. And the second category includes developing countries that just import cars, which are typically Middle East Countries. The results found that direct exports from Korea shows a weakening trend over-all. The decreasing sales growth of automobiles brings the high values of index specially in Chinese market. In contrast, the index value shows balanced pattern in most of countries for German cars. The different patterns between Korea and Germany can be partially explained by the excessive vertical industry structure of Korea and empowering SMEs of Germany. Implications are the following; first, the government should support SMEs to enhance their capabilities like German SMEs. Second, opportunities for auto parts industries are still strongly present. As developing countries in the first category increase their local production, the demand for reliable low-cost car parts has also increased. Therefore, Korean auto parts SMEs should explore these possibilities through the inclusion to global value chain. As for the second category, targeted efforts to diversify markets are required.

A method for designing the optimal working fluid mixture of organic Rankine cycles (ORC), which is robust against uncertainty in its composition, is developed. The objective function for designing ...

The government of the Republic of Korea (ROK) has established relevant laws and a master plan for infectious disease control and prevention based on their experiences with past epidemics. In addition, the Ministry of Health and Welfare has designed a standard manual for risk management that involves pan-governmental crisis management systems. This national infectious disease management system is constantly being supplemented and developed in face of infectious disease-related crises. In this study, we set out to present directions for infectious disease prevention and flow of management and governance between central and local governments to ensure systematic quarantine activities in the ROK. During the coronavirus disease 2019 (COVID-19) pandemic, public-private partnerships have been established to collect, provide, process, and disseminate information for effective quarantine. This has enabled the development and rapid approval of test kits, the tracking of cases, and the allocation of appropriate resources for patient treatment. Additionally, the Infectious Disease Control Agency has actively utilized information and communication technology platforms to disclose information necessary in real-time for COVID-19 quarantine and management. Overall, these efforts have played an important role in epidemiological investigations, patient management, and quarantine in the early stages of the COVID-19 pandemic.

Alcohol, a known addictive substance, affects the structural properties of the brain. In this study, we explored associations between alcohol use and gray matter properties among firefighters, who are often exposed to significant occupational stress.Gray matter volume (GMV) was evaluated using voxel-based morphometry in 287 male firefighters (mean age: 48.8 ± 7.7 years). Firefighters were classified into 32 never-drinkers, 162 non-heavy alcohol users, and 93 heavy alcohol users according to their alcohol consumption. GMV was compared between groups, and the correlations between GMV and alcohol use were investigated. A voxel-wise height threshold of p 0.001 (uncorrected) was used, with small volume correction applied on cluster level.Heavy alcohol users had lower GMV in the bilateral thalamus than non-heavy alcohol users or never-drinkers. Heavy alcohol users also showed lower GMV in the left insula, compared to other groups. The higher the alcohol consumption among firefighters, the lower the GMV of the right thalamus.The results of this study show that heavy alcohol use has an association with lower GMV in several core regions, including the thalamus. When considering the impact of these brain regions on cognitive and behavioral control, our findings suggest a need for concern about heavy alcohol use among firefighters.

OBJECTIVES We aim to compare the trends of non-communicable diseases (NCDs) and death among people living with HIV (PLWH) and uninfected controls in South Korea. METHODS We identified PLWH from a nationwide database of all Korean citizens enrolled from 1 January 2004 to 31 December 2016. A control cohort was randomly selected for PLWH by frequency matching for age and sex in a 20:1 ratio. To compare NCD trends between the groups, adjusted incidence rate ratios for outcomes across ages, calendar years and times after HIV diagnosis were calculated. RESULTS We included 14 134 PLWH and 282 039 controls in this study; 58.5% of PLWH and 36.4% of the controls were diagnosed with at least one NCD. The incidence rates of cancers, chronic kidney disease, depression, osteoporosis, diabetes and dyslipidaemia were higher in PLWH than in the controls, whereas those of cardiovascular disease, heart failure, ischaemic stroke and hypertension were lower in PLWH. Relative risks (RRs) for NCDs in PLWH were higher than controls in younger age groups. Trends in the RRs of NCDs tended to increase with the calendar year for PLWH vs. controls and either stabilized or decreased with time after HIV diagnosis. The RR of death from PLWH has decreased with the calendar year, but showed a tendency to rise again after 2014 and was significant at the early stage of HIV diagnosis. CONCLUSIONS Although the RR of each NCD in PLWH showed variable trends compared with that in controls, NCDs in PLWH have been increasingly prevalent.

Background Firefighters inevitably encounter emotionally and physically stressful situations at work. Even firefighters without diagnosed post-traumatic stress disorder receive clinical attention because the nature of the profession exposes them to repetitive trauma and high occupational stress. This study investigated gray matter abnormalities related to high occupational stress in firefighters using voxel-based morphometry (VBM) and surface-based morphometry (SBM). Methods We assessed 115 subjects (112 males and 3 females) using magnetic resonance imaging and evaluated occupational stress by the Korean Occupational Stress Scale-26 (KOSS-26). Subjects were classified into highly or lowly stressed groups based on the median value of the KOSS-26. Results In VBM analysis, we found that firefighters with high occupational stress had lower gray matter volume (GMV) in both sides of the insula, the left amygdala, the right medial prefrontal cortex (mPFC), and the anterior cingulate cortex than firefighters with low occupational stress. In SBM analysis based on regions of interest, the GMV of the bilateral insula and right mPFC were also lower in the highly stressed group. Within the highly stressed group, low GMV of the insula was significantly correlated with the length of service (left: r = −0.347, P = 0.009; right: r = −0.333, P = 0.012). Conclusion Our findings suggest that regional GMV abnormalities are related to occupational stress. Regional gray matter abnormalities and related emotional dysregulation may contribute to firefighter susceptibility to burnout., Graphical Abstract

To investigate the behavior of various steel anchors, push-out tests were performed for 13 test specimens. Test parameters included the geometry of beams (wide-flange beams and composite beams) and the type of steel anchors (stud anchors and Z- and C-channel anchors with full- or partial-length welding). Test results showed that the performance of test specimens strongly depends on the types of steel anchors rather than the geometry of steel beams. The specimens with C-channel anchors showed the highest load-carrying capacity but the most drastic load reduction after the peak load. The specimens with Z-channel anchors showed a similar behavior to those with C-channel anchors but the load reduction occurred at a slightly slower rate. The load-carrying capacity was increased with the length of the Z- and C-channel anchors. The specimens with stud anchors reached the peak load at a slow rate and showed the most ductile behavior. The test results were compared with predictions by various design equations for steel anchors available in the literature, and the existing design equations for channel anchors with partial-length welding were considered applicable to design.

Preschool children aged 3-6 years are vulnerable to exposed to particulate matter ("PM10" and "PM2.5"). It is required in evaluating the risk based on dose of preschool children. Microenvironments which preschool children mainly visited were classified. Inhalation type was adapted in each microenvironment in consideration of intensity of activity. The exposure scenario was described as preschool children had been living in Seoul, South Korea, and dose was calculated by considering time-activity-pattern with major microenvironments and inhalation type of preschool children for 24 h. Monte-Carlo simulation technique is used to estimate dose of particulate matter in probabilistic distribution by age and sex. The contribution of exposure by microenvironments and inhalation type was calculated. Risk assessment was performed based on WHO interim target-3 24-h concentration in order to estimate. Sensitivity analysis was performed to determine the effective variable of dose. As a result of the study, the dose of PM was higher for boys than girls and tended to decrease with age. The overall contributions of PM doses by microenvironments were daycare center, home, other facilities, transit, and outdoors, respectively, although differed between daycare center and home priority by age and sex. Especially, the contribution of daycare center and home was very high, accounting over 85% of the total. The overall contributions of PM doses by inhalation type were "run," "stable," "sleep," and "walk inhalation," respectively. The results of hazard quotient showed that "PM10" exceeded the WHO interim target-3 24-h concentration standard by about 10% and "PM2.5" exceeded about half. Through sensitivity analysis, PM concentration was confirmed as a major influence variable for doses. This study was able to affirm the overall exposure status of "PM10" and "PM2.5" for preschool children, and this is expected to be used in regulation and public health.

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

Plant breeding has a long history of developing new varieties that have ensured the food security of the human population. During this long journey together with humanity, plant breeders have successfully integrated the latest innovations in science and technologies to accelerate the increase in crop production and quality. For the past two decades, since the completion of human genome sequencing, genomic tools and sequencing technologies have advanced remarkably, and adopting these innovations has enabled us to cost down and/or speed up the plant breeding process. Currently, with the growing mass of genomic data and digitalized biological data, interdisciplinary approaches using new technologies could lead to a new paradigm of plant breeding. In this review, we summarize the overall history and advances of plant breeding, which have been aided by plant genomic research. We highlight the key advances in the field of plant genomics that have impacted plant breeding over the past decades and introduce the current status of innovative approaches such as genomic selection, which could overcome limitations of conventional breeding and enhance the rate of genetic gain.

Background Recent evidence suggests that neurological health could be improved with the intervention of local green space. A few studies adopted cortical thickness, as an effective biomarker for neurodegenerative disorder, to investigate the association with residential greenness. However, they relied on limited data sources, definitions or applications to assess residential greenness. Our cross-sectional study assessed individual residential greenness using an alternative measure, which provides a more realistic definition of local impact and application based on the type of area, and investigated the association with cortical thickness. Methods The study population included 2542 subjects who participated in the medical check-up program at the Health Promotion Center of the Samsung Medical Center in Seoul, Korea, from 2008 to 2014. The cortical thickness was calculated by each of the four and global lobes from brain MRI. For greenness, we used the enhanced vegetation index (EVI) that detects canopy structural variation by adjusting background noise based on satellite imagery data. To assess individual exposure to residential greenness, we computed the maximum annual EVI before the date of a medical check-up and averaged it within 750 m from subjects' homes to represent an average walking distance. Finally, we assessed the association with cortical thickness by urban and non-urban populations using multiple linear regression adjusting for individual characteristics. Results The average global cortical thickness and EVI were 3.05 mm (standard deviation = 0.1 mm) and 0.31 (0.1), respectively. An interquartile range increase in EVI was associated with 11 μm (95% confidence interval = 3–20) and 9 μm (1–16) increases in cortical thickness of the parietal and occipital regions among the urban population. We did not find associations in non-urban subjects. Conclusions Our findings confirm the association between residential greenness and neurological health using alternative exposure assessments, indicating that high exposure to residential greenness can prevent neurological disorders.

In February 2018, the Ministry of Food and Drug Safety in Korea approved tenofovir disoproxil fumarate and emtricitabine (TDF/FTC) co-formulate for use in pre-exposure prophylaxis (PrEP) for the prevention of human immunodeficiency virus (HIV) infection. This study aimed to estimate the cost-effectiveness of PrEP in men who have sex with men (MSM), a major risk group emerging in Korea. A dynamic compartmental model was developed for HIV transmission and progression in MSM aged 15–64 years. With a combined model including economic analysis, we estimated averted HIV infections, changes in HIV prevalence, discounted costs, quality-adjusted life-years (QALYs), and incremental cost-effectiveness ratios (ICERs). PrEP was evaluated in both the general MSM and high-risk MSM populations and was assumed to reduce infection risk by 80%. Implementing PrEP in all MSM would avert 75.2% HIV infections and facilitate a gain of 37,372 QALYs at a cost of $274,822 per QALY gained over 20 years relative to the status quo. Initiating PrEP in high-risk MSM with an average of eight partners per year (around 20% of MSM) would improve the cost-effectiveness, averting 78.0% HIV infections and add 29,242 QALYs at a cost of $51,597 per QALY gained, which is within the willingness-to-pay threshold for Korea of $56,000/QALY gained. This result was highly sensitive to annual PrEP costs, quality-of-life for people who are on PrEP, and initial HIV prevalence. Initiating PrEP in a larger proportion of MSM in Korea would prevent more HIV infections, but at an increasing cost per QALY gained. Focusing PrEP on higher risk MSM and any reduction in PrEP cost would improve cost-effectiveness.

Background Air pollution is a risk factor for depression or depressive symptoms. However, few studies have examined an effect modifier as a protective factor against depressive symptoms associated with air pollution, including social support. Notably, less is known about a married relationship in the association between exposure to air pollution and depressive symptoms among the elderly. Methods This study included 2122 marrieds and 607 non-marrieds, recruited in 2014–2017 from different regions of South Korea. Depressive symptoms were measured by the Korean version of the Geriatric Depression Scale Short Form (SGDS-K). After adjustment for potential confounders using propensity score of being assigned to the marrieds, we examined the extent of whether the effects of exposure to air pollutants (PM10, PM2.5, and NO2) on depressive symptoms were different between marrieds and non-marrieds. Subgroup analyses by gender and residence area were also performed. Results Marrieds than non-marrieds were less likely to have depressive symptoms and had smaller SGDS-K associated with increased exposure to PM10 and PM2.5 concentrations, respectively. After stratification of subjects by gender and residence area, the interaction term appeared to be significant among men and the non-metropolitan group, indicating the protective effect of married relationships on depressive symptoms attributable to air pollution exposure in them. Limitations Although we adjusted the propensity score, our findings might be confounded by the contextual effect associated with married relationships. Conclusions A married relationship, as a social tie, may attenuate the effect of exposure to air pollution on depressive symptoms among the elderly. Nonetheless, additional research is worthwhile to explore the extent of other social relationships in the association between air pollution exposure and depressive symptoms.

Objective No long-term follow-up study has investigated the effect of blood pressure (BP) on cardiovascular disease mortality and morbidity in firefighters. To investigate the effects of BP on the risk of major adverse cardiovascular events (MACEs) using a national representative population-matched cohort. Methods We enrolled all firefighters (N = 8242) and 28 678 referent controls aged more than 40 years who underwent baseline health examinations in 2002 and 2003. Records of hospitalization and mortality until 2015 were checked. To evaluate the causal effect of BP on MACE, subcohort analysis using a propensity score-matched (PSM) cohort with respect to job classification (firefighter vs. control) was performed. Results Hypertension significantly increased the risk of MACEs compared with normal BP in both firefighters and the age--sex matched cohort, but in participants with elevated BP, significantly increased risk of MACEs [hazards ratio 1.41, 95% confidence interval (CI) 1.06-1.88] was observed only among firefighters. In the PSM cohort, firefighters had a significantly higher risk of death or hospitalization from MACEs (hazard ratio 1.29, 95% CI 1.14-1.47), myocardial infarction (hazard ratio 1.24, 95% CI 1.07-1.43), and ischemic stroke (hazard ratio 1.43, 95% CI 1.12-1.82) than controls. Firefighters with elevated BP (hazard ratio 1.58, 95% CI 1.04-2.40), stage 1 (hazard ratio 1.24, 95% CI 1.00-1.52), and stage 2 (hazard ratio 1.39, 95% CI 1.13-1.71) hypertension had higher risk of MACEs than PSM controls. Conclusion Firefighters showed significantly higher cardiovascular risk than referent controls when comparing those within the same BP category, suggesting that firefighters with elevated BP and hypertension may be at high risk of adverse prognosis.

Background Symptom burden is an important factor in determining the treatment of atrial fibrillation (AF). AF is frequently accompanied by heart failure (HF). This study investigated the characteristics of AF symptoms with concomitant HF. Methods A total of 4885 patients with AF were consecutively enrolled through a prospective observational registry (the Comparison Study of Drugs for Symptom Control and Complication Prevention of Atrial Fibrillation [CODE-AF] registry). Clinically diagnosed HF was divided into three categories (preserved, mid-range, and reduced ejection fraction [EF]). Symptom severity was assessed using the European Heart Rhythm Association (EHRA) classification. Results The presence of AF-related symptoms was comparable irrespective of concomitant HF. Patients with HF with reduced EF demonstrated severe (EHRA classes 3 and 4) and atypical symptoms. HF with preserved EF was also associated with atypical symptoms. Female sex and AF type were associated with the presence of symptoms in AF without HF, and non-maintenance of sinus rhythm and increased left atrial pressure (E/e′ ≥ 15) were factors related to the presence of symptoms in AF with HF. Conclusion AF with concomitant HF presented with more severe and atypical symptoms than AF without HF. Maintaining the sinus rhythm and reducing the E/e’ ratio are important factors for reducing symptoms in AF with concomitant HF.

Accessibility of emergency medical care is one of the crucial factors in evaluating national primary medical care systems. While many studies have focused on this issue, there was a fundamental limit to the measurement of accessibility of emergency rooms, because the commonly used census-based population data are difficult to provide realistic information in terms of time and space. In this study, we evaluated the geographical accessibility of emergency rooms in South Korea by using dynamic population counts from mobile phone data. Such population counts were more accurate and up-to-date because they are obtained by aggregating the number of mobile phone users in a 50-by-50 m grid of a locational field, weighted by stay time. Considering both supply and demand of emergency rooms, the 2-step floating catchment analysis was implemented. As a result, urban areas, including the capital city Seoul, showed lower accessibility to emergency rooms, whereas rural areas recorded higher accessibility. This result was contrary to the results analyzed by us based on census-based population data: higher accessibility in urban areas and lower in rural. This implies that using solely census data for accessibility analysis could lead to certain errors, and adopting mobile-based population data would represent the real-world situations for solving problems of social inequity in primary medical care.

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.

Process monitoring is an important aspect of safe operation of process plants. Various methods exist that monitor the process using data-driven methods, but they all have certain limitations. For i...

Background/Aim: Given a fast-growing aging population in South Korea, the prevalence of cognitive impairment in elderly is increasing. Despite growing evidence of air pollution exposure as one of the risk factors for declining cognition, few studies have been conducted on gender difference in the relation of cognitive function associated with outdoor air pollution. The aim of this study is to investigate the effect modification of gender difference in the association between cognitive function and air pollutant exposure (PM10, PM2.5-10, and NO2). Methods: The study focused on elderly, and the resulting sample included 1,484 participants aged 55 and older with no neurologic diseases, recruited from the four regions in Korea (Seoul, Incheon, Pyeongchang, and Wonju). We used the Mini-Mental State Examination (MMSE) score (with the conventional cut-off point "23-24") to assess cognitive decline as the primary outcome of the study. Air pollution data used in this study were based on the 5-year average of predicted PM10 and NO2 concentrations, as well as the 2015 average PM2.5 concentration. Additionally, a survey questionnaire was utilized to obtain information about general health assessment. To explore gender differences in the effects of air pollution exposure on cognitive function, we used penalized logistic regression, negative binomial regression, and generalized linear mixed model analyses. Subgroup analyses were also performed by the geographic location of residence (metropolitan vs. non-metropolitan). Results: We found that women than men had a higher risk for decreased cognitive function associated with increased exposure to PM10 and PM2.5-10, respectively, even after adjustments for confounding factors (OR 1.01 [95%CI 1.00-1.03] in PM10; OR 1.03 [95%CI 1.01-1.07] in PM2.5-10). After stratification by metropolitan status, we also found that the adverse effect of NO2 exposure on cognitive function was higher in women than men [OR 1.02 [95%CI 1.00-1.05] in metropolitan; OR 1.12 [95%CI 1.04-1.20] in non-metropolitan]. Notably, the magnitude of the effect sizes was greater among those in non-metropolitan regions than metropolitan ones. Conclusions: Although our findings suggest that the adverse effects of outdoor air pollution on cognitive function appeared to be higher in women than men, this should be tentatively reflected due to some limitations in our results. While additional research is warranted to confirm or dispute our results, our findings suggest an indication of the need for developing and implementing prevention or interventions with a focus on elderly women with increased risk for air pollution exposure.

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.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.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 (β = -0.03, P = .02), parietal (β = -0.04, P = .01), temporal (β = -0.06, P .001), and insular lobes (β = -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 (β = -0.03, P = .006) and parietal lobes (β = -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.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.