- freely available
Int. J. Environ. Res. Public Health 2019, 16(24), 4936; https://doi.org/10.3390/ijerph16244936
2. Literature Review
3. Methodology and Variables Selection
3.1.1. Exploratory Spatial Data Analysis
3.1.2. Spatial Econometric Model
3.2. Variables Selection and Indicator Description
- Urban scale (Us) is characterized by urban population size, measured by the total population at the end of each year in one city [37,39]. Excessive urban population size will bring more resource consumption, housing demand, and travel demand, which indirectly aggravates haze. Thus, Us is expected to be positive for haze pollution [54,55,56].
- Urban agglomeration (Ua) refers to urban economic agglomeration, which is represented by gross national product (GDP) at each year of one city. In the urbanization process, urban economic agglomeration is the result of the concentration of economic units and activities to cities, which will lead to the decline of air quality. Urban economic agglomeration includes industrial, capital, and labor agglomeration, which can be largely reflected by GDP of one city. Therefore, GDP is used to characterize the positive impact of urban economic agglomeration on haze pollution [15,37,51].
- Advanced industrial structure (Str) is obtained by concluding the ratio of the output value of the tertiary industry to the output value of the secondary industry in one city [13,58]. As an important indicator of energy conservation and pollutant emission reduction, it reflects the degree of transformation of industrial structure from labor and capital intensive to technology and knowledge intensive. It is known that the secondary industry is the main source of industrial waste and air pollution, while the tertiary industry (including information technology, financial service, etc.) could reduce the negative externalities of environmental pollution . Therefore, advanced industrial structure is chosen to reflect its negative impact on haze pollution.
- Scientific and technological level (Tec) is represented by the proportion of science and technology expenditure in the local financial budget to the GDP of the year [19,47]. To some extent, the improvement of scientific and technological level will inhibit the aggravation and diffusion of haze [13,14]. Therefore, Tec is expected to be negative for Pm.
- Foreign direct investment (FDI) is measured by the total amount of foreign direct investment actually utilized, which reflects the economic opening-up of one city [59,60]. After entering WTO in 2001, China has introduced large numbers of foreign investment to promote economic development. FDI brought not only many advanced production technologies, but also lots of polluting enterprises that directly lead to the deterioration of China’s air quality . Therefore, the effect of FDI on Pm remains controversial.
4.1. Spatiotemporal Distribution Analysis
4.2. Spatiotemporal Correlation Analysis
4.2.1. Global Spatiotemporal Correlation
4.2.2. Local Spatiotemporal Correlation
4.3. Spatial Effects Analysis
4.3.1. Model Estimation
4.3.2. Parameter Estimation Results
4.3.3. Spatial Effect Decomposition
6. Conclusions and Policy Implications
- In the 21st century, the spatial pattern of urban population size and economic agglomeration brought by China’s rapid urbanization has certain regional overlap with the distribution of haze. From 2001 to 2016, the spatial distribution patterns of urban scale, agglomeration, and haze in China all presented an asymmetric spatial distribution pattern of “high in the east and low in the west”, which was opposite to that of urban scale and agglomeration, with the center of Chinese urbanization having been moving southward. These regional overlap differences show that the distribution of haze is not only affected by urban scale and agglomeration, but also impacted by regional natural conditions, climate change, industrial structure, technological levels and so forth.
- The local spatial correlation of haze pollution with urban scale and agglomeration is more obvious on the scale of China’s urban agglomerations. The spatial distribution of haze pollution in Chinese cities is affected by the effect of urban agglomeration. The results of their univariate and bivariate Moran’s I show a significantly positive global spatial autocorrelation in China, with the levels of spatial dependence fluctuating upward. The local spatial correlation of haze pollution and urban scale and agglomeration was dominated by HH and LL types, the number of which increased continuously during 2001 to 2016. The cities of HH type were mainly distributed in Shandong Peninsula, Beijing-Tianjin-Hebei, Yangtze River Delta, and Chengyu urban agglomeration.
- Haze pollution in neighboring cities could interact with each other, and has significant spatial spillover effect with the coefficient of 0.416. At the same time, both urban scale and agglomeration have an important impact on haze pollution. The direct effect of urban scale on haze pollution is more prominent than that of urban agglomeration, while the indirect effect of urban agglomeration in neighboring cities is more obvious than that of urban scale in local city. Every 1% positive change of urban scale and agglomeration in Chinese cities will promote PM2.5 concentration to increase by 0.238% and 0.117%, respectively. However, the spatial interaction of urban scale and agglomeration among cities will indirectly lead haze to increase by 0.161% and 0.204% in neighboring cities.
- Decomposing the spatial effect of control variables (per capita GDP, advanced industrial structure, scientific and technological level, foreign direct investment) into direct and indirect effects, we found that the improvement of per capita GDP will increase haze pollution in both local and neighboring cities, while the improvement of advanced industrial structure and scientific and technological level will alleviate haze pollution in local city and neighboring cities, among which the determinant of advanced industrial structure is more prominent in reducing haze in local city, and the determinant of scientific and technological level is more obvious in reducing haze in neighboring cities. Foreign direct investment, which plays an important role in the rapid development of urbanization in China, has no clear relationship with haze pollution.
6.2. Policy Implications
- Nowadays, China should abandon the development mode of land- and economy-centered urbanization and choose the way forward for people- and environment-oriented urbanization. Inclusive growth and a green economy should be the government’s guiding principles in the future [51,54]. To support these principles, China needs to restructure its economic and industrial structure to reflect environmental externality, expand the use of market-based instruments to control air pollution, and carry out legal reforms to clarify responsibility of each interest subject and promote inter-enterprise and inter-governmental cooperation [66,67].
- The expansion of urban scale and economic development of Chinese cities has caused seriously negative impact on air quality that related to the physical and mental health of residents. Local governments must attach great importance to the urgent situation of haze control, strengthen the prevention and governance of haze pollution, and immediately take haze countermeasures of regional joint prevention and control, joint management among departments, and active participation of social forces to improve regional air quality .
- In the pursuit of population-scale economy, local governments should pay more attention to the improvement of personnel quality and improve the public’s awareness of environmental protection . Moreover, it will be wise and meaningful for local governments to consciously practice the idea of green development and advocate the use of clean energy in production and life. Only in this way can they reduce air pollution caused by the high concentration of population and realize the healthy and sustainable green development of these cities with highly concentrated populations .
- While pursuing high-speed economic growth, local governments should pay more attention to the upgrading and rationalization of industrial structure and promote the synchronous and balanced development of regional industry and environmental quality. Policy-makers of each city should continue to strengthen the optimization and upgrading of industrial structure according to its own economic development level and resource advantages . In addition, much attention should be paid to the improvement of investment structure, especially the investment structure of science and technology, and advocate the development of green GDP . The efficiency of energy and resource utilization in the production activities of enterprises should also be improved to achieve energy conservation and emission reduction, and offset the environmental pressure brought by the improvement of industrial agglomeration.
Conflicts of Interest
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|Variables Type||Variable Full Name (Unit)||Abbreviation||Mean||Standard Deviation||Data Sources|
|Dependent variable||Particulate Matter (PM2.5) concentration (μg/m3)||Pm||0.81||1.02||SEDAC|
|Core independent variables||Urban scale (ten thousands)||Us||5.62||8.95||CCYS, CSYR|
|Urban agglomeration (ten thousands)||Ua||3.22||5.60||CCYS|
|Control variables||Per capita GDP (yuan)||Pgdp||4.55||3.20||CCYS, CSYR|
|Advanced industrial structure (%)||Str||0.23||0.09||CCYS|
|λ Scientific and technological level (%)||Tec||0.18||0.07||CCYS, CSYR|
|Foreign direct investment (ten thousands)||FDI||6.35||2.15||CCYS|
|lnUa||0.124 * |
|W *lnUa||0.112 *|
|W *lnPgdp||0.103 **|
|W *lnStr||−0.076 **|
|W *lnTec||−0.110 *|
|W *lnFDI||0.108 **|
|Direct effect||0.238 *||0.117 ***||0.086 *||−0.105 *||−0.081 *||0.156|
|Indirect effect||0.161 **||0.204 *||0.020 **||−0.093 *||−0.101 **||0.101|
|Total effect||0.399 *||0.321 **||0.106 *||−0.198 **||−0.182 **||0.257|
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