Urban Area Of Nanjing Research Articles

Analysis of O3 Pollution Characteristics, Formation Sensitivity, and Transport Impact in Southern Nanjing

As one of the most important city clusters in China, surface ozone (O3) pollution in the Yangtze River Delta (YRD) Region has become a prominent air quality problem in recent years. Online observations of ambient O3, nitrogen oxides (NOx), and volatile organic compounds (VOCs) were conducted in southern Nanjing from July-September 2020 and April-May 2021. On this basis, the pollution characteristics of O3 were analyzed. The O3-VOCs-NOx sensitivity and the transport influence of its precursors were further discussed using models. The frequency statistics of the daily maximum 8-hour moving average (DMA-8h O3) and hourly concentration (O3-1h) showed that O3 pollution in southern Nanjing was more serious than that in urban areas. Three typical O3 pollution episodes were selected during the whole observation period, which included August 16th-27th, 2020; September 3rd-11th, 2020; and May 17th-25th, 2021. The O3-VOCs-NOx sensitivities in these three pollution episodes were analyzed using the observation-based model (OBM). The results of the relative incremental reactivity (RIR) and empirical kinetics modeling approach (EKMA) showed that the sensitivities of O3 formation in the three pollution episodes were in the NOx-limited regime, the transition regime, and the VOCs-limited regime, respectively. This difference in O3-VOCs-NOx sensitivity reflects that the site may have been influenced by transport. Therefore, the potential source contribution function (PSCF) and the concentration weighted trajectory (CWT) method were further used to analyze the potential source areas of NOx, VOCs, and O3 in these three pollution episodes. The results showed that there were obvious regional transport effects of NOx, VOCs, and O3 in these three pollution episodes. The location of potential sources differed in these three pollution episodes, which were affected by the eastern cities of the Lishui site; the urban area of Nanjing and eastern area of Anhui Province; and the urban area of Nanjing and the middle of the YRD Region, respectively. The impact of transport on O3 and its precursors also indicated the necessity of regional joint prevention and control of O3 pollution in the YRD Region.

Phonological processes in initial consonants of Putonghua in children in Jiangsu urban areas

Objective: To explore the phonological processes in initial consonants of Putonghua-speaking children in Jiangsu urban areas. Methods: A status survey was applied. From December 2014 to September 2015, a stratified random sampling method was used to select 958 children aged 1 to 6 years with Putonghua as their mother tongue in the urban area of Nanjing, Changzhou, Yangzhou and Xuzhou to examine their phonological performance. Speech samples were collected by the method of picture naming. The children were divided into 9 age groups (1.5-<2.0, 2.0-<2.5, 2.5-<3.0, 2.5-<3.0, 3.0-<3.5, 3.5-<4.0, 4.0-<4.5, 5.0-<6.0, 6.0-<7.0 years). Descriptive analysis method was used to analyze the phonological processes in initial consonants at different age groups. Results: Among the 958 children, there were 482 boys and 476 girls. The age of the children was (3.8±1.4) years. The number of children in the 9 age groups (1.5-<2.0, 2.0-<2.5, 2.5-<3.0, 2.5-<3.0, 3.0-<3.5, 3.5-<4.0, 4.0-<4.5, 5.0-<6.0, 6.0-<7.0 years) is 100, 110, 110, 114, 114, 114, 111, 119, and 66, separately. The process of substitution was found in the speech of 701 children (73.2%), syllable structure simplification was found in 194 children (20.3%), distortion was found in 41 children (4.3%), and assimilation was found in 17 children (1.8%). Among these 4 types of processes, the occurrence of substitution was highest in all the age groups, ranging from 30.3% (20/66) to 94.5% (104/110). The occurrence of syllable structure simplification ranged from 27.3% (30/110) to 91.0% (91/100) in the age groups of 1.5-<3.0 years and 0.9% (1/114) to 7.9% (9/114) in the age groups of 3.0-<7.0 years. The occurrence of distortion ranged from 7.3% (8/110) to 19.1% (21/110) in the age groups of 1.5-<3.0 years and 0 (0/114) to 2.7% (3/111) in the age groups of 3.0-<7.0 years. The occurrence of assimilation was very low in all age groups, ranging from 0 (0/114) to 3.0% (3/100) among all age groups. For substitution, the occurrence order of mainly individual processes from high to low was listed as follows: retroflexion 35.4% (339/958), deretroflexion 31.6% (303/958), lateralization 27.9% (267/958), stopping 17.8% (171/958), backing 14.2% (136/958), palatalization 10.9% (104/958), fronting 10.6% (102/958), and nasalization 5.8% (56/958). From the 4.0-<4.5 years of age group onwards, the phonological processes in initial consonants all met suppression criteria (the occurrence of processes was reduced to<10%) except retroflexion, deretroflexion, and lateralization. Conclusions: The processes of syllable structure simplification and distortion mainly appears in the early stage of speech sound development, while substitution is the major form of phonological pattern in initial consonants found in developmental speech errors. By 4 years of age, phonological processes in initial consonants almost disappear. The remaining processes that persisted for a longer period of time are retroflexion, deretroflexion, and lateralization.

Evolution of PM2.5 Chemical Composition and Sources in Nanjing During the Implementation of the APPCAP

To acquire a deeper understanding about the impact of the Air Pollution Prevention and Control Action Plan (APPCAP) on ambient fine particulate matter (PM2.5), measurements of PM2.5 chemical components were conducted in the urban area of Nanjing during the implementation of the APPCAP. Evolution characteristics of several properties of the PM2.5 were studied, including the concentrations, proportions, and enrichment factors of major PM2.5 components and the acidity of the PM2.5. In addition, the source apportion of the PM2.5 was analyzed using the positive matrix factorization (PMF) model. The results showed that during the implementation of the APPCAP, the proportion of sulfate (SO42-) in PM2.5 decreased, whereas the proportions of nitrate (NO-3) and ammonium (NH+4) increased significantly together, from 25.58% in 2014 to 37.15% in 2017. The concentrations of carbon components (OC and EC) decreased in the early stage of the APPCAP; however, the decreasing trend slowed down in the later stage. In particular, the proportion of organic carbon (OC) increased, especially for the secondary organic carbon (SOC). The acidity of the PM2.5 decreased significantly, with the molar equivalent ratio of cations and anions increasing from 0.83 in 2014 to 1.13 in 2017. The contributions of coal combustion and the metallurgical and petrochemical industry to the PM2.5 generally showed a downward trend, whereas the contribution of vehicle emissions increased rapidly, from 8.78% in 2014 to 13.92% in 2017. The contribution of general fugitive dust fluctuated greatly, but that of soil fugitive dust showed an upward trend. This study suggested that the direct PM2.5 emissions, such as those from coal combustion and industries, were effectively controlled during the implementation of the APPCAP; however, the contribution of secondary aerosols became increasingly prominent, which indicates that future policies of PM2.5 pollution control should focus on emission reduction of the precursors such as NOx, NH3, and VOCs. In addition, the effects of increasing alkalization of the PM2.5 and enhanced oxidizability of the atmosphere on the PM2.5 pollution also require further attention.

Measuring spatial accessibility to refuge green space after earthquakes: A case study of Nanjing, China.

The construction of refuge spaces in rapidly urbanizing historic cities is a challenging task owing to their complex urban form, unique urban fabric, and historic preservation requirements. Refuge green space (RGS) is a green space that can serve as an emergency shelter in cities, providing a flexible means to increase the emergency shelter capacity for rapidly urbanized historic cities. After major earthquakes, spatial accessibility to GRSs is a critical planning strategy for disaster prevention and emergency response in historic cities. To match the RGS planning with the emergency service demand, we must examine the spatial disparity in access to existing RGSs. In this study, the urban area of Nanjing was selected as the target region to analyze the spatial disparity in access to RGSs using the Gaussian two-step floating catchment area method at four evacuation times (10, 20, 30, and 60 min). The results showed that the spatial accessibility exhibited clustering characteristics, where high-accessibility spaces were mainly distributed in the northern and southern regions of Nanjing. The increase in the evacuation time improved accessibility to RGSs, but the existing RGSs still could not sufficiently satisfy the emergency shelter needs of citizens. Based on the bivariate local Moran’s I analysis of the RGS accessibility and population density, the spatial mismatch regions were dominant in the center of the urban area. These findings not only are expected to assist emergency planners by improving their strategic plans for emergency shelter investment in Nanjing and their ability to respond to catastrophic earthquakes, but also provide a strong reference for the construction of a safe environment in other rapidly developing historic cities that face earthquake threats.

Analysis of Travel Hot Spots of Taxi Passengers Based on Community Detection

It is an important content of smart city research to study the activity track of urban residents, dig out the hot spot areas and spatial interaction patterns of different residents’ activities, and clearly understand the travel rules of urban residents' activities. This study used community detection to analyze taxi passengers’ travel hot spots based on taxi pick-up and drop-off data, combined with multisource information such as land use, in the main urban area of Nanjing. The study revealed that, for the purpose of travel, the modularity and anisotropy rate of the community where the passengers were picked up and dropped off were positively correlated during the morning and evening peak hours and negatively correlated at other times. Depending on the community structure, pick-up and drop-off points reached significant aggregation within the community, and interactions among the communities were also revealed. Based on the type of land use, as passengers' travel activity increased, travel hot spots formed clusters in urban spaces. After comparative verification, the results of this study were found to be accurate and reliable and can provide a reference for urban planning and traffic management.

Characteristics of carbonaceous aerosols in ambient PM2.5 during the COVID-19 period in Nanjing

In order to explore the variations of carbon components[including organic carbon (OC) and element carbon (EC)] in PM2.5 at the urban area of Nanjing during the breakout of COVID-19 period, PM2.5, OC and EC mass concentrations were measured by online monitoring from January to February 2020. Compared to the concentrations before the emergency response, the PM2.5 concentration after the emergency response was reduced by 41.2% and EC reduced by 57.9%. These results indicate that the shutdown significantly reduced PM2.5 and EC concentrations, but the OC concentration increased. Before the emergency response, the OC and EC concentrations were low in daytime and high at night and early morning. After the emergency response, the average concentration of EC only had a slight change within a day and maintained at low concentration level, OC showed a curve trend which was higher in the afternoon and lower in morning and evening. The significant decrease of PM2.5 concentration after the emergency response period led to the increasing of light radiation intensity, which promoted the formation of secondary organic carbon (SOC). The SOC concentration increased when the PM2.5 and EC concentrations decreased, and the correlation between OC and EC also decreased significantly. © 2021, China Environmental Science Press. All rights reserved.

Evaluating Street Greenery by Multiple Indicators Using Street-Level Imagery and Satellite Images: A Case Study in Nanjing, China

Street greenery plays an essential role in improving the street environment and residents’ health. The evaluation of street greenery is of great value to establish environmentally friendly streets. The evaluation indicators of present studies evaluating street greenery were relatively single, either the Green View Index (GVI) or Normalized Difference Vegetation Index (NDVI), which cannot describe the greenery condition in its entirety. The objective of this study is to assess the street greenery using multiple indicators, including GVI, NDVI, and Vegetation Structural Diversity (VSD). We combined street view images with a semantic segmentation method to extract the GVI and VSD and used satellite images to calculate the NDVI in the urban area of Nanjing, China. We found correlations and discrepancies of these indicators using statistical analyses in different urban districts, functional areas, and road levels. The results indicate that: (1) the GVI and NDVI are strongly correlated in open spaces, whereas weakly correlated in residential and industrial lands, (2) the areas with higher VSD are mainly located in the new city, whereas the VSD in the old city is lower, and a weak negative correlation exists between the GVI and VSD in the research area, and (3) the old city has a higher GVI level compared to the new city on the main road, whereas the new city has a higher GVI level than the old city on the branch road. Compared with the GVI, the trend of VSD in the old city and the new city is relatively consistent. Our findings suggest that considering multiple indicators of street greenery evaluation can provide a comprehensive reference for building more human-friendly and diversified street green belts.

Spatio-Temporal Visualization Method for Urban Waterlogging Warning Based on Dynamic Grading

With the acceleration of the urbanization process, the problems caused by extreme weather such as heavy rainstorm events have become more and more serious. During such events, the road and its auxiliary facilities may be damaged in the process of the rainstorm and waterlogging, resulting in the decline of its traffic capacity. Rainfall is a continuous process in a space–time dimension, and as rainfall data are obtained through discrete monitoring stations, the acquired rainfall data have discrete characteristics of time interval and space. In order to facilitate users in understanding the impact of urban waterlogging on traffic, the visualization of waterlogging information needs to be displayed under different spatial and temporal granularity. Therefore, the appropriateness of the visualization granularity directly affects the user’s cognition of the road waterlogging map. To solve this problem, this paper established a spatial granularity and temporal granularity computing quantitative model for spatio-temporal visualization of road waterlogging and the evaluation method of the model was based on the cognition experiment. The minimum visualization unit of the road section is 50 m and we proposed a 5-level depth grading method and two color schemes for road waterlogging visualization based on the user’s cognition. To verify the feasibility of the method, we developed a prototype system and implemented a dynamic spatio-temporal visualization of the waterlogging process in the main urban area of Nanjing, China. The user cognition experiment showed that most participants thought that the segmentation of road was helpful to the local visual expression of waterlogging, and the color schemes of waterlogging depth were also helpful to display the road waterlogging information more effectively.

Design of a Super Wide Band Antenna and Measure of Ambient RF Density in Urban Area

A compact Super Wide band (SWB) antenna fed by coplanar waveguide (CPW) is proposed in this paper. The size of the antenna is 140 × 100mm 2 (0.16λ × 0.12λ). The antenna originates from 3D volcano smoke antenna, and consists of a prolonged radiation patch and a symmetrical ground. Both the patch and ground were designed as smoothing structure, which can improve the impedance matching through a wide band. The simulated and measured bandwidth show that the antenna has a well-matched impedance bandwidth from 400MHz to higher than 20GHz under VSWR = 2 criterion, and the bandwidth ratio is greater than 50:1. The gain, efficiency and radiation pattern were all measured, and the maximum gain and efficiency are 6.3dBi and 96%, respectively. The antenna was also used to measure the ambient radiation frequency (RF) density in an urban area of Nanjing in China, which on the other hand proves the efficiency of this design.

Polycyclic aromatic hydrocarbons and heavy metals in urban environments: Concentrations and joint risks in surface soils with diverse land uses

AbstractAlthough polycyclic aromatic hydrocarbons (PAHs) and heavy metals (HMs) are abundant around cities, few researchers have studied the complex concentrations and joint risks of these pollutants in urban surface soils containing diverse land uses. We collected 69 urban surface soil samples from roadside districts, green belts, public green space, commercial districts, and residential district in urban areas of Nanjing, China to determine the concentrations, distributions, deposition patterns, and joint risks of PAH and HM contaminants. No significant differences were found among the five studied land uses, but a wide range of PAH levels were found in these land uses, as these diverse land uses have similar PAH pollution sources. As these areas persistently generate high PAH levels by gasoline/diesel engine or coal combustion, the PAH distribution characteristics indicated that commercial centers or city centers are the most heavily contaminated sites. The distributions of black carbon and HMs, except for Pb, were found to be significantly correlated. Except for Cd and As, HM levels among diverse land uses also showed no significant differences, possibly stemming from the non‐point source pollution of these metals in the study areas. Factor analysis showed that 46.2% of the elevated pollutant concentrations resulted from combustion processes, 24.3% were caused by natural background fluctuations, and 11.9% resulted from non‐combustion processes. The studied PAHs and As presented low carcinogenic risks. Cd, Cu, Pb, and Zn depicted acceptable total non‐carcinogenic risks in all land uses; however, the risks associated with these HMs possessed detailed differences.

The association between residential density and physical activity among urban adults in regional China

BackgroundStudies from Western countries reported a positive relationship between residential density (RD) and physical activity (PA) among adults. There was no such study from China, a rapidly-urbanizing country in the world. This study aimed to investigate the RD-PA association among urban adults in China.MethodsA multistage sampling approach was used to randomly select participants (aged 35–74 years old) in urban areas of Nanjing in 2017. The outcome variable was PA (dichotomized into “sufficient” or “insufficient”), while the independent variable was RD (tertiled into three sub-groups). Odds ratios (OR) and 95% confidence interval (CI) were computed to examine the RD-PA association using mixed-effects logistic regression models with adjustment for age, sex, nationality, marriage, educational attainment, employment status, body weight status, green space and neighborhood-level clustering effects.ResultsOf the 1568 eligible participants, 1551 were interviewed (response rate = 98.9%), with the mean age (standard deviation) of 54.7 (11.1) years old, and 46% of men. After adjustment for potential confounders and community-level clustering effects, participants lived in communities with higher (OR = 0.31, 95% CI = 0.21, 0.47) and middle (OR = 0.70, 95% CI = 0.50, 0.99) residential density were significantly less likely to achieve sufficient physical activity relative to their counterparts lived in the lower densed communities. Similar negative RD-PA association was examined for men or women, separately. The difference in the ORs between the middle and higher RD tertiles was also statistically significant (P < 0.01).ConclusionsA negatively gradient RD-PA association, independent of body weight status and green space, was observed among urban adults in regional China. It has public health implications for China to help residents’ promote and maintain physical activity through planning and constructing PA−/health-friendly built environment in future.

Residential density was negatively associated with excess body weight among adults in an urban region of China.

BackgroundResidential density was found to be associated with excess body weight among adults in Western societies but it remains unclear in China. We aimed to explore the relationship between residential density and excess body weight among adults in China.MethodsThis cross-sectional study was conducted in 2017 in urban areas of Nanjing, China. A multi-stage sampling method was used to randomly select participants aged 35–74 years from 8 urban neighborhoods in Nanjing. Status of excess body weight was the outcome variable which was categorized as "yes (BMI≥24)" or "no (BMI<24)" according to specific recommendations for Chinese adults. Residential density was the main explanatory variable which was grouped into tertiles. Odds ratios (OR) and 95% confidence interval (CIs) were calculated to assess the relationship between residential density and excess body weight using mixed-effects regression models after adjusting for age, sex, education, occupation, marital status, redmeat, smoking, physical activity, diabetic status and potential neighborhood-level clustering effect.ResultsA total of 1551 participants were recruited with a response rate of 98.9% (1551/1568). The mean age (standard deviation) of participants was 54.7 (11.1) years, and 46% of them were men. With adjustment for potential influential factors, participants in neighborhoods with lower (OR = 1.38, 95% CI = 1.06–1.81) and middle (OR = 1. 29, 95% CI = 1. 01, 1. 64) tertile of residential density were at significantly higher risk of gaining excess body weight relative to their counterparts in communities with upper tertile of residential density. Such a negative association between residential density and excess body weight was observed for men only after stratified analysis by gender.ConclusionsA negative association between residential density and excess body weight was identified in overall and male urban Chinese adults, and the association was independent of physical activity. Results of our study have important implications in guiding public health policy making regarding prevention of excess body weight at community level via establishment of health-friendly neighborhood environment in China.

Seasonal characteristics and health risks of PM2.5-bound organic pollutants in industrial and urban areas of a China megacity

Organic pollutants are important harmful components in atmospheric fine particulate matters (PM2.5), health risks of which varied with temporal and spatial distributions. To clarify the characteristics of atmospheric organic pollution, the concentrations, sources, and human health risks of typical organic compositions in PM2.5 samples from both industrial and urban areas of Nanjing in eastern China were investigated monthly for a year. Results showed that, the concentrations of PM2.5-bound polycyclic aromatic hydrocarbons (PAHs) and n-alkanes were higher in winter and spring than those in summer and autumn. The organic pollution was slightly higher in industrial than urban area, though the PAHs in autumn and the n-alkanes in warm season (summer and autumn) were higher in urban area. With regards to the pollutant sources, the atmospheric PAHs were dominated by motor vehicle exhaust in the urban area, and combined with coal combustion emission in the industrial area. Airborne n-alkanes were mainly from biological source accompanied by fossil fuel combustion in industrial area. The PM2.5-bound PAHs indicated higher risks to adults in industrial area than in urban area with the seasonal patterns: winter > spring > autumn > summer. More attention should be paid to the health risks of exposure to organic pollutants accumulated in PM2.5 during cold season. Controlling vehicle emissions might be the key measure for alleviating atmospheric PAHs and n-alkanes pollution in megacities, while coal purification can be an effective control method in industrial areas.

Primary and secondary sources of ambient formaldehyde in the Yangtze River Delta based on Ozone Mapping and Profiler Suite (OMPS) observations

Abstract. Formaldehyde (HCHO) in the ambient air not only causes cancer but is also an ideal indicator of volatile organic compounds (VOCs), which are major precursors of ozone (O3) and secondary organic aerosol (SOA) near the surface. It is meaningful to differentiate between the direct emission and the secondary formation of HCHO for HCHO pollution control and sensitivity studies of O3 production. However, understanding of the sources of HCHO is still poor in China, due to the scarcity of field measurements (both spatially and temporally). In this study, tropospheric HCHO vertical column densities (VCDs) in the Yangtze River Delta (YRD), East China, where HCHO pollution is serious, were retrieved from the Ozone Mapping and Profiler Suite (OMPS) onboard the Suomi National Polar-orbiting Partnership (Suomi-NPP) satellite from 2014 to 2017; these retrievals showed good agreement with the tropospheric HCHO columns measured using ground-based high-resolution Fourier transform infrared spectrometry (FTS) with a correlation coefficient (R) of 0.78. Based on these results, the cancer risk was estimated both nationwide and in the YRD region. It was calculated that at least 7840 people in the YRD region would develop cancer in their lives due to outdoor HCHO exposure, which comprised 23.4 % of total national cancer risk. Furthermore, the contributions of primary and secondary sources were apportioned, in addition to primary and secondary tracers from surface observations. Overall, the HCHO from secondary formation contributed most to ambient HCHO and can be regarded as the indicator of VOC reactivity in Hangzhou and in urban areas of Nanjing and Shanghai from 2015 to 2017, due to the strong correlation between total HCHO and secondary HCHO. At industrial sites in Nanjing, primary emissions more strongly influenced ambient HCHO concentrations in 2015 and showed an obvious decreasing trend. Seasonally, HCHO from secondary formation reached a maximum in summer and a minimum in winter. In the spring, summer, and autumn, secondary formation had a significant effect on the variation of ambient HCHO in urban regions of Nanjing, Hangzhou, and Shanghai, whereas in the winter the contribution from secondary formation became less significant. A more thorough understanding of the variation of the primary and secondary contributions of ambient HCHO is needed to develop a better knowledge regarding the role of HCHO in atmospheric chemistry and to formulate effective control measures to decrease HCHO pollution and the associated cancer risk.

Composition and Atmospheric Reactivity of Ambient Volatile Organic Compounds(VOCs)in the Urban Area of Nanjing, China

Online gas chromatography with flame ionization detection (GC-FID) systems were employed to observe 56 species of volatile organic compounds (VOCs) in the environmental atmosphere in Nanjing in 2015. The results showed that the annual volume fraction of VOCs was (17.49±11.35)×10-9. The highest concentration of VOCs was in April (22.21×10-9), and the lowest in July (12.39×10-9). Diurnal values of VOCs concentration had no obvious variations. Alkanes, alkenes, aromatics, and acetylene accounted for 56.51%, 11.06%, 24.62%, and 7.81%, respectively. Propane (15.26%), ethane (14.14%), acetylene (7.81%), toluene (6.97%), n-butane (6.23%), ethylene (5.23%), isobutane (4.34%), propylene (4.13%), isoprene (4.12%), and m/p-xylene (4.06%) were the most abundant VOCs species. The average ratio of toluene/benzene (T/B) was 2.02, indicating that the atmospheric VOCs were mainly affected by emissions of motor vehicles, especially gasoline vehicles. The average ratio of ethane/ethyne (E/E) was 2.24, showing that the plume had aged. The hydroxyl radical (·OH) loss rate(L·OH) and ozone formation potential(OFP)were applied to assess the chemical reactivity of VOCs. The atmospheric activity of VOCs was higher in the winter and spring than in the summer and autumn. Aromatics and alkenes were the most important contributors to L·OH and OFP. Their contributions to L·OH and OFP were 46.96% and 41.58%, and 33.73% and 39.86%, respectively. Propylene, ethylene, and xylene were the most active species.

Risk Reduction Behaviors Regarding PM2.5 Exposure among Outdoor Exercisers in the Nanjing Metropolitan Area, China.

Aims: This study aimed to describe risk reduction behaviors regarding ambient particulate matter with a diameter of 2.5 μm or less (PM2.5) among outdoor exercisers and to explore potential factors influencing those behaviors in the urban area of Nanjing, China. Method: A cross-sectional convenience sample survey was conducted among 302 outdoor exercisers in May 2015. Descriptive analysis was used to describe demographics, outdoor physical activity patterns, knowledge of PM2.5 and risk reduction behaviors. Multivariate logistic regression analysis was then used to explore factors that influence the adoption of risk reduction behaviors. Results: The most common behavior to reduce PM2.5 exposure was minimizing the times for opening windows on hazy days (75.5%), and the least common one was using air purifiers (19.3%). Two thirds of respondents indicated that they wore face masks when going outside in the haze (59.5%), but only 13.6% of them would wear professional antismog face masks. Participants adopting risk reduction behaviors regarding PM2.5 exposure tended to be females, 50–60 year-olds, those with higher levels of knowledge about PM2.5 and those who had children. Conclusions: These findings indicate the importance of improving knowledge about PM2.5 among outdoor exercisers. Educational interventions should also be necessary to guide the public to take appropriate precautionary measures when undertaking outdoor exercise in high PM2.5 pollution areas.

Diversity of bryophytes in urban area of Nanjing, China

Bryophytes are morphologically special higher plants, with unique ornamental values and a wide application prospect. Its species richness was just secondary to angiosperms. To more effectively utilize bryophytes for greening and landscape construction, 77 plots in 10 green spaces were investigated in urban area of Nanjing. 55 species belonging to 36 genera and 21 families were recorded, among which Pottiaceae and Thuidiaceae were widely distributed. The species richness in green space gradually reduced from the center to the surrounding areas of the city. The 10 green spaces could be clustered into three groups based on bryophyte diversity, habitats, human distur-bance frequency, green space areas. Results from Canonical correspondence analysis (CCA) showed that canopy density, humidity, and substrate types were the major environmental factors the distribution of bryophytes. In Nanjing, most bryophytes preferred to grow in moderate humidity and open areas.

Re-look at socioeconomic inequalities in stroke prevalence among urban Chinese: is the inflexion approaching?

BackgroundThe present association between socioeconomic status (SES) and stroke is positive in developing communities, but it is negative in developed countries where a positive SES-stroke relationship was recorded several decades ago. We hypothesized that the SES-stroke relationship in developing societies mirrors the trajectory of the Western countries at some stage of economic development. This study aimed to examine whether this inflexion is approaching in China.MethodsThis study comprises of two cross-sectional surveys conducted in the same urban areas of Nanjing, China in 2000 (S2000) and 2011 (S2011) using the same selection criteria (i.e., aged≥35 years) and sampling approach. Physician-diagnosed stroke was the outcome event, while family average income (FAI) was the explanatory variable and tertiled in our anlaysis. Mixed-effects models were used to examine the FAI-stroke association.ResultsOverall, 19,861 (response rate = 90.1%) and 7824 (response rate = 82.8%) participants participated in the S2000 and S2011, respectively. The prevalence of stroke increased by 2.5-folds (95%CI = 2.2, 2.9) from 2000 (2.1%, 95%CI = 1.9%, 2.3%) to 2011 (5.1%, 95%CI = 4.6%, 5.6%) (p < 0.01). Compared with the lower FAI category, the positive association between stroke prevalence and the higher FAI group decreased from 1.99 (95%CI = 1.55, 2.56) in 2000 to 1.49 (95%CI = 1.09, 2.03) in 2011 after control for potential confounders. A similar pattern was also observed for the middle FAI group (1.60, 95% CI = 1.23, 2.08 in 2000 vs. 1.37, 95%CI = 1.01, 1.88 in 2011).ConclusionsThis study revealed that socioeconomic inequalities in stroke were diminishing in regional China during the recent 11-year period, although the SES-stroke association was still positive. Tailored intervention against stroke should currently target on SES-vulnerable people.

Exploring unobserved heterogeneity in bicyclists’ red-light running behaviors at different crossing facilities

Bicyclists running the red light at crossing facilities increase the potential of colliding with motor vehicles. Exploring the contributing factors could improve the prediction of running red-light probability and develop countermeasures to reduce such behaviors. However, individuals could have unobserved heterogeneities in running a red light, which make the accurate prediction more challenging. Traditional models assume that factor parameters are fixed and cannot capture the varying impacts on red-light running behaviors. In this study, we employed the full Bayesian random parameters logistic regression approach to account for the unobserved heterogeneous effects. Two types of crossing facilities were considered which were the signalized intersection crosswalks and the road segment crosswalks. Electric and conventional bikes were distinguished in the modeling. Data were collected from 16 crosswalks in urban area of Nanjing, China. Factors such as individual characteristics, road geometric design, environmental features, and traffic variables were examined. Model comparison indicates that the full Bayesian random parameters logistic regression approach is statistically superior to the standard logistic regression model. More red-light runners are predicted at signalized intersection crosswalks than at road segment crosswalks. Factors affecting red-light running behaviors are gender, age, bike type, road width, presence of raised median, separation width, signal type, green ratio, bike and vehicle volume, and average vehicle speed. Factors associated with the unobserved heterogeneity are gender, bike type, signal type, separation width, and bike volume.

Sugar-sweetened beverages and school students' hypertension in urban areas of Nanjing, China.

Literature showed that sugar-sweetened beverages (SSBs) could increase the risk of developing hypertension in school students, but there is no reported evidence from China yet, so this study aims to investigate the association of the SSBs consumption and school students' hypertension in urban areas of Nanjing, China. A cross-sectional survey was conducted among primary and junior high school students selected from 32 primary schools and 16 junior high schools using a multi-stage random sampling method, with a total number of 10,091 participants involved. The mean age of Grade 4 is 9.04 ± 0.38, while the mean age of Grade 7 is 12.03 ± 0.41. Blood pressure was measured and SSBs consumption was reported using a validated questionnaire. The overall prevalence of hypertension was 4.5% among the participants. After adjustment for school, parental education, physical activity, diet intake including meat and snacks, participants who had an experience of SSBs intake were at a higher risk of developing hypertension (odds ratio (OR) = 1.40, 95% confidence interval (CI) = 1.15, 1.70) compared with those who had no experience of SSBs intake. A significant association between the consumption of SSBs and hypertension was observed among the students who were at a healthy weight (OR = 1.78, 95% CI = 1.20, 2.65), as well as who were overweight or obese (OR = 1.28, 95% CI = 1.01, 1.61). SSBs may play a contributing role in developing childhood hypertension in this population in China, which is of important implications for future population-based childhood hypertension intervention in China and other countries.