China has become the largest economic body in Asia and the second largest in the world after 40 years of rapid economic growth since the implementation of the reform and opening up policy. The average annual growth rate of China’s gross domestic product reached 12% from 1978 to 2017. China also has the highest fossil energy consumption and is one of the countries with the highest pollution emissions [
1]. The emissions of pollutants, such as sulfur dioxide, nitrogen oxides and particulates, are present at a high level in China. China has become one of the most polluted regions in the world [
2] and the past 40 years of economic growth have incurred a high cost of environmental pollution. As the two major engines of rapid economic growth, industrialization and urbanization are considered the major reasons for environmental pollution. Urban development has benefited from the rapid growth of industrialization and urbanization has also provided numerous production factors for industrialization. The two engines interact and enhance each other. However, pollutant emissions from industrialization have also made urban regions the most polluted geospatial units.
The Chinese government has implemented various policies and measures to reduce pollutant emissions and to alleviate urban environmental pollution. A reduction of pollutant emissions has been set as a goal in five-year economic growth plans since earlier this century. For instance, the 11th Five-Year Plan proposed to reduce the emissions of sulfur dioxide by 9.96% by 2010 based on the amount of 25.49 million tons in 2005 [
3]. The 13th Five-Year Plan proposes to control total sulfur dioxide emissions to within 15.80million tons by 2020, a 15% decline from those in 2015 [
3]. To achieve these goals, the Chinese government has released rigorous environmental policies, primarily in three aspects: treatment at the end, management during the process and prevention at the source, such as pollution taxes (charges), emission rights trade and policies, to promote the development and use of clean production technologies. The emission reduction goals and the implementation of corresponding policies have transformed the industrial structure and production modes. For instance, the growth of the recycling economy has reduced the emission of traditional pollutants such as SO
2 and particulates and has alleviated urban environmental pollution to some extent. However, from the perspective of sustainable development, China still faces enormous environmental pressure. The pollution issue has not been effectively eradiated. More strict pollution treatment goals are still needed. For instance, the 13th Five-Year Plan proposed to reduce energy consumption by 15% per ten thousand yuan gross domestic product by 2020, as compared with 2015, and to control the total energy consumption to within 5 billion tons of standard coal. The total emissions of chemical oxygen demand, ammonia, sulfur dioxide and nitrogen oxide are proposed to be controlled to within 20.01 million, 2.07 million, 15.80 million and 15.74 million tons, which are declines of 10%, 10%, 15% and 15%, respectively, from 2015. In addition, the total emissions of volatile organic compounds are expected to decline by 10% from the 2015 value [
3]. Therefore, an investigation of paths between urban economic growth and pollutant emissions is imperative. This type of research will provide a reference for policy making to ultimately achieve a win-win situation for economic growth and environmental protection.
The relationship between economic growth and environmental pollution has been always a discussion topic in academia. One of the core themes is the environmental Kuznets curve (EKC) hypothesis. Scholars such as Grossman first discovered an inverted U-shaped relationship between economic growth and pollutant emissions—the EKC—that is, with economic growth, pollutant emissions tend to first increase (corresponding to environmental deterioration) and then decrease (corresponding to the improvement of environmental quality) [
4]. Subsequently, a large number of empirical studies have been conducted on the EKC and its shape. Two major environmental indicators have been applied in empirical studies. One is the pollutant emission amount. With the expected increase of environmental quality, the specific pollutants that empirical studies are concerned with have gradually expanded from the traditional sulfur dioxide [
5], nitrogen oxides [
6] and waste water [
7] to greenhouse gases [
8] and particulate matter 2.5 (PM2.5) [
9]. The other is comprehensive environmental pressure indicators, such as the ecological footprint [
10,
11] and ecological efficiency [
12,
13]. In addition, with the increase in resource pressure, scholars have started to pay attention to the empirical relationship between resource utilization and economic growth, mainly to test whether economic growth has an EKC empirical relationship to land utilization [
14], energy consumption [
15,
16], or water resource consumption [
17]. Current research indicates that the EKC hypothesis is only applicable to atmospheric pollutants, in particular, regional pollutants [
18]. The current empirical study results of global pollutants, greenhouse gases, comprehensive environmental pressure indicators, or energy consumption do not always support the EKC hypothesis [
19]. In fact, different research results have been derived for different pollutants [
20]. In addition, research results could be different when different quantitative methods are used [
21,
22]. Substantial empirical studies have been conducted to investigate the existence of EKC in China, such as those with provinces [
23,
24,
25,
26] or prefecture-level cities [
27] as spatial units, or those with particular regions as research subjects [
28,
29]. However, no consensus has been reached [
30]. Therefore, research on the relationship between economic growth and the environment should take into consideration the properties of particular pollutants [
19]. The “black box” of traditional empirical studies also needs to be broken to investigate the path through which economic growth affects environmental quality. Such research will help in the development of targeted policies to achieve continuous economic growth while improving the environmental quality.
In general, current research at national scale focused on the verification of EKC hypothesis in different regions and time periods. In terms of research methods, traditional methods such as single polynomial equations are mostly applied to estimate data [
31], which are not able to reveal the mechanism of the impact of economic growth on environmental pollution. A question is how economic growth directly or indirectly affects environmental pollution through industrial structure, technological innovations and environmental regulations. Few studies have been conducted in this regard. Therefore, using a structural equation model and 283 prefecture-level cities in China as a sample, we quantitatively analyzed the path and mechanism through which the economic growth of 2005 and 2015 directly or indirectly affected environmental pollution and we explored the structural causes of environmental pollution. We anticipate that our study will provide a reference for the development of targeted policies to achieve coordinated economic and environmental development.