Does the environmental kuznets curve describe how individual countries behave?

We examine within-country time series data on income and concentrations of SO2, smoke, and particulates to see if the shapes of pollution-income relationships in individual countries agree qualitatively with predictions of the environmental Kuznets curve. The shapes of these relationships are determined non-parametrically for individual countries using recently available data on air pollution concentrations. For smoke and particulates, the shapes of within-country, pollution-income patterns do not agree with the EKC hypothesis more often than chance would dictate. For SO2, which generally exhibits EKC-consistent pollution-income relationships among wealthier countries, the observed patterns are also consistent with a simpler hypothesis.