Economic Growth and the Environment
考察人均收入与多种环境指标之间的简化关系，发现经济增长初期环境恶化，随后改善，转折点大多在人均收入8000美元之前。
We examine the reduced-form relationship between per capita income and various environmental indicators. Our study covers four types of indicators: urban air pollution, the state of the oxygen regime in river basins, fecal contamination of river basins, and contamination of river basins by heavy metals. We find no evidence that environmental quality deteriorates steadily with economic growth. Rather, for most indicators, economic growth brings an initial phase of deterioration followed by a subsequent phase of improvement. The turning points for the different pollutants vary, but in most cases they come before a country reaches a per capita income of $8000.