WAITING at a Pemex gas station on Insurgentes Avenue for his late-model taxi to be refueled, Marcus Maurecio smiles and shakes his head: ``No. I'm not using Magna Sin, it's too expensive.'' In the world's most polluted city, environmental conscientiousness comes slowly. But it is coming.
Last month, the government-owned oil company Petroleos Mexicanos (Pemex) began selling Magna Sin, a high-octane unleaded fuel, nationwide.
Magna Sin is part of a federal and local effort to reduce the noxious fumes generated in this mega-metropolis of 18 million people. Each winter, the emissions of 35,000 factories and some 3 million cars are trapped in this 1.5-mile-high mountain valley by thermal inversions.
Earlier this month, the Mexican government announced details of a new 7.3 trillion peso (US $2.5 billion) air-pollution control program. Sixty percent of the funds will come from Mexico, the rest from foreign loans. The money will be spent on increasing the supplies of unleaded fuel, extending the ``Metro'' subway system (considered underdeveloped for a city of this size), planting 100,000 trees, and installing pollution-control devices on public transports and industrial plants.
The engines of city buses, which pollute the air at rates 300 times higher than buses in the United States, are being repaired and fitted with antipollution devices. The 1991 model cars, which are on sale now, are equipped for the first time with catalytic converters to take full advantage of the new fuel.
Since January, city residents have had to leave their cars - which produce 80 percent of the air-born contaminants - at home one day a week. Mayor Manuel Camacho Sol'is told a United Nations meeting in New York on Sept. 3 that the ``Hoy no circula'' [today no driving] program was part of a 28-point program that has reduced the presence of contaminants by 23 percent this year.
Ecologists and private researchers question the validity of this claimed reduction.
``Gasoline sales are up and 175,000 new cars have been sold. Also, many people are buying cars to use on the one day they cannot use their regular vehicle,'' says a skeptical Ivan Restrepo, director of the Center for Ecodevelopment here.
BUT the scientists agree that carbon monoxide and nitrogen oxide levels are down 5 to 10 percent since January. Measured amounts of other contaminants are no longer increasing.
``The biggest benefit of Hoy no circula is not the lowering of indexes,'' says Luis Manual Guerra, director of the Independent Institute of Ecological Research, which conducts daily atmospheric testing. ``The main benefit is that people are starting to think about how their own habits affect the environment.''
There was speculation that ``Hoy no circula'' won't be around much longer. But Mayor Camacho announced earlier this month that it would continue. ``Eighty-percent of the public supports it now. But if support drops below 60 percent we won't continue. And, there is strong economic pressure against it,'' says Ramon Ojeda, director of pollution prevention and control in Mexico City.
The opposition comes mostly from small businesses with only one or two delivery trucks. They, too, must park their vehicles one day a week. In other cities, such as Singapore and Athens, where this type of program has been tried, support waned after a couple of years.
Many of the changes being made and considered aren't likely to produce blue skies over Mexico City for another 10 to 15 years. For example, only about 15 percent of car owners here are likely to switch to Magna Sin in the first year, predicts one city official.
But Magna Sin is considered important because it replaces a low-lead Pemex gasoline, known as Extra. The chemical additives in this fuel sent ozone levels skyrocketing. Studies have linked high ozone levels with damage to lungs. The World Health Organization (WHO) recommends that people not be exposed for more than one hour to more than 0.11 parts per million of ozone each year. In the first six months of this year, ozone levels were over the WHO limit for 380 hours.
The health implications of continued use of the less-expensive leaded gasoline are also not widely known here. If the government wants to get drivers like cab driver Marcus Maurecio to use Magna Sin, says Mr. Guerra, they should take a page from West Germany's antipollution book.
In 1988, Germany weaned consumers from buying leaded gas by transferring the higher production cost of unleaded fuel to the pump price of leaded fuel.