Emerging nations around the world are often heralded for their fast growth but we don't often hear about the downsides of that rapid development. The World Health Organization recently released a report on air quality in countries around the globe, on which we based� a list of the ten most polluted countries. Almost all the worst offenders are either major oil and gas producers, or emerging economies that are growing rapidly. The top ten most polluted countries have air quality levels from six times to 14 times the health risk level. Find out which countries in the world are the most polluted.