The Global Monitoring Plan (GMP) under the Stockholm Convention on POPs is a tool that collects information on POPs in the environment and in humans. The GMP is a key component of the effectiveness evaluation of the convention and provides a harmonized framework to identify changes in concentrations of POPs over time, as well as information on their regional and global environmental transport. This report summarizes and assesses the results of POP concentration in air from the four regional UNEP/ Global Environment Facility (UNEP/GEF) GMP2 projects.