The overlapping generations model (OLG-model) analyzes emissions of an accumulative pollutant in a laissez-faire economy and an economy regulated through a government controlled license market. The government either takes the price on the license market as given or sells the licenses demanded at the Cournot price. The first type of regulation is called a ‘liberal environmental policy’, and the second type a ‘monopolistic environmental policy’. The forward looking temporary and the stationary equilibria as well as the pollution boundaries of the mechanisms are studied. If people can choose between laissez-faire and regulation (or between the liberal and the monopolistic environmental policy regime), then in general no steady state exists. Instead endogenous policy cycles can alternate between laissez-faire and regulation or between liberal and monopolistic regulation.