Air pollution is rampant in Russia, where about 120 cities have noxious gases in the air at more than five times acceptable limits, according to the head of the nation’s ecology committee. In all, 61 million people living in 185 cities — more than one-third of Russians — breathe air with high noxious gas levels. The main sources of the air pollution are oil, chemical, and metallurgical factories. Moscow ranks as one of the most polluted cities in the nation.