This position paper was commissioned by PETRA to look at the relationships between trade policies and air pollution. Regional trade agreements are increasingly including provisions to protect the environment. This paper looks at the scale, technique and composition effects of environmental impacts relating to trade liberalisation. Increased economic growth along with the transfer of environmental technologies and growth in environmentally-friendly goods are among the most positive effects. The negative impacts arise from pollution-generating activities being migrated to those countries that have less stringent environmental controls.