1. Air Pollution in Mexico City

3. Why? Mexico City provides a unique and important location to study nanoparticle formation. Its distinctive geography (located 7,400 feet above sea level, the city is encircled by mountains that effectively trap pollutants), large human population (18 million), and significant number of cars (about 3.4 million) all contribute to making it among the world’s most polluted cities. Until recently, little information was available about the distribution and dynamics of nanoparticle formation in and around Mexico City. Seeking to gain a better understanding of how nanoparticles form in this region, a team of scientists from the National Center for Atmospheric Research (NCAR) and the University of Minnesota collected this information as part of the 2006 Megacity Initiative: Local and Global Research Observations (MILAGRO) field campaign.world’s most polluted citiesMILAGRO http://images.google.com/imgres?imgurl=http://www.ncar.ucar.edu/assets/images/cars_pollution.jpg&imgrefurl=http://www.ncar.ucar.edu/i ndex.php/ncar/articles/small_but_mighty_virus_sized_pollutants_affect_mexico_city&usg=__DMw_GIXJ9R4gXvbm- ZZiHDG1yoM=&h=432&w=650&sz=30&hl=en&start=15&tbnid=j0eJRAe4dK50FM:&tbnh=91&tbnw=137&prev=/images%3Fq%3DMexico %2Bcity%2Bpollution%26gbv%3D2%26hl%3Den%26safe%3Dactive