Does the Environmental Kuznets Curve Describe How Individual Countries Behave?

The environmental Kuznets curve (EKC), an inverted-U relationship between pollution and income, is an influential generalization about the way environmental quality changes as a country makes the transition from poverty to relative affluence. The EKC predicts that pollution will first increase, but subsequently decline if income growth proceeds far enough. We examine within-country time series data on air pollution and income for a sample of individual countries to see if this generalized prediction is commonly borne out. The empirical approach employs robust, nonparametric methods and a recently available data set on SO2, smoke, and particulate air pollution. In most cases examined, the within-country income-pollution patterns we observe do not differ significantly from what would be expected to occur by chance. Where income-pollution relationships are consistent with EKC predictions, the patterns involved are also consistent with a much simpler hypothesis.