Environmental regulation, energy consumption structure, and industrial pollution emissions

China has become the world’s largest carbon emitter due to its high-investment, low-efficiency development model. It is urgent to reduce industrial pollution emissions. This study analyzes the impact of environmental regulation intensity and energy consumption structure on industrial SO2 pollution emissions by establishing a fixed-effect regression model based on panel data from 2009 to 2018 in China. The results show that the overall environmental regulation intensity in China has a significant negative effect on industrial pollution emissions. In other words, increasing the level of environmental regulation is conducive to reducing industrial pollution emissions. The proportion of coal consumption in the overall national energy consumption structure directly and positively correlated with the concentration of industrial pollution emissions. Due to the differences in economic development and industrial foundation, the pollution emissions effect shows significant heterogeneity in the eastern and western regions of China under the constraint of environmental regulation. Based on these conclusions, this article proposes policy recommendations from four aspects: (1) strengthen environmental regulation, and pay attention to optimize the form of environmental regulation. For example, in the West of China, the government can encourage enterprises to carry out technological innovation and develop green energy hubs by policy and financial support; (2)improve the energy consumption structure, such as encouraging green production; (3) promote industrial structure adjustment and upgrading, such as promoting the energy saving transformation of energy-intensive enterprises, developing green technologies, and reducing the carbon emissions of industrial industries; (4)improve the foreign investment access system and guiding foreign investment to invest in key environmental protection projects.


Introduction
Since the reform and opening up in 1978, China's economy has grown rapidly, becoming the world's largest exporter and the second-largest economy globally.However, China's total energy production and consumption have also surged to the second place globally.The country's economy has long been growing in a high-input, high-consumption, high-emission, non-coordinated, non-recyclable, and low-efficiency way, which has put enormous pressure on the ecological environment.Economic development cannot be separated from energy consumption, and the energy consumption structure of our country has been dominated by coal and oil for a long time, as it shows in figure 1, Coal, petroleum and other fossil fuels account for more than 80% of energy consumption, while the consumption of natural gas, electricity and other clean energy is relatively low, and the consumption of energy will cause a lot of air pollution emission.The industrial energy consumption accounts for about 70% of the total energy consumption.
From the perspective of the total emissions of industrial air pollutants, the emissions of industrial SO 2 and NO x are much higher than the emissions of PM2.5, and the overall emissions show a downward trend, and the emissions of SO 2 show a trend of 'first reduce and then increase and finally decline'(figure 3).After 2011, emissions showed a rapid downward trend, and in 2015, they decreased by 21.5% compared with 2011.This is because there was no clear NOx emission policy and target before 2010.In 2011 and after, NOx emission reduction was clear and the denitration units installed in power plants and industrial boilers effectively reduce NOx emissions.
The report of the 20th National Congress of the Communist Party of China in 2022 points out that we need to work together to reduce carbon emissions, control pollution, expand greenery, and promote ecoprioritization, resource conservation and intensification, and green and low-carbon development.The 'Made in China 2025' 4 clearly stated that we need to curb industrial pollution and achieve green manufacturing and development.Therefore, reducing industrial pollution emissions and transforming the energy consumption structure is an urgent and important issue that needs to be solved.The study of the above issues has important theoretical and practical significance for promoting China's ecological civilization construction and achieving high-quality economic development.
2. Literature review 2.1.Relationship between environmental regulation and industrial pollution emissions Porter et al [1] proposed that reasonable environmental regulations would force enterprises to innovate in technology, offsetting the environmental cost of combating pollution from a technological innovation perspective.A significant amount of research has been conducted regarding the 'Porter Hypothesis.'For instance, Wagner [2] found that government environmental regulations and promoting green technological innovation can reduce environmental pollution.Lanjouw and Mody [3] provided evidence using Japan, the United States, and Germany as case studies to demonstrate a positive correlation between the number of environmental patents and environmental costs.Berman and Bui [4] confirmed that the productivity of the petroleum refining industry increases with stricter air quality regulations.Taking Japan as a starting point, Hamamoto [5] discovered that the enhancement of environmental requirements promotes companies' research and development (R&D) investment.Hettige's [6] research indicates a noticeable decrease in industrial pollution emissions in countries or regions with stringent environmental regulations.The studies conducted by Laplante [7] in the pulp and paper industry in Canada found that the implementation of government environmental regulations can significantly reduce pollutant emissions by businesses.Greenstone [8] and Kuang et al [9] proposed that different types of environmental regulations have different impacts based on data on haze pollution in central and western China, and suggested that optimizing and upgrading the industrial structure and improving technological levels will help mitigate pollution.
Chen et al [10] estimated the impact of foreign direct investment (FDI) on economic development under the influence of environmental regulations in 30 provinces in China.They found that environmental regulations significantly constrain FDI and China's economic growth but have a relatively small impact due to inadequate execution.
However, there are also different perspectives on this matter.Many scholars argue that environmental regulations inevitably increase the burden and costs for businesses, thereby weakening their technological innovation capacity and competitiveness [11][12][13][14].Gollop and Roberts [15] analyzed 56 electric utility firms in the United States from 1973 to 1979 and found that raising environmental standards actually resulted in a decline in total factor productivity for electric utility companies.

Calculation of environmental regulation intensity
Since the intensity of environmental regulations cannot be directly observed or measured, and a universally recognized measuring method has not yet been established, researchers usually select different variables and adopt different methods for measurement from their respective perspectives.
Yan and Guo [16] measured the indicator of environmental regulations by using the ratio of investment in wastewater treatment to industrial wastewater discharge as the cost of pollution per unit of discharge.Shi and Wang [17] used the ratio of investment in industrial pollution treatment to industrial value-added as the environmental regulation variable in their empirical study.Gray [18] used the ratio of US fiscal budget spending on environmental and natural resource protection to industrial pollution emissions as an alternative indicator of environmental regulation.Pearce and Palmer [19] advocated measuring the intensity of regional environmental regulations by combining government pollution control investments with corporate pollution reduction expenditures.Zhang and Zhao [20] used the industrial wastewater discharge compliance rate and the industrial SO 2 removal rate to indicate the intensity of environmental regulations.Based on micro-level data from over 30,000 newly established polluting enterprises, Wu et al [21] constructed an environmental dataset to examine the reduction rates of total emissions of two types of pollutants, SO2 and COD, as indicators of environmental regulatory intensity.
Some methods for calculating environmental regulation indicators are too complex.To avoid the complexity of the calculation, some studies use alternative indicators, such as per capita income levels, laws and 4 Regarding the 'Made in China 2025', it is a strategic document issued by the State Council of China in May 2015 to comprehensively promote the implementation of the manufacturing power strategy, and is the action plan for the first decade of China's implementation of the manufacturing power strategy.This document is the top-level plan and roadmap for the next 10 years of China's manufacturing industry.Through efforts to achieve three major transformations: China's manufacturing to China's creation, China's speed to China's quality, and China's products to China's brand, China will basically achieve industrialization by 2025 and enter the ranks of manufacturing powers.
regulations related to environmental protection, or the number of administrative penalty cases related to environmental issues.Damania et al [22] showed that the level of lead in gasoline is strongly related to the level of environmental regulation.Higher levels of lead indicate a lower level of environmental regulation in that area.In addition, per capita GDP is also one of the alternative indicators.

Relevant research on the impact of environmental regulations on energy consumption structure
Shi et al [23] analyzed panel data on China's environmental regulation intensity and energy consumption structure from 1998 to 2006, and found a significant negative correlation between coal consumption and environmental regulation intensity in energy consumption structure.Building upon the research of Antras and Zhai et al [24,25], Lin et al [26] used the Markov chain process to simulate and predict that if China adopts strict environmental regulations in the future, the proportion of one-time energy consumption such as coal in 2030 will decrease to around 47%.However, if there is no corresponding supply of other energy sources or insufficient supply of other energy sources, it will be difficult for the proportion of coal to decrease due to the increase in environmental regulation intensity.Soytas [27] investigated the effect of energy consumption and output on carbon emissions in the United States.In the long run, energy consumption will affect carbon emissions.Stern [28] analyzed the impact of energy consumption structure on the environment, emphasizing the role of energy consumption structure in improving environmental conditions.Some scholars have also discussed the influence of total energy consumption on China's environmental quality (Poon et al [29], Wang and Feng [30]).Furthermore, researchers have examined the environmental effects of replacing coal with clean energy such as solar energy, wind energy, ocean energy, and bio-energy, and adjusting energy consumption structure (Amundsen et al [31], Lindmark [32], Grossman and Krueger 1995 [33]).
The above literature provides research ideas and empirical evidence for this article, but current research mainly focuses on exploring the relationship between environmental regulations and industrial pollution.There is less research on the impact of environmental regulations and energy consumption structure on industrial pollution emissions.In fact, the energy consumption structure is a powerful intermediary between environmental regulation and pollution output, So it is very necessary to combine the three.The marginal contributions of this article are as follows: First, the green economy has developed rapidly in recent decades, and it is closely related to industrial pollution emissions and energy consumption.It is necessary to analyze the three in a unified framework.This article analyzes in-depth the impact of environmental regulations and energy consumption structure on industrial pollution emissions, enriching the research perspective of existing literature.
Second, this article reveals the mechanism of environmental regulations promoting the energy consumption structure from three aspects and uses a combination of mediating effect and spatial econometric analysis to depict the emission reduction effect of environmental regulations, making the research results more reasonable.
Third, considering the significant differences in economic development and industrial foundation between the eastern and western regions of China, this article discusses the heterogeneous impact of different environmental regulation tools on industrial pollution emissions, providing new ideas for ecological governance in these regions.

Theoretical mechanism
3.1.Mediating effect analysis of the impact of environmental regulations on energy consumption structure 3.1.1.Mediating effect of technological innovation Environmental regulation affects energy consumption structure through technological innovation.Environmental regulations not only have a positive 'innovation compensation' effect, that is, by indirectly forcing companies to engage in technological innovation to reduce energy consumption, but also have negative 'compliance cost' and 'rebound effects'.Under the influence of government environmental regulations, companies have to increase investment in energy-saving and emission-reduction in order to meet regulatory goals, which will increase their production costs for a period of time.In addition, increasing investment in energy-saving and emission-reduction may 'crowd out' investments in other aspects of the company, leading to a reduction in productive investments and affecting the improvement of company productivity, and even causing inefficient production.However, in the long run, if the government can implement reasonable environmental regulations, it can encourage companies' technological innovation capabilities, improve their product competitiveness, and thus offset the loss of productivity caused by the impact of environmental regulations and even generate surplus.This not only promotes technological innovation but also reduces pollution emissions and improves the environment.However, technological innovation may also generate a 'rebound effect'.On the one hand, technological innovation can accelerate the speed of economic growth, but the faster the economic growth, the more energy consumption is needed.On the other hand, the emergence of new technologies after technological innovation will make energy extraction easier.The prices of fossil fuels such as coal and oil will relatively decrease, resulting in a reduction in companies' investment in energy purchasing, but also increasing additional energy demand and consumption.In general, whether the 'follow the cost' effect dominates or the 'innovation compensation' effect dominates will affect the direction of the impact of environmental regulations on energy consumption.

The intermediary effect of industrial restructuring
Environmental regulation affects the structure of energy consumption by affecting the adjustment of industrial structure.Strict environmental regulations will force enterprises with high pollution emissions to abandon industries with high pollution emissions and opt for new green and clean environmental industries such as technological innovation to effectively reduce their environmental pollution costs.Some companies may simply set up high-energy-consuming and high-polluting enterprises in areas with lower levels of environmental regulation.Therefore, the reasonable formulation and effective implementation of environmental regulations can help local high-pollution and high-energy-consuming enterprises to transform, thus changing the local energy consumption structure and reducing energy consumption.However, for regions that are rich in resources and have long been highly dependent on resource-based industries for economic development, strict environmental regulations may not be able to optimize the industrial structure in the short term and may even increase the 'follow the cost' effect of environmental regulations.Research by some scholars has shown that achieving 30%-40% energy-saving through technological progress is feasible, while 60%-70% needs to be achieved by adjusting the industrial structure by reducing the proportion of high-energy-consuming industries and industries that consume fossil fuels in industry.Therefore, the impact of environmental regulations on energy consumption is uncertain and may vary with the degree of rationalization of the regional industrial structure, further empirical testing is needed.

The intermediary effect of foreign direct investment
Environmental regulation affects foreign investment and energy consumption structure.In today's economic globalization, a considerable number of countries in the world, including China, will reasonably use foreign investment to develop their own economies.The inflow of foreign investment generally has a driving effect on the local economic development level.In addition, foreign investment can improve the local level of technological development and bring advanced technological knowledge to the locality.However, in China, the performance evaluation is based on the local GDP, and in order to achieve better performance, phenomena such as 'developmental thirst' and 'political championship' exist in local governments in some areas.'Political championship' refers to the phenomenon of 'bottom-up competition' and 'non-complete implementation' caused by attracting foreign investment, which will lead to the powerlessness and disorder of environmental regulation and is prone to cause large resource consumption.The entry of foreign-funded enterprises with high pollution emissions makes it easy for the inflow area to fall into an environmental pollution quagmire and become a 'refuge' for resource-consuming and pollution-intensive enterprises in developed countries.If environmental regulation standards become more stringent, they can attract foreign capital with high quality, high technology, and low pollution.It will also bring leading scientific and technological advances and management methods to the location.The economic and management level of the region can be improved in all aspects.At the same time, foreign investment can also enhance the local region's technological innovation capability and spillover effects, achieving a balance between environmental regulation and economic development.In summary, from the perspective of the intermediary effect, foreign direct investment is a typical 'double-edged sword'.It can either have a beneficial or completely opposite effect on the economic and environmental conditions of the host country.When foreign direct investment changes, the impact of environmental regulations on energy consumption will also change(see figure 4).

Theoretical analysis of factors affecting industrial pollution emissions
The rationality of industrial pollution emissions is an important factor in determining the harmony of the environment, and maintaining a high level of environmental quality is also complementary to economic development.Many scholars have used cross-sectional data, time series, and panel data on environmental quality and economic growth in various countries (regions, cities) to conduct a large number of empirical tests on the Environmental Kuznets Curve, in order to conduct in-depth research on the relationship between environmental quality and economic growth.Eventually, it was found that the level of environmental quality does not determine the level of economic development, and the EKc curve depicts long-term changes and is related to multiple factors.Scholars have sought to summarize some factors that may affect environmental quality, such as population density, industrial structure, technological level, trade openness, environmental policy, etc, in order to deepen the analysis of the relationship between environmental quality and economic growth.
The factors influencing industrial pollution emissions are fairly complex, and the EKc curve depicts longterm changes.Moreover, as the environmental situation continues to deteriorate, it is unrealistic to simply rely on waiting for the turning point of the Kuznets Curve while developing the economy.The solution lies in improving the current status of environmental pollution while ensuring economic development.It is also important to explore the relationship between factors beyond industrial pollution and economic growth, such as natural factors, artificial factors, and environmental policies.

Model construction 4.1. Data description and sources
As for the variable of environmental regulation intensity, at present, scholars at home and abroad mainly measure environmental regulation from the following perspectives: first, investigate the intensity of environmental regulation from the perspective of environmental regulation policy; Second, it is measured by the proportion of pollution control investment in the total cost or output value of the enterprise (Berman and Bui [4]; Lanoie et al [34], Zhang Cheng [35], Third, it is measured by the operation cost of pollution control facilities (Zhaohong [36]), Fourth, the level of per capita income is used as an indicator to measure the intensity of endogenous environmental regulation (Antweiler et al [37], Luyang [38]), The above indicators for measuring the intensity of environmental regulation are insufficient to some extent.Based on the consideration of the relative perfection of the indicators and the availability of data, the second method is adopted for the intensity of environmental regulation in this paper.The environmental pollution control investment per unit of output in each province represents the stringency of environmental regulations.The environmental pollution control investment in each region comes from the 'China Environmental Statistics Yearbook' from 2009-2018, and the output in each region comes from the 'China Statistical Yearbook' from 2009-2018.
Regarding the variable of energy consumption structure, this paper draws on the method used by Liu [39], where the energy consumption structure is represented by the proportion of coal consumption in standard coal in the total energy consumption in each province (city, district).The physical quantity of coal consumption and the total energy consumption come from the 'China Energy Statistics Yearbook' from 2009-2018, and the coalto-standard coal conversion coefficient comes from the 'China Energy Statistics Yearbook' from 2017.Industrial pollution emissions are represented by the industrial SO2 emissions in each region, which come from the 'China Environmental Statistics Yearbook' from 2009-2018.
As environmental regulations can reduce or increase energy consumption through indirect transmission mechanisms by affecting technological innovation, industrial structural adjustment, and foreign direct investment, in order to eliminate the influence of other factors and make the results more scientific, this study uses technological innovation, the proportion of the secondary industry, foreign direct investment, and the proportion of university enrollment as control variables(see table 1).(2) The proportion of the secondary industry is represented by the ratio of the added value of the secondary industry to the GDP in each region from 2009-2018.Data sources are the statistics bureaus in each province.(3) Foreign direct investment is represented by the ratio of foreign direct investment to GDP in each region of China from 2009-2018, with data source from the 'China Statistical Yearbook'.
(4) The proportion of university enrollment is represented by the ratio of the number of university students to the population in each region of China from 2009-2018, with data source from the National Bureau of Statistics.

Model specification in econometrics
To explore the relationship among environmental regulation intensity, energy consumption structure and Industrial pollution emissions, the following econometric model is established: Taking the natural logarithm of the equation above, the result is as follows: Where a = ( ) A ln 0 0 is the constant term; the subscript i represents the i-th province (city, district); t represents the year; IPD is the average annual industrial pollution emissions; ER is the environmental regulation intensity; ES is the energy consumption structure; all variables are natural logarithms; CV it is the set of control variables; coefficients a 1 and a 2 are the elasticity coefficients of environmental regulation intensity and energy consumption structure on industrial pollution emissions, respectively; e it is the random error term (see table 2).Table 2 shows the descriptive statistics of the explanatory variables, in which the mean value represents the mean of 290 cities or regions, such as 3.677, that the mean emission of industrial SO 2 in 290 regions in China is 36,7700 tons; 0.183 means that the average ratio of standard coal consumption to total energy consumption in the 290 regions in China is 0.183.

Panel fixed effects regression
Taking industrial pollution emissions as the dependent variable, environmental regulation intensity and energy consumption structure as the core explanatory variables, a fixed-effects panel regression was performed on the panel data from various regions from 2009 to 2018 [40].The regression results are as follows (see table 3): In order to visualize the results of regression analysis, we drew a forest plot (see figure 5).The forest plot directly reflects the correlation between variables.
From the regression results at the national level and the forest plot, it can be seen that there is a significant negative correlation between environmental regulation intensity and industrial pollution emissions in various The ratio of the provincial standard coal consumption to the total energy consumption Industrial pollution emissions(IPD) Industrial SO 2 emissions from each region Technology innovation(TEC) The proportion of R&D expenditure in regional GDP Industrial structure(IND) The proportion of the added value of the secondary industry in the regional GDP Foreign direct investment(FDI) The proportion of foreign direct investment in the regional GDP The proportion of university enrollment(PSC) The ratio of the number of students in the school to the number of students in the region regions.This suggests that the increase of environmental regulation intensity will reduce the industrial pollution emissions in China.
There is a significant directly and positively correlation between energy consumption structure and environmental pollution level.Both at the national level and in the overall energy consumption structure, the proportion of coal consumption is positively correlated with industrial pollution emissions concentration, indicating that an increase in the proportion of coal consumption will contribute to the rise of industrial pollution emissions.
Looking at the control variables, the industrial structure (IND) is positively correlated with the overall industrial pollution emissions in the country, indicating that the adjustment of industrial structure, such as reducing the proportion of the secondary industry including mining, manufacturing, electricity and gas, can optimize regional resource allocation, promote the coordinated development of regional industries, and improve environmental quality.Foreign direct investment (FDI) is negatively correlated with industrial pollution emissions, which is because in the early stages of attracting foreign investment in China, most foreign investment was attracted by replacing technology with the domestic market.Foreign multinationals have long occupied the research and development and sales stages at both ends of the 'smiling curve', and transferred labor-intensive and resource-intensive processes with high pollution and high energy consumption to China for production.There is no significant correlation between industrial pollution emissions and technological innovation (TEC).This is because the direction of environmental regulation on the efficiency of enterprise technological innovation mainly depends on the comparison of the 'innovation compensation effect' and the 'innovation offset effect'.The 'innovation compensation effect' can ultimately reduce or offset the environmental costs imposed on enterprises by environmental regulations, which encourages enterprises to continuously enhance their innovation capabilities and improve their technological innovation efficiency.The proportion of students in higher education institutions is also not significantly correlated with the level of  The upper corner marks * * * , * * and * are significant at the 1%, 5% and 10% levels, respectively.industrial pollution emissions.This indicates that although China has expanded higher education in recent years and the proportion of students in higher education institutions has increased, China is still in the stage of a developing country, and the increase in the number of people who have received higher education cannot temporarily change the reality of China's high level of industrial pollution emissions, which needs to be reconsidered after a period of time.

Robustness test
To verify the robustness of the fixed effects panel regression results, the emissions of industrial wastewater were used to replace the emissions of industrial SO2 in the value of the explained variable of industrial pollution emissions, and the technological innovation that was originally not significant in the control variables was replaced with the proportion of annual pollution fees to annual output value for each province.The data was obtained from the 'Environmental Statistical Yearbook' of each province from 2009 to 2018, and the results are shown in tables 4 and 5.
From the above two tables, it can be seen that both the replacement of the explained variable and the control variable are similar to the original regression results, indicating that the original regression results are robust.When replacing the emissions of industrial SO2 with the emissions of industrial wastewater, it can be found that technological innovation is more significant than industrial SO2 in regression analysis, while foreign direct investment is not significant.This suggests that technological innovation has a stronger impact on the emissions of industrial wastewater, while the impact of foreign direct investment on the emissions of industrial wastewater is relatively weak.

Heterogeneity analysis
Considering the significant differences in economic development and industrial foundation between the eastern and western regions of China, further exploration of the heterogeneous impacts of different environmental regulatory tools on industrial pollution emissions is conducted based on the overall analysis.Figure 6 shows the specific geographical distribution of China's eastern and western regions.Tables 6 and 7 respectively report the The upper corner marks *** , ** and * are significant at the 1%, 5% and 10% levels, respectively.The upper corner marks *** , ** and * are significant at the 1%, 5% and 10% levels, respectively.
impact of the same explanatory variables on industrial pollution emissions in the eastern and western regions.It is easy to find that in the eastern region, with a high level of marketization, a solid industrial foundation, and a faster economic development speed, the relationship between energy consumption structure, industrial structure, foreign direct investment, and industrial pollution emissions is more significant.
In the western region, except for the significant impact of environmental regulation intensity and foreign direct investment, the effects of explanatory and control variables such as energy consumption structure are weak.The reason is that the development of the western region is slower, started later, and has a weaker industrial foundation and lower population density.This indicates that improving the environment in the  The upper corner marks *** , ** and * are significant at 1%, 5% and 10%, respectively.The upper corner marks * * * , * * and * are significant at 1%, 5% and 10%, respectively.
western region should focus mainly on environmental regulation, while also promoting the coordinated development of reasonable resource allocation, a benign interaction between economy and ecology, and the improvement of regional infrastructure.In addition, it is noted that environmental regulation will affect the energy consumption structure through technological innovation, so the government can encourage enterprises to carry out technological innovation through policy and financial support, develop clean energy and drive economic growth with clean energy.For example, investing in green energy hubs in the west, to both bring the area up to the economic prosperity of the East, while also spreading the potential for unforeseen consequences of green energy between the East and West.This new investment in new technology seems a good way to 'spread economic prosperity' to the West, potentially distributing population more evenly as well.

Summary of the study
Based on the availability of data, this article uses panel data from various provinces (cities, districts) in China from 2009 to 2018 to analyze the impact of environmental regulation intensity and energy consumption structure on industrial pollution emissions.Through empirical analysis, the following main conclusions are drawn: (1) Overall, the environmental regulation intensity in China is inversely related to industrial pollution emissions.As the environmental regulation intensity increases, it can reduce the industrial pollution emissions in China.
(2) The proportion of coal consumption in energy consumption structure is directly related to the concentration of industrial pollution emissions.An increase in the proportion of coal consumption will increase the industrial pollution emissions.
(3) Industrial structure is significantly directly correlated with industrial pollution emissions.A decrease in the proportion of the secondary industry can reduce industrial pollution emissions.Therefore, adjusting the industrial structure can optimize regional resource allocation and improve the environmental level.
(4) Foreign direct investment is significantly negatively correlated with industrial pollution emissions.The long-term positioning of foreign multinational companies in the research and development and sales stages at both ends of the 'smile curve,' transfers the high-polluting and high-energy-consuming labor-intensive and resource-intensive stages to China, which aggravates China's industrial pollution emissions.

Countermeasures and suggestions
(1) The Chinese government should further improve the intensity of environmental regulation.We will improve relevant laws and policies on environmental protection and protect the ecological environment through legislative means.Although China has laws and regulations to prevent and manage industrial pollution, such as the Environmental Protection Law and the Prevention and Control Law of Air Pollution, the sound system of relevant laws and regulations still needs to be improved.For the sewage and waste discharge of enterprises exceeding the standard, the punishment should be increased to achieve the effect of reducing environmental pollution.However, it is important to keep in mind that the misunderstanding of blindly improving the intensity of environmental regulation should be formulated according to the actual characteristics of regions and industries (Poter [1]).In addition, the government should pay attention to optimizing the form of environmental regulation.The impact of a country's environmental regulation policy on its enterprises is not only related to the degree of tightness of environmental regulation measures, but also depends on the form of environmental regulation (Sartzetakis&constantatos, [41]).For example, the government encourages enterprises to produce green products by tax reduction or direct subsidies to reduce the emission of industrial pollutants; on the original tax system, expand the scope of high pollution and high energy consumption products and other taxes, establish carbon taxes to curb the production of high pollution and high energy consumption products, encourage green consumption to promote green production and green consumption, and protect the development of new energy and green industry.
(2) We will improve the energy consumption mix, reduce coal consumption, and develop clean energy sources.Clean energy represented by hydropower, wind energy, solar energy and biomass energy is safe and harmless renewable energy(Amundsen et al [42]).The government can encourage enterprises to make technological innovation through policy and financial support, and promote clean energy such as hydropower and wind energy to reduce the cost of clean energy and increase the utilization rate of clean energy to reduce excessive pollution emission.
(3) We will promote industrial restructuring and upgrading, and accelerate the pace of green transformation of China's high-end industry.As the 'world factory' and a major manufacturing country, China's industrial industry is not only a major traditional energy user, but also the main field of carbon dioxide emissions in China, accounting for about 80% of the country's total emissions.Industrial emission reduction is the top priority of the goal of 'carbon peak and carbon neutral'.To achieve the goal of 'carbon peak and carbon neutrality', we should not only strictly control the new capacity of the traditional energy-intensive and heavy chemical industries and promote their energy-saving transformation, but also accelerate the development of emerging industries such as high-tech industries, advanced manufacturing and digital economy.We will accelerate the low-carbon transformation of traditional industries, vigorously develop a new green and lowcarbon economy, promote the adjustment and upgrading of industrial structure, reduce energy consumption and carbon emissions in industrial industries, and gradually realize the decoupling of economic growth from carbon emissions.
(4) Adhere to technological progress and improve regional energy efficiency.Encourage R&D investment, improve regional energy efficiency through cost savings and technological innovation, so as to reduce industrial pollution emissions (Lindmark [43]).For example, all regions should strengthen mechanism innovation and system innovation, tap the potential of energy-saving technology, and optimize resource investment.Moreover, more advanced and efficient mechanical equipment should be equipped, and the old equipment should be updated and iterated.
(5) We will improve the access system for foreign investment and guide foreign investment in key environmental protection projects.Formulate and improve the access standards for energy consumption, water consumption and land occupation of foreign-invested projects, implement the system of compulsory elimination of backward processes, technologies and equipment for foreign-invested enterprises according to law; strengthen the environmental protection supervision of various enterprises including foreigninvested enterprises, strengthen law enforcement, and implement cleaner production audit, environmental identification and environmental certification system.We will accelerate the development of the ecological environment in the central and western regions, and encourage foreign investment in biomass energy conversion and clean energy projects.

Figure 1 .
Figure 1.China's energy consumption structure and proportion of industrial energy consumption in 2005-2017.

Figure 2 .
Figure 2. China's main sources of air pollutant emissions from 2005 to 2015.

Figure 3 .
Figure 3. China's main sources of air pollutant emissions from 2005 to 2015.

( 1 )
The technology innovation index is represented by the intensity of scientific and technological funding in each region of China from 2009-2018, which is measured as the proportion of scientific and technological funding to GDP.Data sources include the 'China Science and Technology Statistics Yearbook' and the 'China Statistical Yearbook'.

Figure 4 .
Figure 4. Mediating effect mechanism of environmental regulation.

Figure 6 .
Figure 6.Map of east and west china.

Table 1 .
Variable selection and definition.

Table 2 .
Descriptive statistics for each explanatory variable.

Table 3 .
Panel fixed effects regression.