Mexico City a Living Laboratory for Smog Study

What's not in question is its attraction for the hundreds of atmospheric scientists who are wrapping up a monthlong study of the reach and repercussions of Mexico City's pollution: Where does it go? What does it become? What is its effect on climate and weather?

The answers could prove useful in cleaning up the air in other smog capitals, such as Cairo, Beijing, New Delhi and Los Angeles.

"We don't want to say that Mexico City is polluting the whole world," said Eric Hintsa of the National Science Foundation, one of the sponsors of the $25-million study. "But together, all the mega-cities are having an impact."

Picking Mexico City was a no-brainer, scientists say. The air here stinks.

Like a giant San Fernando Valley, Mexico City is surrounded by mountains. This valley, though, is 7,000 feet closer to the sun -- better to cook the effluence of an estimated 9 million vehicles, oil refineries, a volcano and hundreds of thousands of leaky propane tanks hooked to stoves.

More than 20 million people are crammed into the greater Mexico City metropolitan area. By comparison, Los Angeles County is about twice as large but has only about half as many people. And everybody here seems to be burning something. Tiny particles lodge under contact lenses and deep in lungs, stoking allergies and worse. Colds last longer. And asthma sufferers really suffer.

It's got the whiff of the familiar to chemist Jeffrey Gaffney, 56, who grew up in Riverside and is here studying how soot affects weather for the U.S. Energy Department. Mexico City, he said, is a lot like Los Angeles in the 1960s and 1970s.

Although it has improved in the last few years, Mexico City's air quality most days still falls short of basic standards. This, despite the cleansing effect of a rainy season that runs from June to September.

Scientists already have tracked urban pollution as it moves from continent to continent -- from China to the West Coast of the United States, and from the Eastern Seaboard to Europe. This study examines regional movement.

Scientists and graduate students have been working 14-hour days to measure the giant plume of gases, dust and particles that rises out of Mexico City each day and generally drifts to the northeast, sometimes as far as the Gulf of Mexico.