Sample distribution by industry.

The main objective of this paper is to study the impact of the Ambient Air Quality Standard (2012) on the green innovation of Chinese firms in polluting industries. The analysis features “leverage effect” of Porter Hypothesis imposed by environmental regulations and exploits exogenous variations caused by the promulgation of the new policy. Based on the exogenous variations, this paper uses the time varying PSM-DID method. The findings of this study suggest that the implementation of the new policy improves firms’ green innovation. Increments in R&D investment and environmental protection investment are channels through which the new standard positively affects firms’ green innovation. The cross-sectional heterogeneity analysis exhibits that the effect of this environmental regulation is stronger for firms with bigger size and lower financial constraints. The contribution and significance of this study are as follows: our study enriches understanding of the impact of environmental regulation on firms’ green innovation by empirically confirming the influencing channels of the impact of environmental regulations on green innovation. In addition, this paper contributes to the firms’ green innovation literature by empirically validating the role of corporate characteristics in moderating the effect of environmental regulations.

本研究旨在探究《环境空气质量标准（2012）》（Ambient Air Quality Standard (2012)）对中国污染行业内企业绿色创新的影响。本研究以环境规制下波特假说（Porter Hypothesis）的“杠杆效应”为分析逻辑，借助新政策颁布所引致的外生政策变动作为准自然实验场景，并基于该外生冲击采用时变倾向得分匹配-双重差分法（time varying PSM-DID）开展实证分析。

研究结果表明，该项新政策的实施显著提升了企业的绿色创新水平。研发（Research and Development，R&D）投入与环保投入的增加，是该项新标准正向影响企业绿色创新的核心传导渠道。横截面异质性分析结果显示，相较于规模较小、融资约束较高的企业，该项环境规制对规模更大、融资约束更低的企业的绿色创新促进效应更为显著。

本研究的贡献与意义如下：其一，本文通过实证验证了环境规制影响企业绿色创新的具体传导路径，深化了学界对环境规制与企业绿色创新之间作用机制的认知，丰富了相关研究成果；其二，本文通过实证检验证实了企业异质性特征在调节环境规制效果中的作用，为企业绿色创新领域的学术研究提供了新的经验证据，进一步拓展了该领域的研究文献。