Are residents really breathing easier in Mexico City?

On a clear day, Liliana Cordero can see ... maybe not forever, but at least as far as the mountains that surround Mexico City.

And since she saw the mountains more in 1999, the anthropology student agrees when the city government announces that the air of what has often been called the most-polluted city in the world is getting better.

"There's still a lot of room for improvement, but we're having fewer emergency days when you can't drive. The sky is blue more often, and I'm noticing less throat irritation," says Ms. Cordero, studying on a sunny morning in a city square.

Having closed out 1999 with only three smog emergencies covering five days, Mexico City's government is declaring last year the cleanest of the decade in terms of air quality. But some environmentalists call the claims political hot air. Although they agree that Mexico City's air is gradually getting cleaner and healthier, they insist the improvement has more to do with over a decade of antipollution measures than with the actions of a two-year-old government.

"It's very precipitous to cry victory, and especially misleading for this government to say, 'We did it!'" says Gustavo Alanis, president of the Mexican Center for Environmental Law in Mexico City.

"There are some improvements that are the result of at least 12 years of hard work and big investment by international institutions and countries.... It's not the work of Crdenas," he says, referring to Cuauhtmoc Crdenas, the city's former mayor, now running for president.

"There have been improvements in the air," adds Gabriel Quadri, director of the Center for Private Sector Studies for Sustainable Development. "But it is excessive and frivolous to correlate the actions of the government over the last two years with the progress ... started in the late '80s."

What's more, Mr. Quadri says the air-quality improvements registered so far could easily be reversed by a spate of adverse weather conditions. "The ozone level is determined to a great extent by factors like cloud cover and ultraviolet light that it just so happens were favorable last year," he says. The city did not register any real reduction in emissions over the past two years, Quadri says. So, the return of unfavorable climatic conditions could reverse both the improvements and the perception of progress.

He also notes that the number of cars in the city and sales of gasoline are rising as the economy strengthens. The Mexico City government's glowing air-quality report also received a cold response from the national Health Secretariat, which divulged a new study showing that the city's smog conditions are stunting lung development among children. The report said the chief cause of the problem is ozone, a poisonous oxygen gas not to be confused with the atmosphere's beneficial ozone layer. But even that report noted that in 1999 the average Saturday ozone count, according to an internationally used scale, was 145, compared to 211 in 1991.

Not all Mexico City residents are convinced of the improvements, anyway. Rebecca Yoma, a lifelong resident of the capital, says she didn't notice any difference in 1999, but does credit the Crdenas government with making an effort.

"The solution can't be piecemeal, and it can't be local," says the archaeologist, who adds that politicians must confront strong interest groups.

Less than half the population of the Valley of Mexico is inside Mexico City. And while Ms. Yoma would like to see the city implement a pro-bicycle policy, she says the automobile lobby would oppose such a move.

Environmental-law expert Alanis says Mexico City actually has good environmental laws: "Our problem is enforcement."

The city's auto-emission verification program reflects a vast sea of corruption and inefficiency, he says.

"It's common to hear people talk about the 'godmother' car the verification center keeps on hand." For a price, Alanis says, they'll run emissions tests on it if your car will likely fail.

He adds that getting around enforcement must change" if "we're going to clean up our air. "

(c) Copyright 2000. The Christian Science Publishing Society