Abstract
Considerable interest has focused on the possible existence of an environmental Kuznets curve whereby pollution first increases but later falls with increasing income. Empirical studies have concentrated on a wide spectrum of countries and run into inevitable problems of data quality and comparability. We avoid these problems by looking across the 50 U.S. states and find four major classes of air pollutants which decrease with increasing per capita income. Additionally, we look at the best measured of these pollutants, air toxics, for the period 1988-1992 and again find that an increase in income is associated with a decrease in per capita emissions. Considering the starting conditions in this case, however, reveals a more subtle relationship.