Ten Most Polluted Places Named: La Oroya. Natgeo,Sept.19Two girls walk to school amid smoky skies in La Oroya, Peru, in this September 2003 photo. The congested mining town of 35,000 nestled high in the Andes was recently added to the Blacksmith Institute’s list of the ten most polluted places in the world. A metal smelter run by the Missouri-based Doe Run Corporation has operated in the remote settlement since 1922. [See]. See more images in same page. See previous related new. See another related new: PERU: Gasping for Clean Air in La Oroya. See also video: Toxic Lead Smelting Operation in La Oroya, Peru