The environmental Kuznets curve (EKC) hypothesis, whereby pollution first increases then decreases as income increases along an inverted U-shaped path, has generated a large literature beginning in the 1990s. The current analysis contributes to that literature in two main ways, one theoretical and one empirical. First, the theoretical inquiry begins with the idea that a variety of societal parameters may significantly impact the trajectory of environmental quality. We show that changes to production and consumption elasticity can be used to identify the environmental impact of changes to any of these parameters. Special attention is devoted to the cases of income and population growth as each is widely recognized as commanding significant influence over environmental quality. We find that for a wide class of constant elasticity of substitution (CES) models (where production technology and consumer preferences are both in a CES form) both income and population growth lead to degradation of environmental quality along an inverted U-shaped path. This common feature is due to the fact that both income and population have the same relative impact (in their unbounded limits) on production and consumption elasticity. Second, a large new dataset for 1789 sites over 38 years is assembled making it possible to overcome data shortcomings in earlier studies. When integrating the theoretical insights for population change into the empirical model formulation, our results find robust inverted U-shaped relationships for air pollutants with rising incomes and rising population density. These findings provide some added perspective on the claims and implications for the EKC literature and expectations about the possible decoupling of economic growth and environmental damages.

环境库兹涅茨曲线 (EKC) 假说认为，随着收入沿着倒 U 形路径增加，污染首先增加然后减少，该假说从 1990 年代开始产生了大量文献。当前的分析以两种主要方式为该文献做出贡献，一种是理论方式，一种是实证方式。首先，理论探究始于各种社会参数可能显着影响环境质量轨迹的想法。我们表明，生产和消费弹性的变化可用于识别任何这些参数变化对环境的影响。特别关注收入和人口增长的案例，因为每个案例都被广泛认为对环境质量具有重大影响。我们发现，对于范围广泛的恒定替代弹性 (CES) 模型（其中生产技术和消费者偏好均采用 CES 形式），收入和人口增长都会沿着倒 U 形路径导致环境质量下降。这一共同特征是由于收入和人口对生产和消费弹性具有相同的相对影响（在其无限限度内）。其次，汇集了超过 38 年的 1789 个站点的大型新数据集，从而有可能克服早期研究中的数据缺陷。当将人口变化的理论见解整合到实证模型制定中时，我们的结果发现空气污染物与收入增加和人口密度增加存在稳健的倒 U 形关系。