## 5 Conclusions and Suggestions on Policies  
Based on the above analysis, this paper discloses that weak and strong atmospheric self-purification capacities determine the degree of atmospheric (environmental) pollution in Hebei and Guangdong, two provinces with many pollution-intensive industries. Specifically, this paper comes to the conclusion at three levels. First, atmospheric self-purification capacity has a significant inhibitory effect on environmental pollution. There is a significant negative correlation between (local) atmospheric self-purification capacity and environmental pollution. The absolute values of the coefficients of the total effect and direct effect of atmospheric self-purification capacity reach \(1.553\) and \(1.337\), respectively. Second, atmospheric self-purification capacity has a spatial spillover effect. Atmospheric self-purification capacity forms a negative correlation with the environmental pollution in neighboring regions, yet the effect proves insignificant. The absolute value of the coefficient of the indirect effect of atmospheric self-purification capacity reaches \(0.216\). Third, there is a threshold effect in the impact of atmospheric self-purification capacity on environmental pollution. With environmental regulation as a threshold variable, the threshold value reaches \(11.6349\). When environmental regulation reaches lower than \(11.6349\), the regression coefficient of environmental regulation to environmental pollution proves significant and reaches \(-0.080\). When environmental regulation reaches higher than \(11.6349\), the regression coefficient of environmental regulation to environmental pollution proves significant and reaches \(-0.065\). To conclude, a high degree of regional environmental regulation attenuates the inhibitory effect of atmospheric self-purification capacity on environmental pollution. In line with the research conclusion, this paper proposes suggestions for policies as follows. First, relevant parties should scientifically facilitate atmospheric self-purification capacity, especially in heavily polluted regions. Atmospheric self-purification capacity effectively curbs regional environmental pollution. Local governments should make full use of environmental self-purification capacity to improve air quality. Atmospheric self-purification capacity is affected by both natural factors and human factors. Natural factors lack elasticity. Seasonal change, terrain condition, atmospheric stability, maximum mixed-layer thickness, and other factors seldom change significantly. Therefore, by changing human factors (e.g., the ratio of built-up area, urban green planning, and reasonable industrial layout), relevant parties can form targeted strategies to improve regional atmospheric self-purification capacity. While planning energy structure, industrial development and urban-construction layout in a coordinated way, governments can comprehensively take technological measures to prevent and control pollution, and control the total emission and concentration of pollutants within the scope of environmental bearing capacity. Second, relevant parties should reasonably formulate environmental policies in heavily polluted regions and give full play to the inhibitory effect of atmospheric self-purification capacity on environmental pollution. Atmospheric self-purification capacity has a significant threshold effect on environmental pollution. In other words, when the degree of regional environmental regulation remains relatively high, the inhibitory effect of atmospheric self-purification capacity on environmental pollution will be restricted. Local governments should take high-quality economic development as a guideline and lay down reasonable policies on environmental protection on the basis of promoting atmospheric self-purification capacity.