Immunoregulatory role of the gut microbiota in inflammatory depression.

Inflammatory depression is a treatment-resistant subtype of depression. A causal role of the gut microbiota as a source of low-grade inflammation remains unclear. Here, as part of an observational trial, we first analyze the gut microbiota composition in the stool, inflammatory factors and short-chain fatty acids (SCFAs) in plasma, and inflammatory and permeability markers in the intestinal mucosa of patients with inflammatory depression (ChiCTR1900025175). Gut microbiota of patients with inflammatory depression exhibits higher Bacteroides and lower Clostridium, with an increase in SCFA-producing species with abnormal butanoate metabolism. We then perform fecal microbiota transplantation (FMT) and probiotic supplementation in animal experiments to determine the causal role of the gut microbiota in inflammatory depression. After FMT, the gut microbiota of the inflammatory depression group shows increased peripheral and central inflammatory factors and intestinal mucosal permeability in recipient mice with depressive and anxiety-like behaviors. Clostridium butyricum administration normalizes the gut microbiota, decreases inflammatory factors, and displays antidepressant-like effects in a mouse model of inflammatory depression. These findings suggest that inflammatory processes derived from the gut microbiota can be involved in neuroinflammation of inflammatory depression.

Impacts of emissions and meteorological conditions in three different phases of aerosol pollution during 2013-2022 in Anhui, China.

The PM2.5 concentrations in Anhui, which links the Yangtze River Delta region, China's fastest growing economy area, with the Beijing-Tianjin-Hebei (BTH) region, China's most polluted region, are influenced not only by emissions, but also by variation of meteorological conditions. A comprehensive understanding of the relative impacts of meteorology and emissions on heavy pollution in Anhui at three phases (i.e., phase1: from 2013 to 2017; phase2: from 2018 to 2020; phase 3: from 2021 to 2022) from 2013 to 2022, which can provide suggestions for pollution prevention and control in the future. The decrease in pollutant concentrations from 2013 to 2022 is mainly attributed to the continued reduction in emissions, while the year-to-year fluctuations in pollutant concentrations are largely influenced by meteorological conditions. Although emissions are decreasing, the proportions of residential biofuel combustion and cement are increasing. In addition to the effects of prevailing northeasterly and northwesterly winds (i.e., Type1 and Type2), there is also concern about the influences of static weather and neighboring regional transport (i.e., Type5 and Type6), especially in 2016. The contribution of emissions is greater in phase 2 and phase 3, with a 17 % increase compared to phase 1. Overall, approximately 57 % of explosive growth in PM2.5 concentration during the cumulative stage (CS) can be regarded as the feedback effect of the deteriorating meteorological conditions. Therefore, statistical analyses show that limiting PM2.5 concentrations below about 73 µg m-3 would weaken the feedback effects, which in turn would avoid most of the explosive growth processes in the CS of the 60 heavy pollution processes, which can provide a reference for the government to set a target for sustained emission reduction.

The impact of workplace violence on job burnout among Chinese correctional officers: the chain mediating effects of stress and insomnia.

BACKGROUND: The risk of workplace violence and job burnout among Chinese correctional officers is high. Stress and insomnia may influence the relationship between workplace violence and job burnout; however, this influence has been rarely studied. This study aimed to explore the effect of workplace violence on job burnout among Chinese correctional officers and to assess the contribution of stress and insomnia to this effect. METHODS: In this study, the workplace violence scale, the Assens insomnia scale, the 21-item Depression Anxiety Stress Scale, and the Maslach Burnout Inventory-General Survey scale were used to assess the workplace violence, insomnia, stress, and job burnout experienced by the 472 correctional officers, respectively. RESULTS: The results showed that (1) workplace violence was significantly and positively predictive of job burnout, (2) workplace violence affected job burnout through the mediation of stress, (3) workplace violence affected job burnout through the mediation of insomnia, and (4) stress and insomnia played fully interlocking mediating roles in the effect of workplace violence on job burnout. CONCLUSION: Stress and insomnia may play a full mediating role in the relationship between workplace violence and job burnout. This suggested that correctional officers may take measures to reduce stress and improve insomnia, thereby reducing their job burnout. Further research may focus on the development of effective interventions to reduce stress and improve insomnia among correctional officers.

Gut microbiota composition in depressive disorder: a systematic review, meta-analysis, and meta-regression.

Studies investigating gut microbiota composition in depressive disorder have yielded mixed results. The aim of our study was to compare gut microbiome between people with depressive disorder and healthy controls. We did a meta-analysis and meta-regression of studies by searching PubMed, Web of Science, Embase, Scopus, Ovid, Cochrane Library, ProQuest, and PsycINFO for articles published from database inception to March 07, 2022. Search strategies were then re-run on 12 March 2023 for an update. We undertook meta-analyses whenever values of alpha diversity and Firmicutes, Bacteroidetes (relative abundance) were available in two or more studies. A random-effects model with restricted maximum-likelihood estimator was used to synthesize the effect size (assessed by standardized mean difference [SMD]) across studies. We identified 44 studies representing 2091 patients and 2792 controls. Our study found that there were no significant differences in patients with depressive disorder on alpha diversity indices, Firmicutes and Bacteroidetes compared with healthy controls. In subgroup analyses with regional variations(east/west) as a predictor, patients who were in the West had a lower Chao1 level (SMD -0.42[-0.74 to -0.10]). Subgroup meta-analysis showed Firmicutes level was decreased in patients with depressive disorder who were medication-free (SMD -1.54[-2.36 to -0.72]), but Bacteroidetes level was increased (SMD -0.90[0.07 to 1.72]). In the meta-regression analysis, six variables cannot explain the 100% heterogeneity of the studies assessing by Chao1, Shannon index, Firmicutes, and Bacteroidetes. Depleted levels of Butyricicoccus, Coprococcus, Faecalibacterium, Fusicatenibacter, Romboutsia, and enriched levels of Eggerthella, Enterococcus, Flavonifractor, Holdemania, Streptococcus were consistently shared in depressive disorder. This systematic review and meta-analysis found that psychotropic medication and dietary habit may influence microbiota. There is reliable evidence for differences in the phylogenetic relationship in depressive disorder compared with controls, however, method of measurement and method of patient classification (symptom vs diagnosis based) may affect findings. Depressive disorder is characterized by an increase of pro-inflammatory bacteria, while anti-inflammatory butyrate-producing genera are depleted.

Analysis of factors influencing substance use craving among Chinese substance users.

Background: Substance use has been a serious public safety issue. It not only affects the users' physical and mental health but is also detrimental to social stability. To improve our understanding of this issue, the present study looked to examine the factors influencing substance use craving and develop interventions to reduce craving and relapse among substance users. Materials and methods: A total of 502 substance users were included in this study. Socio-demographic characteristics and substance use-related characteristics were recorded using self-developed forms. With regard to psychological traits, we used the self-esteem scale, the experience of shame scale, and the revised Cheek and Buss shyness scale to assess the self-esteem, shame, and shyness of substance users, respectively. The degree of substance use craving of substance users was assessed using the visual analog scale (VAS). Data were analyzed using independent samples T-test, Pearson correlation analysis, and multiple linear regression analysis, as appropriate. Results: The majority of the substance users were unmarried, employed, and with lower education levels. For substance use-related characteristics, the age of first use was 27.52 ± 8.30 years and the duration of substance use was 12.29 ± 7.72 years. The scores of their self-esteem, shame, and shyness were 25.65 ± 3.19, 57.26 ± 7.82, and 37.8 ± 7.13, respectively. All substance users rated the intensity of their substance use cravings using the VAS, which showed that the mean score was 2.83 ± 1.87. Multiple linear regression analysis showed that substance use craving was positively associated with the frequency of substance use (ß = 0.186, P < 0.001), times of substance rehabilitation (ß = 0.128, P = 0.003), shyness (ß = 0.211, P < 0.001), and shame (ß = 0.091, P = 0.033), and negatively associated with self-esteem (ß = -0.117, P = 0.008). Conclusion: Factors and psychological traits related to substance use are important to account for substance use craving and relapse. Thus, our findings are helpful for a better understanding of the extent of substance use cravings among users and the selection of appropriate interventions to control the craving and relapse.

Characteristics and Mediating Effect of Gut Microbiota With Experience of Childhood Maltreatment in Major Depressive Disorder.

Gut microbiota and childhood maltreatment are closely related to depressive symptoms. This study aimed to analyze the characteristics of gut microbiota in major depressive disorder (MDD) patients with childhood maltreatment experience and explore the correlation between gut microbiota, childhood maltreatment, and depressive symptoms. A total of 37 healthy controls (HCs) and 53 patients with MDD were enrolled, including 18 MDD patients without childhood maltreatment experience and 35 MDD patients with childhood maltreatment experience. The Hamilton's Depression Scale (HAMD-24) and Childhood Trauma Questionnaire-Short Form (CTQ-SF) were used to evaluate their depressive symptoms and childhood maltreatment experience, respectively. The composition of gut microbiota was evaluated using 16S rRNA sequencing. Spearman's correlation analysis was used to evaluate the correlation between different gut microbiota, depressive symptoms and childhood maltreatment. The mediation analysis was used to evaluate the mediating effect of gut microbiota. In the α-diversity analysis, we found that the Simpson index and Pielou's Evenness index differed significantly between MDD patients without childhood maltreatment experience and HCs. In the ß-diversity analysis, principal coordinate analysis (PCoA) showed significant differences between MDD patients without childhood maltreatment experience, MDD patients with childhood maltreatment experience and HCs. Twenty-seven different bacteria were identified through Linear discriminant analysis effect size (LEfSe) analysis at different levels of classification. The analysis of the correlation showed that Blautia, Bifidobacterium, Bacteroides, Roseburia, and Phascolarctobacterium were significantly correlated with HAMD and CTQ-SF scores. The mediation analysis showed that childhood maltreatment had a significant direct effect on the patients' depressive symptoms, and Blautia, Bifidobacterium, Roseburia had a significant mediating effect. The findings of this study suggested that MDD patients with childhood maltreatment experience had different gut microbiota, which might have a mediating effect on the influence of childhood maltreatment on depressive symptoms.

The association of childhood adversities and mental health problems with dual-harm in individuals with serious aggressive behaviors.

BACKGROUND: The coexistence of self-harm and aggression, which is referred to as dual-harm, is commonly seen in forensic population. Self-harm and aggression have often been studied separately, previous studies on risk factors of aggression or self-harm mainly focused on childhood adversities, emotional regulation, impulsivity and psychopathology, given their importance in the two behaviors. However, the factors associated with dual-harm remain unclear. This study aimed to explore potential risk factors associated with co-occurring self-harm among individuals with serious aggressive behaviors. METHODS: This multi-center, cross-sectional case-control study was conducted from May 2013 to January 2016 and involved seven qualified forensic institutes located in seven provinces in China. Participants were individuals with serious aggressive behaviors and were suspected to have mental disorders. Lifetime history of self-harm was obtained by a self-report questionnaire, and serious aggressive behaviors were assessed with the use of participants' forensic archive. Sociodemographic and clinical information were collected using a self-designed standardized data collection form, and childhood adversities was assessed using a clinician-rated scale designed by our research team. The Psychopathy Checklist-Revised (PCL-R) was used to assess psychopathic traits and the Brief Psychiatric Rating Scale (BPRS) was used to assess psychiatric symptoms of the participants. Univariate and multivariate logistic regression analyses were performed to analyze the relevant factors for dual-harm. RESULTS: A total of 423 individuals with serious aggressive behaviors were enrolled in the current study. Of them, 74 (17.5%) with self-harm history assigned into the dual-harm group (D-H) and 349 (82.5%) without self-harm history assigned into the aggression-only group (A-O). According to the binary logistic regression analysis, current diagnosis of mood disorder (OR = 3.2, 95%CI: 1.2-8.5), child abuse (OR = 2.8, 95%CI: 1.3-6.2), parental death (OR = 3.0, 95%CI: 1.2-7.5), and the score of the affective subscale in BPRS (OR = 1.7, 95%CI: 1.3-2.4) were significantly associated with dual-harm. CONCLUSIONS: Our study suggested the necessity of integrated evaluation of self-harm among individuals with serious aggressive behaviors. Childhood adversities and psychiatric symptoms in this population require special attention.

Abnormal gut microbiota and bile acids in patients with first-episode major depressive disorder and correlation analysis.

AIM: Gut microbiota and its metabolite bile acids may play a significant role in the occurrence and development of major depressive disorder (MDD). Therefore, this study analyzes gut microbiota and bile acids, as well as their correlation in patients. METHODS: Thirty-one patients with MDD and 29 healthy controls (HCs) were enrolled in this study. We collected their both blood and feces. Plasma bile acid content was determined by liquid chromatography-mass spectrometry and gut microbiota was detected by 16SrRNA gene sequencing and subsequently analyzed. We also analyzed the correlation between different gut microbiota, bile acids, and Hamilton Depression (HAMD) score. RESULTS: The α-diversity analysis found that Simpson and Pielou evenness index was much higher in HCs than in the patients with MDD. The ß-diversity of the two groups were differences by nonmetric multidimensional scaling analysis. Linear discriminant analysis effect size analysis identified 16 different strains. Bile acids detection showed that 23-nordeoxycholic acid in patients with MDD was significantly higher than in HCs, whereas taurolithocholic acid (TLCA), glycolithocholic acid (GLCA), and lithocholic acid 3-sulfate were significantly lower. Spearman correlation analysis showed that Turicibacteraceae, Turicibacterales, and Turicibacter were positively related with TLCA, GLCA, glycodeoxycholic acid (GDCA), and taurodeoxycholic acid, and were negatively correlated with HAMD score. At the same time, TLCA, GLCA, and GDCA were negatively correlated with HAMD score. CONCLUSIONS: Gut microbiota and bile acids metabolism are disturbances in MDD, and there exists a correlation between gut microbiota and bile acids metabolism. Moreover, their interaction may be related to the pathophysiological mechanism of MDD.

Sociodemographic, occupational, and personal factors associated with sleep quality among Chinese medical staff: A web-based cross-sectional study.

Background: Sleep quality among medical staff affects not only their own health but also the health of their patients. This study aimed to investigate the sociodemographic, occupational, and personal factors associated with sleep quality among medical staff in mainland China. Methods: An online survey was conducted from January 10 to February 5, 2019, involving 3,684 medical staff (female: 84.9%; mean age: 31.6 ± 7.7; age range: 18-72). Sleep quality was measured by the Chinese version of the Pittsburgh Sleep Quality Index (C-PSQI). Sociodemographic, occupational characteristics, and personal lifestyle factors were measured by standard questions. Binary logistic regression analyses were used to determine the factors associated with sleep quality. Results: 57.9% (95% CI: 56.3-59.5%) of the study population experienced poor sleep quality (C-PSQI > 5). Binary logistic regression showed that poor sleep quality were associated with lower level of education, higher level of hospital care, longer weekly working hours, more than 30 min of cell phone use at bedtime, shift work (OR 1.33, 95% CI[1.12-1.58], P = 0.001), lack of regular naps (OR 1.46, 95% CI[1.26-1.69], P < 0.001) and lack of routine exercise (OR 1.69, 95% CI[1.46-1.97], P < 0.001). Conclusions: Poor sleep quality is highly prevalent among medical staff in mainland China. The findings indicate that appropriate strategies, such as implementing regular breaks, regulating overtime work and vacation interruptions, as well as developing exercise programs, relaxation training, and stress-management programs could help improve the sleep quality of medical staff.

The influence of stagnant and transport types weather on heavy pollution in the Yangtze-Huaihe valley, China.

The ambient atmospheric PM2.5 concentrations in Anhui Province, China, which links the Yangtze River Delta region, China's fastest growing economy area, with the Beijing-Tianjin-Hebei (BTH) region, China's most polluted region, are influenced not only by local emissions, but also by changes in regional circulation. During the period 2013-2017, when China adopted a series of pollution abatement measures, there were still occasional pollution episodes with significant increases in PM2.5 concentrations. PM2.5 rise instead during the period 2013-2017 in Anhui (the Center of the Yangtze-Huaihe, YH), when pollution emissions continued to decrease? What is the controlling mechanism behind these? By analyzing elements such as ground-based PM2.5 concentration and the planetary boundary layer (PBL) structure affecting it as well as larger scale circulation, combined with the analysis of a parameterized index, one can find that aerosol pollution in the YH region can usually be classified into three types. (1) There is a short-term transport stage (TS) in the initial stage of pollution, then as the pollutant concentrations increase, the PBL height decreases, the temperature inversion is gradually formed or strengthened, the wind speed decreases and the relative humidity of the lower layer increases, forming a two-way feedback mechanism in the cumulative stage (CS). (2) Pollutant concentrations will not drop rapidly in the later stage of CS, while a short-term TS will occur again. (3) The explosive rise (ER) events are mainly affected by transportation in the YH. The first of these types tends to be accompanied by the emergence and maintenance of heavy pollution periods (HPEs), and some phases is accompanied by explosive rises (ERs) in PM2.5 that at least double in a short period of time. To sum up, deterioration of meteorological conditions explaining approximately 68% to the increase in PM2.5 in the ER.

Injuries in Left Corticospinal Tracts, Forceps Major, and Left Superior Longitudinal Fasciculus (Temporal) as the Quality Indicators for Major Depressive Disorder.

At present, the etiology and pathogenesis of major depressive disorder (MDD) are still not clear. Studies have found that the risk of first-degree relatives of MDD is 2-3 times that of the general population. Diffusion tensor imaging (DTI) has been previously used to explore the pathogenesis of MDD. The purpose of this study is to explore the etiology of MDD by DTI and further to explore the correlation between its clinical characteristics and the structural changes of white matter in the brain. The study included 27 first-episode, drug-naive patients with MDD, 16 first-degree relatives without MDD, and 28 healthy control subjects with no family history of MDD (HC). Results showed that the fractional anisotropy (FA) differences among the three groups were mainly in the left anterior thalamic radiation (LATR), right anterior thalamic radiation (RATR), left corticospinal tracts (LCST), forceps major (FMa), right inferior longitudinal fasciculus (RILF), and left superior longitudinal fasciculus (temporal) (LSLF(T)). Among the 6 sites, LCST, FMa, and LSLF(T) showed significant differences between MDD and First-degree relatives compared to HC. MDD patients had significant emotional symptoms, somatic symptoms, and cognitive impairment. FMa FA was significantly positively correlated with delayed memory score (r = 0.43, P = 0.031), and RILF FA was significantly negatively correlated with the FSS score (r = -0.42, P = 0.028). These results revealed that the white matter characteristics of MDD-susceptible patients were LCST, FMa, and LSLF(T) lesions, all of which may be quality indicators of MDD.

Association of the TLR4 gene with depressive symptoms and antidepressant efficacy in major depressive disorder.

At present, the etiology and pathogenesis of major depressive disorder(MDD) are still unclear. Some studies have shown that toll-like receptor 4 may play an important role in MDD. However, little is currently known about the association between TLR4 single gene polymorphisms (SNPs) and depressive symptoms and antidepressant efficacy.The aim of this study is to analyze whether TLR4 SNPs are associated with depressive symptoms and antidepressant efficacy. The study consisted of 438 patients with first-episode depression. We analyzed three TLR4 SNPs (rs1927911, rs11536889, and rs7873784) and obtained the baseline and 6-week scores using the 17-item Hamilton Depression Rating Scale (HAMD17) and its five-factor model. Allelic and genotypic association tests between TLR4 SNPs and HAMD17 total and cluster scores were performed with UNPHASED, while chi-square tests to analyze the association between TLR4 SNPs and response to antidepressants were performed with SPSS. Patients with the rs1927911-GG genotype exhibited higher scores of anxiety (physical symptoms) and anxiety (somatic). Patients with rs1927911-G also exhibited higher anxiety (physical symptoms) and anxiety (somatic) scores. Patients with rs11536889-GG had significantly lower suicide scores and higher psychomotor retardation scores. Patients with rs11536889-G also had significantly lower suicide scores and higher psychomotor retardation scores. Patients with rs7873784-G had higher anxiety (physical symptoms) and anxiety (psychological) scores. There was no significant difference between antidepressant efficacy and TLR4 gene polymorphisms. These findings provide evidence that TLR4 plays an important role in anxiety, suicide, and other symptoms in patients with MDD. No relationship was found between TLR4 gene polymorphisms and antidepressant efficacy in this study. Further research is needed on gene polymorphisms and the expression of TLR4 in patients with MDD.

The two-way feedback effect between aerosol pollution and planetary boundary layer structure on the explosive rise of PM2.5 after the "Ten Statements of Atmosphere" in Beijing.

Are there still persistent heavy aerosol pollution episodes (HPEs) in Beijing one year after the implementation of the "Action Plan for the Prevention and Control of Air Pollution ("Ten Statements of Atmosphere" in China: 2013-2017)"? Will the cumulative aerosol pollution still induce significant two-way feedback between PM2.5 and the planetary boundary layer structure? Answers to these matters are particular concerns of the government and the public. The analysis of the vertical structure of the aerosol and meteorological factors in planetary boundary layer shows that the two-way feedback between unfavorable meteorological conditions and PM2.5 pollution cumulating is still the primary mechanism for the maintenance of HPEs, accounting especially ~66% to 88% for explosive rise in PM2.5, in autumn and winter in Beijing area a year after the "Ten Statements of Atmosphere". This effect also shows that the concentration of PM2.5 in Beijing had not fallen low enough to decouple the influence of unfavorable meteorological factors. The increased level of PM2.5 mass during the explosive rise stage was similar to those of the precursor gases of NO2, SO2 and CO, as well as to the declining ratio of the boundary layer height (BLH), which also suggest that the interaction between PM2.5 cumulating and the boundary layer structure is playing a leading role for the maintenance of HPEs and the PM2.5 explosive rise in Beijing. The depolarization ratio signal of the Lidar also shows that the transit of mineral aerosols from the northwest over Beijing often appears in the upper layer of the planetary boundary layer or higher atmosphere during the late or subside stage of HPEs.

Seasonal variation of atmospheric vertical extinction and its interaction with meteorological factors in the Yangtze River Delta region.

Based on ground-based lidar and microwave radiometer observations in Hangzhou from 1 January 2013 to 31 December 2015, the monthly characteristics of diurnal extinction as well as atmospheric boundary layer (ABL) were studied. The interactions between temperature (T), humidity fields including relative humidity (RH) and specific humidity (SH) and atmospheric stratification (AS) were analyzed to discuss the meteorological factors in the Yangtze River Delta region during the study period. The top of ABLMPL varied from 0.8 km to 1.0 km throughout in January with higher extinction intensity close to the surface combined to the largest PM2.5 about 100-120 µg/m3. Then the ABLMPL could develop up to 1.5 km in the spring due to the weaker extinction during the daytime. The RH in the whole column in January and December was lower than the mean value (ranging from 5% to 20%) distributed from the ground to 3 km. From May to September, the RH anomaly profiles became positive contributed to larger extinction by strengthened the particle scattering ability. In January and December, the AS was stable from the surface to 3 km coincided with the extinction distribution; while in July and August, the gradient of Δθse decreased which favored the diffusion of particle in the air. Moreover, April and October presented turning points in the variation of θse. The humidity field reveals a stable condition in January and December which favored particles suppressed from the near surface to 3 km; the temperature field has tended towards a neutral state in most months except for February. The first change-point of the meteorological fields was found in April possibly attributable to the abnormal abrupt in the subtropical high. This study could have important reference for understanding regional air quality and governing air control.

Specific Gray Matter Volume Changes of the Brain in Unipolar and Bipolar Depression.

To identify the common and specific structural basis of bipolar depression (BD) and unipolar depression (UD) is crucial for clinical diagnosis. In this study, a total of 85 participants, including 22 BD patients, 36 UD patients, and 27 healthy controls, were enrolled. A voxel-based morphology method was used to identify the common and specific changes of the gray matter volume (GMV) to determine the structural basis. Significant differences in GMV were found among the three groups. Compared with healthy controls, UD patients showed decreased GMV in the orbital part of the left inferior frontal gyrus, whereas BD patients showed decreased GMV in the orbital part of the left middle frontal gyrus. Compared with BD, UD patients have increased GMV in the left supramarginal gyrus and middle temporal gyrus. Our results revealed different structural changes in UD and BD patients suggesting BD and UD have different neurophysiological underpinnings. Our study contributes toward the biological determination of morphometric changes, which could help to discriminate between UD and BD.

Global view on China's foggy-haze associated with air-pollutant conveyor belts.

Upper air and surface data from 1960 to 2016, NCEP reanalysis from 1990 to 2016, air composition data from 2015 to 2016, and data from the drift automatic weather station in the Arctic from August 2012 to February 2013 are used to analyze the heavy foggy haze in China from a global perspective. Our findings show that sensitive foggy haze in winter is located in the eastern region of China because of the comprehensive effect of multi-factor meteorological conditions and the response to climate change under global warming as follows. (1) For the past half-century, two winter monsoon airflows blow from the East Asian continent and adjacent sea to North China. The airflow in the intermediate zone (North China) between the two winter monsoon airflows generates a retained circulation owing to the Earth's rotation because wind velocities over land and sea are different and their wind intensities are weakened. The circulation retention index has been on the rise in recent years, causing a "static stability" that retains or stabilizes air masses over this area. (2) Under global warming, polar ice has shrunk to a historical lowest over the years. The melting polar ice results in explosive heating and humidification in the lower troposphere leading to increased aerosol concentrations, which is conducive to maintaining or strengthening the Arctic haze. (3) The two winter monsoon pathways run over the Eurasian continent and the surface of the adjacent Sea of Okhotsk, thus affecting North China. These results are consistent with the airflow of the pollutant conveyor belt channeling from the Arctic haze zone. As a result, the pollutant conveyor belt from the Arctic haze zone as well as the pollutant conveyor belts from West Asia and North Africa contribute substantially to the high frequency of winter foggy haze over eastern China.

The effects of the "two-way feedback mechanism" on the maintenance of persistent heavy aerosol pollution over areas with relatively light aerosol pollution in northwest China.

Persistent heavy aerosol pollution episodes (HPEs) often occur in the central and eastern regions of China during the wintertime. When PM2.5 mass concentration cumulates to a certain extent that normally exceeds 100 µg m-3, the PM2.5 pollution will then further worsen the meteorological conditions in boundary layer (BL), resulting in significant two-way feedback between the cumulative PM2.5 pollution and worsened meteorological conditions. In the less polluted northwest area of China, whether there is significant two-way feedback phenomenon mentioned above after the accumulation of PM2.5 mass concentration has always been an issue of concern for understanding the full picture of meteorological causes of HPEs in China. Here, measurements of PM2.5 concentration, meteorological data and an integrated pollution-linked meteorological index (PLAM) are used to characterize the relationship between meteorological elements and PM2.5 concentration in persistent HPEs from 1 December 2016 to 10 January 2017 in Lanzhou and Urumqi. In early stage of the HPEs formation, the general 500 hPa circulation situations are normally high-pressure ridge or zonal westerly airflow patterns, associating with worsened meteorological conditions. At this time, with the decrease of BL height, the mass concentration of PM2.5 also increases as the pollutants mix in a relatively small space as compared to the clean period. When PM2.5 cumulates to a certain extent (above 75 µg m-3 in Lanzhou and above 100 µg m-3 in Urumqi), there are often obvious inversion and humidification in the near-surface. The inversion is mainly caused by the accumulation of the PM2.5 concentration, which indicates that even in northwest China, where anthropogenic activities are less affected and PM2.5 pollution is less serious, the cumulative PM2.5 can nonetheless worsen meteorological conditions. The worsened meteorological conditions, which are quantified by the PLAM index, dominate the changes in PM2.5 in the explosive growth of persistent HPEs (accounted for 50-85%).

Influence of meteorological conditions on explosive increase in O3 concentration in troposphere.

Ozone (O3) pollution in the troposphere, especially at the surface layer, has become a focus of attention in recent years. High O3 concentration events tend to occur frequently in north China, Yangtze, the Pearl River Delta, and the Sichuan Basin, among others. Studies on the meteorological contribution to O3 in the troposphere have become a new direction for the scientific community. This research intends to explore how meteorological conditions contribute to O3 pollution in all seasons on the basis of further studies of the PLAM index. Our findings are as follows. (1) In pollution-sensitive areas, following a height uplift in the pollution mixing layer (H_PML), NO2 concentration decreases initially, followed by an explosive increase (EI) in O3 concentration after sunrise. (2) This process varies significantly by season and area. (3) According to an analysis of the meteorological conditions causing rises in O3 concentration within a few hours after sunrise, the initial decrease-subsequent increase in NO2 versus O3 concentration satisfies the law of exponent power rule, according to which seasonal and regional differences in coastal and inland areas depend on coefficients α and ß. The explosive increase in O3 concentration, decrease in NO2 concentration, and characteristics of their diurnal cycles are also discussed. (4) Under the meteorological condition of static stability, below the static and stable cover, the H_PML of the polluted mixed layer consistently indicates the reciprocating cycle of day uplift and night pressure. The effect of air pump suction on the pollutant is an important mechanism of large-scale pollution in the study area under the condition of static and stable cover. (5) The influencing mechanism of meteorological conditions in the diurnal H_PML cycle aids in improving the understanding of O3 concentration increases in the troposphere.

Interdecadal changes of summer aerosol pollution in the Yangtze River Basin of China, the relative influence of meteorological conditions and the relation to climate change.

Winter is a season of much concern for aerosol pollution in China, but less concern for pollution in the summertime. There are even less concern and larger uncertainty about interdecadal changes in summer aerosol pollution, relative influence of meteorological conditions, and their links to climate change. Here we try to reveal the relation among interdecadal changes in summer's most important circulation system affecting China (East Asian Summer Monsoon-EASM), an index of meteorological conditions (called PLAM, Parameter Linking Air Quality and Meteorological Elements, which is almost linearly related with aerosol pollution), and aerosol optical depth (AOD) in the middle and lower reaches of the Yangtze River (M-LYR) in central eastern China during summertime since the 1960's. During the weak monsoon years, the aerosol pollution load was heavier in the M-LYR and opposite in the strong monsoon years mainly influenced by EASM and associated maintenance position of the anti-Hadley cell around 115°E. The interdecadal changes in meteorological conditions and their associated aerosol pollution in the context of such climate change have experienced four periods since the 1960's, which were a relatively large decreased period from 1961 to 1980, a large rise between 1980 and 1999, a period of slow rise or maintenance from 1999 to 2006, and a relatively rapid rise between 2006 and 2014. Among later three pollution increased periods, about 51%, 25% and 60% of the aerosol pollution change respectively come from the contribution of worsening weather conditions, which are found to be greatly affected by changes in EASM.

Impact of air pollution control measures and weather conditions on asthma during the 2008 Summer Olympic Games in Beijing.

The alternative transportation strategy implemented during the 2008 Summer Olympic Games in Beijing provided an opportunity to study the impact of the control measures and weather conditions on air quality and asthma morbidity. An ecological study compared the 41 days of the Olympic Games (8 August-17 September 2008) to a baseline period (1-30 June). Also, in order to emphasize the impact of weather conditions on air quality, a pollution linking meteorological index (Plam) was introduced to represent the air pollution meteorological condition. Our study showed that the average number of outpatient visits for asthma was 12.5 per day at baseline and 7.3 per day during the Olympics-a 41.6% overall decrease. Compared with the baseline, the Games were associated with a significant reduction in asthma visits (RR 0.58, 95%CI: 0.52-0.65). At 16.5 visits per day, asthma visits were also significantly higher, during the pre-Olympic period (RR 1.32, 95% CI: 1.15-1.52). The study also showed that the RR of asthma events on a given day, as well as the average daily peak ozone concentration during the preceding 48-72 h, increased at cumulative ozone concentrations of 70 to 100 ppb and 100 ppb or more compared with ozone concentrations of less than 70 ppb (P < 0.05). We concluded that along with "good" weather conditions, efforts to reduce traffic congestion in Beijing during the Olympic Games were associated with a prolonged reduction in air pollution and significantly lower rates of adult asthma events. These data provide support for efforts to reduce air pollution and improve health via reductions in motor vehicle traffic.