City In Southwest China Research Articles

Impact of COVID-19 restrictions liberalization on air quality: a case study of Chongqing, Southwest China.

To mitigate the societal impact of the COVID-19 pandemic, China implemented long-term restrictive measures. The sudden liberalization at the end of 2022 disrupted residents' daily routines, making it scientifically intriguing to explore its effect on air quality. Taking Chongqing City in Southwest China as an example, we examined the impact of restriction liberalization on air quality, identified potential sources of pollutants, simulated the effects of abrupt anthropogenic control relaxation using a Random Forest Model, and applied an optimized model to predict the post-liberalization pollutant concentrations. The results showed increases in PM2.5 (72.3%), PM10 (67.7%), and NO2 (21.9%) concentrations, while O3 concentration decreased by 20.5%. Although potential pollution source areas contracted, pollution levels intensified with northeastern Sichuan, interior Chongqing, and northern Guizhou being major contributors to pollutant emissions. Anthropogenic emissions accounted for 26.7 ~ 33% changes in PM2.5 and PM10 concentrations while meteorological conditions contributed to 40.2 ~ 43.3% variations observed during the period. The optimized model demonstrated a correlation between predicted and observed values with R2 ranging from 0.70 to 0.89, enabling accurate prediction of post-liberalization pollutant concentrations. This study can enhance our understanding regarding the impact of sudden social lockdown relaxation events on air quality while providing support for urban air pollution prevention.

Co-tracing of groundwater emerging and conventional contaminants in karst area of Southwest China: Distribution, source, and source-specific health risks

Groundwater pollution, especially the co-contamination of emerging contaminants (ECs) and conventional contaminants, is increasingly recognized as a critical global concern. Karst aquifers are found throughout the world, providing critical water sources and sustaining rivers and ecosystems, and are particularly vulnerable to pollution. In this study, the characteristics of the contamination, potential sources, and source-specific health risks related to ECs and trace elements (TEs) in groundwater were investigated in Guiyang (a typical karst city in southwest China). The distribution of TEs followed a descending pattern from urban to suburban to rural areas. Interestingly, the median concentrations (217 ng/L) of Caffeine (CAF) in rural areas surpassed those in urban areas (145 ng/L) and even exceeded these in densely populated areas. Additionally, ECs and TEs in groundwater are significantly influenced by population density and land use types within a 1000-meter buffer zone around the sampling sites. Hierarchical cluster analysis and positive matrix factorization suggested that five principal sources of contamination were identified: domestic wastewater (29.7 %), industrial production (25.2 %), agricultural activities (16.3 %), natural and industrial sources (14.9 %), and pharmaceuticals (13.9 %). Monte Carlo simulations revealed that the non-carcinogenic risks to children in urban areas are significant, with 30.0 % of these risks exceeding the safety threshold. Source-specific health risk assessments indicated that industrial production is the primary source of risk. Furthermore, this study introduces a co-tracing method to trace the sources of groundwater contamination in karst systems. The co-tracing method based on the ECs and TEs allows for a deeper understanding of contaminant transfer and its fate in karst groundwater.

Temporal and spatial characteristics of carbon storage and its response to land-use change in Chengdu, China

The accurate monitoring of the dynamic relationship between land use and carbon storage can provide a scientific basis for the government to formulate carbon emission reduction policies and promote the green development of cities, achieving a win–win situation for both ecology and the economy. As a national central city in southwest China, Chengdu has experienced rapid land-use changes in the past decade due to the implementation of development strategies such as urban-rural integration and the construction of a “Park City.” To explore the spatial and temporal distribution characteristics of carbon storage in Chengdu during this period, three representative years (2010, 2015, and 2020) were selected to estimate the changes in carbon storage using the Integrated Valuation of Ecosystem Services and Trade-offs (InVEST) model. From 2010 to 2020, the land-use changes in Chengdu primarily manifested in the mutual transformation between cultivated land, forest land, and construction land. The conversion between the high-carbon-density-land-use type and the low-carbon-density-land-use type was an important driving factor for the change in carbon storage in Chengdu, and it was also the main reason for the overall reduction of carbon storage in the city. The carbon source areas of Chengdu demonstrated an aggregated spatial pattern, with the northern and southern parts of the city being the main carbon source areas. In contrast, the carbon sink areas were mainly distributed in the western and eastern parts, as well as the ecological park around the expressway in Chengdu. This distribution was mainly due to increased efforts to restore inefficiently used cultivated land back to forest and grassland. The proposal of the “Park City” strategy has promoted the construction of green infrastructure in Chengdu and has effectively increased urban carbon sinks.

Vaccination intentions of hypertensive Chinese individuals during the COVID-19 epidemic: a structural equation modeling study

ObjectiveGiven the high prevalence of hypertension among Chinese adults, this population is at a significantly increased risk of severe COVID-19 complications. The purpose of this study is to assess the willingness of Chinese hypertensive adults to receive the COVID-19 vaccine and to identify the diverse factors that shape their vaccination decisions.MethodsSampling was conducted utilizing multistage stratified random sampling, and ultimately, a total of 886 adult hypertensive patients from Luzhou City in Southwest China were included in this study. The questionnaire design was based on the Theory of Planned Behaviour and was used to investigate their willingness to be vaccinated with COVID-19. Structural equation modeling was employed for data analysis.ResultsThe results showed that 75.6% of hypertensive individuals were willing to receive COVID-19 vaccination. The structural equation modeling revealed that Subjective Norms (path coefficient = 0.361, CR = 8.049, P < 0.001) and Attitudes (path coefficient = 0.253, CR = 4.447, P < 0.001) had positive effects on vaccination willingness, while Perceived Behavioral Control (path coefficient=-0.004, CR=-0.127, P = 0.899) had no significant impact on Behavioral Attitudes. Mediation analysis indicated that Knowledge (indirect path coefficient = 0.032, LLCI = 0.014, ULCI = 0.058), Risk Perception (indirect path coefficient = 0.077, LLCI = 0.038, ULCI = 0.124), and Subjective Norms (indirect path coefficient = 0.044, LLCI = 0.019, ULCI = 0.087) significantly influenced vaccination willingness through Attitudes as a mediating factor.ConclusionThe willingness of hypertensive individuals to receive the COVID-19 vaccination is not satisfactory. The Theory of Planned Behavior provides valuable insights into understanding their vaccination intentions. Efforts should be concentrated on enhancing the subjective norms, attitudes, and knowledge about vaccination of hypertensive patients.

Exploring new discoveries of steel fining in a Western Han Dynasty city in southwest China: A case study of steel fining remains excavated from the ancient Xindu city in Sichuan Province

AbstractArchaeological discoveries and historical documents show that the Chengdu Plain was the most important iron production center in the southwest region of China during the Qin and Han dynasties. However, due to the lack of archaeological evidence, the iron production technology of cities in the Chengdu Plain during the Qin and Han dynasties remains unclear. The Xindu city site is located in Qingbaijiang District, Chengdu Sichuan Province. It was an important city site in the Chengdu Plain during the Han and Jin dynasties. During excavation of the Xindu city site, archaeologists unearthed a large number of metallurgical remains such as slags and tuyeres, as well as two severely damaged hearth bases near the western city wall. Scientific analysis results suggest that the metallurgical remains are related to the steel fining process and could be dated back to the Western Han Dynasty. The metallurgical remains in the Xindu city are the earliest known artifacts associated with the steel fining process in southwest China. This discovery also marks the first identification of iron industry workshops in a Han Dynasty city in the Chengdu Plain. The findings reveal a different industrial layout pattern from previously discovered Han Dynasty metallurgical sites in the Chengdu Plain. Additionally, this discovery provides archaeometallurgical evidence for the central government's development in southwest China during the Han Dynasty.

Towards inclusive urbanism: An examination of urban environment strategies for enhancing social equity in Chengdu's housing zones

With rapid urbanization, the urban heat island (UHI) effect has become a major problem worldwide. This study focuses on the relationship between Urban Green Space (UGS) and Land Surface Temperature (LST), providing insights into how natural environment, urban construction, and human activities influence this relationship by analyzing housing areas of different tiers. Utilizing the LightGBM machine learning approach, this study takes Chengdu City in Southwest China as a research area and finds that green space has a more significant cooling effect on LST in the middle-market housing and affordable housing areas. Furthermore, within the NDVI range of 0.37 to 0.48, the LST decreases by 0.63℃ for every 0.1 increase. Additionally, the study reveals that urban construction characteristics, such as building density and building height, exert a more significant influence on LST in middle-market housing and affordable housing areas, with a contribution rate of 23.61 % observed in middle-market housing areas and the lowest contribution rate of 17.84 % observed in high-end housing areas. Overall, our research emphasizes the importance of addressing urban thermal disparities, particularly in diverse housing areas, by prioritizing green space augmentation and optimizing built environments, thereby offering actionable insights for equitable and sustainable urban planning.

Evaluation and associated factors of public health emergency management among medical college students in a city in Southwest China: a cross-sectional study

BackgroundColleges and universities face an increased risk of public health emergencies. Among them, medical colleges and universities deserve more attention as they serve as the play a fundamental role in providing public health emergency services and in cultivating medical professionals. Effectively managing infectious disease prevention and control, as well as responding to public health emergencies in medical colleges and universities, is of great importance for enhancing the capacity of social emergency governance and improving the completeness of the public health system. This study aims to understand the management of public health emergencies in medical colleges in a city in southwest China, explore the factors associated with medical college students’ evaluations, and provide recommendations for emergency management mechanisms in colleges and universities.MethodsIn total, 781 medical college students were selected through stratified random sampling and surveyed using a questionnaire. The main factors affecting students’ evaluation of emergency management were analyzed using multiple linear regression and structural equation modeling.ResultsThe overall emergency management situation in medical colleges was relatively complete, with satisfactory results. Medical college students’ satisfaction with the timeliness of prevention measures was the highest, while the publicity and education were the lowest. Multiple linear regression analysis showed that grades, emergency education, -simulation training, -information reporting, and dynamic adjustment measures were associated with the evaluation of emergency management by medical students.ConclusionsAlthough the evaluation of emergency management in medical colleges was generally positive, certain limitations still existed. To improve the development of the public health system, colleges and universities should constantly reform and innovate emergency management mechanisms according to the important links in the prevention and control processes.

Predicting the Distributions of Morus notabilis C. K. Schneid under Climate Change in China

As one of the common mulberry tree species, Morus notabilis C. K. Schneid plays a significant role in various industries such as silkworm rearing, papermaking, and medicine due to its valuable mulberry leaves, fruits, and wood. This study utilizes the maximum entropy (MaxEnt) model to predict the potential distribution of M. notabilis in China under future environmental changes. By integrating the relative percentage contribution score of environmental factors with jackknife test analysis, important variables influencing the distribution of M. notabilis were identified along with their optimal values. The results indicate that Annual Precipitation (bio12), Precipitation of Driest Month (bio14), Min Temperature of Coldest Month (bio6), Temperature Annual Range (bio5–bio6) (bio7), Precipitation of Warmest Quarter (bio18), and Precipitation of Coldest Quarter (bio19) are the primary environmental variables affecting its potential distribution. Currently, M. notabilis exhibits high suitability over an area spanning 11,568 km2, while medium suitability covers 34,244 km2. Both current and future suitable areas for M. notabilis are predominantly concentrated in Sichuan, Yunnan, and Guizhou provinces, as well as Chongqing city in southwest China. Under the SSP5-8.5 scenario representing high greenhouse gas concentrations by 2050s and 2090s, there is an increase in high suitability area by 2952 km2 and 3440 km2, with growth rates reaching 25.52% and 29.74%, respectively. Notably, these two scenarios exhibit substantial expansion in suitable habitats for this species compared to others analyzed within this study period.

An Assessment of the Safety Effects of Roadside Barriers on Reducing Mountainous Crash Injury Severity

Roadside barriers have proven effective in preventing run-off-road accidents that occurred in mountainous areas. Nonetheless, the influence of variables impacting the severity of injuries resulting from collisions involving distinct types of roadside barriers may diverge. This study delves into the factors that influence the severity of driver’s injuries in crashes encompassing three specific varieties of roadside barriers in mountainous regions, namely, W-beam barriers, flexible barriers, and roadside trees. The evolution of these factors over time is examined through the application of a random parameters logit modeling approach with heterogeneity in means and variances (RPLHMVs). By employing injury-severity data from 2016 to 2019 for the mountainous regions of a city in Southwest China, various potential influencing factors encompassing driver-, vehicle-, road-, and environment-specific characteristics are subjected to statistical analysis. The extent of the impact of identified statistically significant factors on driver’s injury severity is assessed through the computation of pseudoelasticities. The findings reveal distinctions in the outcomes of driver’s injury severity contingent upon the type of roadside barrier encountered during vehicle impacts. To illustrate, collisions involving W-beam barriers are more prone to result in severe injuries. Moreover, the influence of variables determining driver’s injury severity displays noteworthy temporal shifts. Notably, the pseudoelasticities of numerous explanatory variables remain temporally consistent for incidents involving flexible or roadside barriers. In contrast, crashes involving W-beam barriers highlight that solely the speeding indicator demonstrates temporally stable pseudoelasticities. The insights garnered from this investigation offer the potential to contribute to the formulation of fresh guidelines for the design and selection of roadside barriers aimed at mitigating the severity of injuries incurred in crashes within mountainous regions.

Equity of health resource allocation in Chongqing, China, in 2021: a cross-sectional study

BackgroundChongqing, the most populous city in Southwest China. This study aims to examine the equity of health resource allocation in Chongqing using the latest statistics, analyse possible shortcomings and propose...

Development laws of geological hazards along urban highway in Southwest China and countermeasures for prevention and control

China is a mountainous country with highly developed road geologic hazards, which pose a great threat to the construction and operation of highways, bridges, and tunnels and to the safety of people and property. This paper discussed the types, basic features, formation, and prevention conditions of road geologic hazards in China based on field research and study data collected thus far. The study considered an urban area of a city in southwest China as the center and a geological field investigation was performed over a total of 282 ​km on three important lifeline projects. The results show: Types of geologic hazards along the highways are mainly avalanches, debris flows, and landslides, respectively. Among them, the landslips are mainly distributed along the roads, with slip, dumping, and wrong break types as the main ones; the debris flows are widely distributed, mainly concentrated in the river valleys; and the unstable slopes are relatively few in number. Geological disasters are characterized by large-scale and concentrated triggering in time and space, and a single disaster can easily trigger other disasters, thus forming a chain of disasters. Neotectonic movement, seismic activity, topography, climatic conditions, stratigraphic lithology, and human activities are important factors leading to geologic hazards in the study area. This study is of great practical significance for reducing the occurrence of roadbed diseases and prolonging the service life of highways.

Place-makers in the digital age: Lifestyle migrants and the emergence of lifestyle-oriented urbanization in China

ABSTRACT The increasing significance of lifestyle migration provides a compelling opportunity for exploring the role that lifestyle migrants play in urban changes. This paper establishes lifestyle migrants as place-makers to comprehend their profound influence on Dali, a city in Southwest China. Three forms of place-making, namely creative, transgressive, and aesthetic place-making, are identified in this paper, which have forged connections between the online and offline worlds and transformed the city into an attractive place for developers, investors, and migrants, thereby giving rise to a distinct mode of urbanization (termed “lifestyle-oriented urbanization” in this paper). By characterizing this urbanization mode and the triad of place-making, this paper illuminates how lifestyle migration has sparked off socio-spatial rearrangements in a peripheral place and how these changes, in turn, have sustained lifestyle migration. Through this exploration, this paper highlights the importance of further research on the interplay between lifestyle migration and urbanization.

Research on the Value of Sludge Resource Utilization in A Sewage Treatment Plant in A Certain City in Southwest China

With the acceleration of urbanization and the improvement of living standards, environmental issues are receiving increasing attention. In recent years, the National Development and Reform Commission and other three departments have issued the "Implementation Plan for Harmless Treatment and Resource Utilization of Sludge", proposing to implement harmless treatment of sludge and promote resource utilization, which is an important measure to build a beautiful China. In order to prevent water pollution and improve environmental quality, the sewage treatment capacity in the Southwest region has rapidly increased, and the sludge production has also sharply increased. The sludge contains various organic pollutants and nutrients, and the resource utilization of sludge has attracted people's attention. Analyzing the properties and nutrients of sludge is a prerequisite for scientific and reasonable sludge resource utilization. Therefore, this article takes sewage treatment plant sludge as the research object, conducts in-depth research on sludge properties and nutrients, and conducts in-depth research on the resource utilization value of sludge.

Effect of Short-Term Exposure to Air Pollutants on Hospital Admissions for End-Stage Renal Disease Patients Undergoing Hemodialysis

To evaluate the association between short-term exposure to air pollutants of end-stage renal disease (ESRD) patients on maintenance hemodialysis and the number of daily hospital admissions. The data on hospitalizations were obtained from the database of the municipal Urban Employees' Basic Medical Insurance and Urban Residents' Basic Medical Insurance of a city in Southwest China. Single and multiple pollutant generalized additive models were utilized to estimate the effect of air pollutants (CO, NO2, O3, PM10, PM2.5, and SO2) on patient admissions after the lag time of different numbers of days. In addition, subgroup analyses stratified by sex, age, PM2.5 and PM10 concentration thresholds, seasonality, and comorbidity status for cardiovascular diseases and hypertension were conducted. In the single pollutant models, the pollutants significantly associated with patient admissions and the corresponding lag time of the strongest association were as follows, every time CO increased by 0.1 mg/m3, there was a 2.39% increase (95% confidence interval [CI]: 0.96%-3.83%) in patient admissions after 7 days of lag time; every time NO2, O3, PM2.5, PM10, and SO2 increased by 10 μg/m3, patient admissions increased by 4.02% (95% CI: 1.21%-6.91%) after 7 days of lag time, 3.57% (95% CI: 0.78%-6.44%) after 0-4 days of lag time, 2.00% (95% CI: 1.07%-2.93%) after 6 days of lag time, 1.19% (95% CI: 0.51%-1.88%) after 7 days of lag time, and 8.37% (95% CI: 3.08%-13.93%) after 7 days of lag time, respectively. In the multiple pollutant model, every time O3 and PM2.5 increased by 10 μg/m3, there was an increase of 3.18% (95% CI: 0.34%-6.09%) in daily patient admissions after 0-4 days of lag time and an increase of 1.85% (95% CI: 0.44%-3.28%) after 7 days of lag time. Furthermore, subgroup analyses showed that seasonality, the severity of air pollution, and patients' comorbidities might be the effect modifiers for the association between ambient air pollution and hospital admissions in ESRD patients receiving maintenance hemodialysis. Air pollution is closely associated with hospital admissions in ESRD patients undergoing maintenance hemodialysis and the strength of this association varies according to seasonality, the severity of air pollution, and patients' status of comorbidities.

Spatiotemporal evolution of habitat quality and its response to landscape patterns in karst mountainous cities: a case study of Guiyang City in China.

Habitat quality heterogeneity is one of the concrete manifestations of landscape pattern changes caused by human activities, which is of great significance to improve habitat quality by optimizing landscape pattern, thus scientifically protecting biodiversity and promoting ecological civilization construction. The coupling of rapid urbanization and ecological restoration measures has had a significant influence on the habitat quality of fragile and fragmented karst mountainous cities in recent years. In this study, spatiotemporal dynamics and heterogeneity of habitat quality and the impact of landscape patterns on habitat quality are analyzed in Guiyang, a typical karst mountain city in southwest China, mainly using the key methodologies such as the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model, Exploratory Spatial Data Analysis (ESDA), and hierarchical partitioning (HP). We found that the habitat quality index of Guiyang City improved from 0.6643 to 0.6988 during 2000-2019; the distribution of habitat quality has significant spatiotemporal heterogeneity and spatial aggregation effect with the low values or the decreased areas concentrated in and around the built-up areas or urbanization expansion areas. Landscape composition had greater contribution than landscape configuration to habitat quality. The increased areas of natural habitat have had a positive effect on habitat quality. Moreover, each landscape configuration had a significant positive or negative correlation with the habitat quality. Therefore, implementing ecological protection and restoration measures in karst mountainous cities might be an effective strategy to improve habitat quality during rapid urbanization. Furthermore, optimizing habitat patterns, reducing the habitats loss, and protecting the natural habitat integrity are crucial to improving and maintaining biodiversity in the study area.

Significant Dynamic Disturbance of Water Environment Quality in Urban Rivers Flowing through Industrial Areas

The urban water environment is seriously affected by human activities. Rivers in highly industrialized areas, which often carry various types of industrial pollutants, such as metals and nutrients, are especially affected. In this study, the water quality of the Pi River, an industrial base that flows through Chengdu, a large city in Southwest China, was tested for one year. Heavy metal concentrations in the water, sediment, and macrobenthic and algal communities in the river were examined. The water pollution index (WPI) and trophic level index (TLI) were employed to measure the water pollution degree and eutrophication status, respectively. The Shannon—Wiener index (H’) and Margalef’s index (dM) were determined to represent the diversity and richness of macroinvertebrates. The principal component analysis (PCA) was employed to define the main heavy metal influencing factors in the Pi River. Our study showed that the eutrophication status increased with spatial change, and the eutrophication status was the most serious in the downstream reach, which was moderately eutrophic. The water body of the Pi River was seriously polluted by heavy metals, and the content of chromium (Cr) in the sediment and cadmium (Cd) in the water/sediment was far beyond the prescribed limit. In addition, we found that Cd had a serious impact on both the benthic and algal communities, and the benthic community structure was completely changed, destroying the original aquatic environment. We explored the mechanisms of the influence of Cd on aquatic fauna, and this information is of great significance for the future conservation of industrial urban rivers. In this study, the spatial–temporal variations in water quality and aquatic communities revealed the pollution status of a river flowing through industrial areas, which provided a basis for future river conservation and restoration.

Pancoriusguiyang sp. nov., a new species of jumping spiders (Araneae, Salticidae) from Guizhou Province, China.

Pancorius Simon, 1902 is a relatively large genus of jumping spider family Salticidae and currently contains 42 valid species that are mainly distributed in South East Asia, 11 of which are recorded from China. A new spider species of the genus Pancorius from Guiyang City in southwest China, is described under the name of P.guiyang Yang, Gu & Yu, sp. nov. Detailed descriptions and photographs are provided. DNA barcodes (a partial fragment of the mitochondrial cytochrome oxidase subunit I gene, COI) of the species were obtained to confirm matching of the sexes and for future use in molecular studies.

Disease burden contributed by dietary exposure to aflatoxins in a mountainous city in Southwest China.

Aflatoxins (AFT) identified as a Group 1 human carcinogen naturally contaminate various types of food and could increase the risk of hepatocellular carcinoma (HCC) through dietary intake. Chongqing municipality is located in Southwest China with subtropical monsoon climate which is conducive to AFT contamination in crops. However, the burden of HCC caused by the dietary exposure of the population in Chongqing to AFT has not been quantified. The burden of HCC was estimated in terms of Disability Adjusted Life Year (DALY) using FDA-iRISK software. Dietary exposure to AFT in three food categories including grain and its products, nuts and seeds, and spices was assessed. The lifetime average daily dose (LADD) of AFT exposure for the population ranged from 2.40 to 8.25 ng/kg bw/day and 9.51 to 15.10 ng/kg bw/day at the mean and heavy (P95) AFT contamination levels, respectively. Among the three food categories, grain and its products contributed most to AFT exposure of the population. The estimated DALYs related to HCC induced by AFT were 162,000-556,000 and 641,000-1,020,000; the DALY rates were 6.47-22.20 and 25.59-40.72 per 100,000 persons per year; and the population attribution fractions (PAF) were 1.68-5.78% and 6.66-10.60%. Although the burden of HCC caused by dietary AFT was estimated to be relatively low among the population, the overall health burden might be underestimated owing to the uncertainties of this dataset. Thus, the overall health burden associated with AFT intake should still be of concern in further studies.

Unexpected association between ambient ozone and adult insomnia outpatient visits: A large-scale hospital-based study

Growing evidence indicates that short-term ozone (O3) exposure has substantial health consequences, but the relationship between short-term ambient O3 and insomnia, a common sleep disorder, is not clear. This study aimed to investigate the short-term effects of ambient O3 exposure on outpatient visits for adult insomnia and to explore the potential modifiers. A large-scale multihospital-based study was carried out in Chongqing, the largest city in Southwest China. Daily data on outpatient visits for adult insomnia, average concentrations of ambient air pollutants and meteorological factors were collected. We conducted quasi-Poisson regression with generalized additive model to assess the association between ambient O3 and outpatient visits for adult insomnia in varied windows of exposure. Subgroup analyses were applied to identify its modifiers. Totally, 140,159 adult insomnia outpatient visits were identified. The daily maximum 8-h average concentration of O3 was 69 μg/m3 during the study period, which greatly below the updated Chinese and WHO recommended limits (daily maximum 8-h average, O3: 100 μg/m3). Short-term O3 exposure was significantly negatively associated with outpatient visits for adult insomnia in different lag periods and the greatest decrease of outpatient visits for adult insomnia was found at lag 02 [0.93% (95% CI: 0.48%, 1.38%)]. Additionally, stronger links between O3 and adult insomnia outpatient visits were presented in cool seasons, and we did not observe any significant modified effects of gender and age. Moreover, the negative O3-insomnia association remained robust after controlling for other common air pollutants and comorbidities. In summary, short-term exposure to lower level of ambient O3, was associated with reduced daily outpatient visits for adult insomnia and such association showed to be more obvious in cool seasons.

Optimization for the Multiday Urban Personalized Trip Design Problem With Time Windows and Transportation Mode Recommendations

The urban tourism market has been increasingly dominated by the demand for personalized experiences. This paper focuses on the multiday urban personalized trip design problem considering the time windows and transportation mode recommendations (MUPTDP-TW-TMR). A two-stage methodology is proposed to solve this problem. In the first stage, a linear programming model for the multiday urban personalized trip design problem with time windows (MUPTDP-TW) is proposed. A modified memetic algorithm (MMA) is devised to solve it, containing efficient operators. In the second stage, a novel transportation mode recommendation model is developed, which considers the diversity of tourist preferences. A modified label-setting algorithm is applied to solve the model. The data from Chongqing, the most popular city in Southwest China, are collected to evaluate the performance of our approach. The case study based on tourist and popular preferences is conducted. Compared with the state-of-the-art algorithms, the experimental results show that our approach can design more reasonable and personalized itineraries for tourists.