The Dirty Little Pollution Secret That's Choking Mexico City

Millions of people in Mexico City are choking on the worst air quality in 14 years, as cars and trucks add to the pollution with their outdated emissions controls. And it’s not as though Mexico lacks access to the best technology.

The nation’s export-oriented factories, the focus of a $20 billion investment boom, ship motor vehicles to countries with strict pollution limits. Yet Mexico’s requirements are less stringent so cars, pickups and commercial trucks sold domestically don’t live up to the same emissions standards as the models made for foreign buyers.