Christian Science Monitor: Mexico City was once known for its smoggy landscape with industrial eyesores such as the 18 de Marzo Refinery spewing ozone-forming emissions such as sulfur dioxide. The cloud of contaminants hanging over the capital played into an apocalyptic reputation for pollution, crime, and overpopulation; and it fueled urban myths, like the one about birds dropping dead mid-flight because of the poor air quality.
But the refinery named for the day Mexico expropriated its oil industry was ordered closed...