Asymmetric effects of economic policy uncertainty and environmental policy stringency on environmental quality: evidence from China and the United States.

The importance of economic policy uncertainty (EPU) and environmental policy stringency (EPS) in affecting environmental quality is gaining great attention in the literature. However, none of the existing studies has thought to investigate their combined effects on carbon dioxide (CO) emissions. Additionally, the individual investigations into the nexuses EPU-emissions and EPS-emissions primarily took a symmetric assumption between these variables into consideration. The current paper is an early attempt to close these gaps by examining the combined effects of economic policy uncertainty and environmental policy stringency on CO emissions within asymmetric (nonlinear) frameworks in China and the United States (US). The empirical findings indicate that an improvement in EPU degrades the environmental quality in both countries. However, a negative shift in EPU decreases emissions in China while increasing them in the US. In terms of EPS, the estimates in the two nations led to similar results. A positive change in EPS is conducive to fewer emissions, whereas a negative change worsens environmental damage. These findings still hold with the sensitivity analysis using ecological footprint as an alternative gauge of environmental destruction. This study, therefore, suggests that both nations adopt stricter environmental policies. Additionally, Chinese policymakers should work to lessen uncertainty shocks, while the US government should promote more transparent economic policies.