Coming up for air
Wednesday, October 29, 2014 - 05:30
in Earth & Climate
Sometimes you've got to hit bottom to battle your way back up. In 1992, the United Nations cited Mexico City as having the worst air quality in the world, with so much pollution that birds sometimes dropped dead in mid-flight. The sprawling megacity contained a swirl of pollutants, including lead, ozone, and particulates. Ozone alone contributed to 1,000 premature deaths a year and 35,000 hospitalizations.