SAN LUIS POTOSI, Mexico — Gabriela Ochoa was born and raised in Mexico City, and for 29 years she put up with the polluted air, gnarled traffic and stomach-wrenching stress of the world's largest city.
Then her 5-year-old daughter began to have trouble breathing.
"We took her to many doctors," Ochoa said. "They told me she was suffering from the pollution and had to get out."
In August, Ochoa, her husband and daughter joined the growing ranks of middle-class Mexicans who have given up on the capital and moved to suburbs or nearby provincial cities such as San Luis Potosi, Aguascalientes, Queretaro and Toluca.
While droves of the nation's poor continue to arrive in Mexico City in search of jobs, an estimated 1.5 million people--largely skilled laborers and white-collar workers--have fled the capital since 1985, the year it was convulsed by a deadly earthquake.
Increasingly, businessmen also are looking for ways to move their plants and offices out of Mexico City. Foreign companies say they are finding it more difficult and expensive to attract high-quality executives to the capital, primarily because of the pollution. Lawyers back home have raised concerns about potential lawsuits if employees should suffer long-term health problems after working there.
The migration is causing trouble for many of the ballooning provincial cities, as well. Their feeble infrastructures are overtaxed by the rapid and unplanned growth.
San Luis Potosi, a cobblestoned, colonial city of about 390,000 in 1982, apparently has more than doubled its population in the last decade. Now, honking cars jam its narrow streets, the industrial park produces a lake of toxic waste, and a cloud of brown air hovers over the city, all of which raises fears that San Luis Potosi is destined to become another Mexico City.
Locals, called Potosinos, often blame migrants for the mess. Chilangos-- the name given to Mexico City residents because of their fondness for chili--are not altogether welcome here, as homespun jokes make clear.
In one, a visitor asks what happened to bumper stickers that read "Be a Patriot, Kill a Chilango. " Answers the Potosino: "We got rid of them because 20 family members would come to the funeral and 10 would stay."
Although the majority of the migrants may be industrious and well-educated--supervisors, engineers and mid-level managers, according to Mayor Guillermo Pizzuto--many Potosinos view them as hyperactive and unwanted competition.
"They're hysterical," said cabdriver Jose Cruz. "They get angry at the smallest thing, and they're always running from one place to another."
Market vendor Maria Elena Saucedo observed of them: "They're aggressive. They strike before being struck. Whenever there's a crime, a robbery or rape, people say it was someone from Mexico City. My family's from Aguascalientes, and it's the same there."
Saucedo said Chilangos are arrogant because they are used to big-city life, with its good universities and fancy discotheques. "They think they're better than we are even if they have less," Saucedo said. "It's always, 'Look what we had in Mexico City. Mexico, Mexico, Mexico.' So what did they come here for?"
That is a question just about any Mexico City resident can answer, whether or not he has chosen to leave: smog that is far greater than world health standards nearly every day, a crush of 3 million vehicles, rising housing costs, water shortages, noise pollution and crowds.
For many, Mexico City simply has become unbearable.
"This city is killing itself," said Mexico City cabbie Jose Lorenzo Marquez. "I have got to get my kids out of here."
After 18 years as an airport personnel employee, Marquez quit and took his severance pay. As soon as he sells his house, he is moving his wife and three children to Veracruz, where his parents were born.
"Here in Mexico City, the sun doesn't come out," Marquez said. "People have lost the joy of conversation and good food. I used to run every day for exercise, but now I don't, because they say it's not good for you."
Marquez said he goes home at midday to bathe away grime from the air. After driving a taxi for 12 hours, he usually has a headache at night. "I feel bad every day, but some days I feel worse," Marquez said. "I am going to buy a house in Veracruz and open a business there."
Many business leaders say they would gladly leave if they could, but Mexico is such a highly centralized country that they must remain. With few exceptions, the important banks, universities, corporations and government and cultural institutions are headquartered in the capital.
"This is New York, Washington, Chicago and Los Angeles," said Steve Knaebel, president and general manager of Cummins motor company in Mexico. "This is where the action is. If I go for a major loan, I don't go to a bank in San Luis Potosi, I come here."