Based on the monthly data of 12 months in 30 major cities and combined with the monthly data of the air quality index (AQI) in 30 major cities, this paper analyzed the quality of human settlements in 2015 with the ArcGIS spatial analysis method. On the basis of the quality of air in this analysis, the coupling degree of the five great systems in these human settlements was also calculated. The finding shows that (1) according to the spatial distribution of the human settlements quality index in the main cities, the quality of urban human settlements was gradually decreased from the coastal regions to northwest inland regions, presenting an overall look that the quality was high in the south and low in the north, which converged to the change of the air quality; (2) the human settlements quality index apparently changed with season variation. A significant difference was found in the fourth quarter, and the biggest deviation among cities in China was up to 0.680, while the smallest deviation in the second quarter was 0.448; and (3) on the basis of factors that influenced the quality index, related kinds of norms in the main cities were built in the five great systems of human settlements, and the evaluated coupling degree between the five systems was at the antagonistic stage.
Since the reform and opening up, as the second largest economy in the world, China’s air quality is the second lowest in the world as a whole, which has a tremendous negative impact on the urban human settlements in China [
At present, foreign scholars carried out a number of studies related to air quality: (1) the impact of air quality on health: foreign scholars evaluate air quality to determine the relationship between the mortality rate and respiratory disease and air quality [
A variety of methods for air quality research are put forward by domestic and foreign scholars: (1) using fuzzy logic to deal with air quality indicators [
Human settlements science involves many disciplines. Since the 20th century, the study area of urban human settlements has been continuously expanded. The interdisciplinary contents and methods of study carefully analyze human settlements and related factors. From the perspectives of sociology [
Building harmonious and livable cities is an important content in the thirteenth Five-Year Plan for which health is a basic requirement [
Because of the unpublicized data in Tibet Autonomous Region and different monitoring systems and standards in Taiwan Province, Hong Kong SAR and Macao SAR, the air quality indexes of 30 major cities in the provincial level except the four regions above are analyzed in this paper. The main data are AQI monthly figures around provided by the official website of the Ministry of Environmental Protection (
According to the concentration limit of the AQI (GB3095-2012) and various pollutants concentration limits, the Individual Air Quality Index (IAQI) can be drawn by separate calculation on the measured concentration of pollutants (among them, PM10 and PM2.5 are the average concentration of 24 hours):
The second step is to select the maximum value from the IAQI of various pollutants as the AQI.
Normalized in positive, negative, and moderate indicators, the range of the data for each variable will be between [0, 1] and the data are pure numbers without units.
Positive indicator:
Negative indicator:
Appropriate indicators:
Referring to the domestic and international research on the indicator system of urban human settlements, following the general principles of scientificity, validity, objectivity, and integrity of the indicator system and basing on the indicators, the environmental system, social system, residential system, supporting system, and human system which constitute the human settlements were established [
Evaluation index system of the urban human settlements environment.
Target layer |
Target layer weight | Criterion layer |
Weight of the criterion layer | Index |
Index level weight |
---|---|---|---|---|---|
Environmental system |
0.2932 | The natural environment |
0.1433 | Air quality index |
0.0568 |
Relative humidity |
0.0426 | ||||
Average wind speed |
0.0439 | ||||
Social environment |
0.1499 | Per capita public green area |
0.0586 | ||
The growth of gas and LPG mining industry |
0.0395 | ||||
Industrial soot (powder) and dust processing rate |
0.0518 | ||||
|
|||||
Social system |
0.2060 | Economic benefits |
0.1090 | Energy consumption per unit of GDP |
0.0551 |
Gross value of industrial output |
0.0539 | ||||
Economic structure |
0.0970 | GDP proportion of the secondary industry |
0.0485 | ||
GDP proportion of the third industry |
0.0485 | ||||
|
|||||
Living system |
0.1309 | Living standard |
0.1309 | Consumer price index |
0.0344 |
Urban residents’ per capita consumption expenditures |
0.0394 | ||||
The number of cars per unit |
0.0571 | ||||
|
|||||
Support system |
0.3026 | Energy-saving and environmental protection |
0.1034 | Energy-saving and environmental protection financial expenditure |
0.0569 |
Transport costs per capita |
0.0465 | ||||
Polluting emissions |
0.1992 | Passenger turnover |
0.0527 | ||
Freight turnover |
0.0527 | ||||
Industrial SO2 emissions |
0.0467 | ||||
Industrial (powder) dust emissions |
0.0471 | ||||
|
|||||
Human system |
0.0673 | Resident composition |
0.0673 | Population density |
0.0332 |
The rate of urbanization |
0.0341 |
The quality of urban human settlements reflects the overall state of human settlements in a certain period and is a comprehensive index to measure the human settlements of urban residents. According to Zhang Zhi’s characteristics of the indicator system, the human settlements quality index can be weighted comprehensively as follows [
Ratings and index.
Ratings | Level I | Level II | Level III | Level IV | Level V |
---|---|---|---|---|---|
Index ( |
0.69 ≤ |
0.6 ≤ |
0.45 ≤ |
0.3 ≤ |
0.1 ≤ |
Condition | A | B/C | D | E | F |
In terms of space, city human settlements’ every quality difference in the quality of the urban human settlements environment within their jurisdiction and China’s 30 qualities of the urban human settlements environment were classified into five grades according to their numerical size by Jenks, using ArcGIS spatial analysis in China on the map. This can be a more intuitive analysis based on the air quality of urban residential environment quality differentiation and the four quarters’ (the first quarter: March–May, the second quarter: June–August, the third quarter: September–November, and the fourth quarter: December–next February) evolution of spatial differentiation [
Urban human settlements coupling is given as follows:
Based on the human settlements system coupling model, a coupling degree (
Coupling degree classification and coupling level of the human settlements system.
Coupling values | Coupling stage | Coupling characteristics |
---|---|---|
0 < |
Low-level coupling | Primary development of socioeconomic and infrastructure; poor natural environment carrying capacity |
0.3 < |
Antagonistic coupling | Rapid development of social and economy; the increasing contradiction between the natural environment and human society |
0.5 < |
Run-in phase | A benign coupling stage of systems |
0.8 < |
High-level coupling | Mutual promotion and development among systems |
According to the time sequence, the quality of human settlements in China’s major cities showed a significant difference not between the first quarter and the third quarter as a whole but between the first quarter and the fourth quarter (Figure
Spatial distribution of the human settlements quality index in provincial capitals: (a) the first quarter; (b) the second quarter; (c) the third quarter; (d) the fourth quarter.
In the four quarters (Figure
Quarterly change of the urban human settlements quality index.
It can be seen from the analysis that the quality of human settlements in the Northeast China and North China has changed a lot during the year, which is relatively poor in the fourth quarter. At the same time, it is generally good in the southern cities whose difference is not particularly obvious within one year. According to the air quality index of 30 major cities in 2015, ranking of human settlements quality approximates that of air quality, which shows that the research of air quality contributes to the evaluation of human settlements quality and the study on the coupling degree of the human settlements system.
The coupling degree of the human settlements system in 30 cities in China was calculated with the use of the coupling degree calculation model. Meanwhile, according to the coupling degree level, the spatial heterogeneity map of the coupling degree (Figure
Spatial differentiation of the urban human settlements system’s coupling degree in provincial capitals.
The wind velocity influences the distribution of pollutant concentration in the air, and the wind direction determines the transport direction of various pollutants in the air. The wind direction in China as a whole is the northwest in the winter and the southeast from the sea in the summer. Therefore, the humidity increases in the summer, which enhances the adsorption and sedimentation of water vapor and is accompanied by the presence of certain precipitation, and the effectiveness of leaching can significantly improve the urban air environment. The public green area also affects the dust on the ground. During the windy and dry seasons, the impact of the green area on the local air quality in cities should not be overlooked. Because of fewer green areas, the air quality in Northwest China and the Loess Plateau region was reduced by the impact of dust, which in turn affects the human settlements. The quality of human settlements in Urumqi is relatively low, which is close to that of the eastern cities with developed economic and dense population, such as Wuhan, Hefei, and Nanjing. All of this is due to the lack of green areas, the impact of meteorological, the dust throughout the year, and uncoordinated development between environmental protection and control funds while developing industry. Due to the good condition in meteorology and green area, the overall human settlements quality in the south is not much different from the first level to the third level. The fact that closed circulation appears easily in the basin and the temperature inversion in a mountainous area is longer than that in the flatland limits air diffusion ability and aggravates the pollution. As a result, the quality of human settlements in Chongqing shows a poor side due to the traffic, air pollution, economic development, and meteorology.
The degree of diffusion of air pollutants is influenced by the thickness of the inversion layer in winter and summer. The inversion layer in summer is relatively thin and low; the inversion temperature in winter comes frequently and the atmosphere is relatively stable. At the same time, the impact of human activities on air quality is not conducive to the diffusion and dilution of pollutants discharged. The overall air quality index was clearly high in winter and low in summer. During the heating period, the burning amount of coal increased sharply, and the discharge of fireworks led to a heavy atmospheric pollution and the decline of air quality in the north. A sharp increase in coal consumption during the heating season in the northern region, combined with the release of fireworks and firecrackers in the winter, has caused a heavy atmospheric pollution and reduced air quality. Affected by the strong El Niño phenomenon, the frequent occurrence of static weather and frequent discharge of pollutants during the heating season led to a repeated heavy air pollution from the north to Beijing, Tianjin, Hebei, and the surrounding areas. The impact on productions and lives is relatively large, resulting in a low state of the human settlements environment under such circumstances, according to the calculation results: the human settlements quality of some cities is in the fifth level, such as Beijing, Shijiazhuang, Tianjin, and Zhengzhou.
Dust caused by municipal construction traffic is increased; population growth leads to the increase of emissions from industry and motor vehicles year by year, and the consumption of energy and fuel also increase. The impact of the urban population on air quality is a positive effect; higher energy consumption and industrialization levels can lead to deterioration of air quality. Therefore, the unfavorable factors such as the speed of economic development in each city and the influence of the environmental system are very important to the quality of human settlements in a city.
In addition, in the developed cities like Beijing and Shenyang, various types of human activities are frequent and continuous. Increased demand for gas and oil leads to increased mining speed, energy consumption, and dust removal, which affects the urban environment and reduces the annual overall living quality. With the increasing awareness of environmental protection, government increases expenditure on energy-saving and environmental protection and more residents choose public transportation, which have improved the urban air quality. What is more, industrial restructuring, improvement of energy efficiency and green coverage, reducing energy consumption by various means, and formulation of governance laws can lead urban air quality to show a turnaround trend. As a complex system, the five systems of human settlements interact and coordinate with each other. The coupling degree in southern China is relatively high, which shows that the social environment and natural ecological environment have a significant driving effect on the coupling degree of regional human settlements. The regions with a lower coupling degree are mainly concentrated in the northeast and northwest of China. The industrialization and urbanization there develop too fast with corresponding lags in the construction of the infrastructure, ecological environment, and so on.
Based on other indexes of air quality and human settlements, this paper takes 30 major cities in China as an example; it introduces the evaluation index system and summarizes the spatial and temporal distribution of human settlements quality based on air quality and the evaluation of the coupling degree of human settlements system.
Firstly, according to the temporal characteristics of the human settlements quality, there is almost no difference in the first and third quarters of major cities in China and 16 cities above the average quality. In the second quarter, the quality is the best in the four quarters and there are 17 cities above the average quality. However, in the fourth quarter, there were significant differences among cities and the city in the fifth level showed up the worst quality of living. The assessment of urban human settlements quality based on the air quality index shows that the quality in terms of urban spatial distribution mainly in North China and Northeast China is low, while the quality of human settlements in most parts of the coast, South China, and Northwest China is high, which generally agrees with the single assessment of human settlements based on PM2.5, but some cities show differences.
Secondly, the average coupling degree of the five major systems of human settlements is 0.48, which is in the phase of antagonism. Under the assessment of the air quality of human settlements, the coupling degree of the five major cities in China is not high, which could be improved by industrial upgrading, environment protection, technological progress, and its own resilience. The development of urban depends not only on economic development but also on various factors, such as the interdependence, mutual restraint, and promotion, which forms an integrated system and jointly promotes the coordinated development of the five major systems. Cities should enhance the coupling degree to improve competitiveness.
Thirdly, in the future, a spatial difference in the coupling degree will focus on different time-space scales of specific regions in order to find the weak link among systems and reveal the rules and mechanism of interactions more comprehensively and systematically. In spite of the rapid development of urban governance measures and the raising education on protection of and the increase of green areas, severe air pollution is still concentrated in cities with a relatively fast economic growth in recent years, which needs to balance the internal relations among the systems. Prevention of pollution and protection of air quality need to consider a variety of factors in order to improve the quality of urban human settlements, and it also becomes one of the goals of building a better livable city.
Last but not least, based on the perspective of air quality, this paper analyzes various factors to explore the change of human settlements quality among the major cities in the four quarters in 2015. It explores the impact of air quality on the human settlements in order to construct and improve services in urban human settlements better. However, due to the difficulty in obtaining some data, the index system is not perfect. At the same time, it is not much comprehensive in terms of time and space. There are only four quarters without more detailed classification in time and only 30 cities in China in space. The range of evaluation is small. Urban human settlements is an issue that needs further study in the future.
The authors declare that there are no conflicts of interest regarding the publication of this paper.
Li Xueming and Jiaji Gao contributed equally to this work.
This work was funded by the National Natural Science Foundation of China (41671158)