Norilsk, Moscow and St. Petersburg top the ranking of Russia's 100 most polluted cities, according to a list compiled by the RIA Rating agency based on data from the Federal Statistics Service. The northern mining city dominated the rating, emitting 1.9 billion tons of pollutants into the air last year...The rating measured emissions from cars and stationary objects, such as factories...Most of the cities that also made the ranking's top 10, such as Asbest and Magnitogorsk, have large metallurgical, oil and chemical facilities. Almost half of the cities in the top 20 have a million residents or more.