In this article, we pursue the objective of empirically testing the extent to which changes in environmental policy outputs can explain changes in environmental impacts. Previously, systematic testing of this relationship was hampered by the lack of a compelling measurement of changes in regulatory policy outputs. To remedy this, we present a novel approach to the measurement of events of regulatory output change. We illustrate our concept by employing data on changes in clean air regulations in 24 advanced democracies from 1976 to 2003. In a next step, we explore the extent to which changes in clean air regulations can account for changes in air pollutant emissions. The empirical analysis suggests that changes in clean air regulations cannot be unconditionally associated with changing intensities of air pollutant emission. We deem these results to have far-reaching implications for the study of regulatory policy change.
