PNNL

Abstract

The world’s population is projected to increase 33% during the next three decades, to 8.1 billion. Nearly all of the projected growth is expected to be concentrated in urban centers. These rapidly expanding urban regions and surrounding suburban areas are leading to the phenomenon of megacities (metropolitan areas with populations exceeding 10 million inhabitants). Well governed, densely populated settlements can reduce the need for land conversion and provide proximity to infrastructure and services. However, many urban areas experience uncontrolled sprawl and their activities are the leading cause of environmental problems. These mega-centers of human population are tied directly to increasing demands for energy and associated industrial activities and motorization that lead to more emission of pollutants into the atmosphere. Air pollution is one of the most important environmental challenges of this century. This challenge is particularly acute in the developing world where the rapid growth of megacities is producing atmospheric pollution of unprecedented severity and extent. MILAGRO (Megacity Initiative: Local And Global Research Observations) is the first international collaborative project to examine the behavior and the export of atmospheric pollutants generated in megacities. The Mexico City Metropolitan Area (MCMA) - one of the world’s largest megacities and North America’s most populous city -- was selected as the initial case study to characterize the sources and processes of emissions from the urban center and to evaluate the regional and global impacts of the Mexico City air pollution plume