New Gasoline Clouds Issue of Mexican Smog

Not long ago, Mexico’s government-owned oil company announced the introduction of a new gasoline designed to reduce the emission of air pollutants, especially poisonous lead, in motor vehicle exhausts.

“We have been very careful in the effective observance of environmental protection norms,” said Ramon Beteta, director of Pemex, the giant national oil company.

Not so, insist Mexican scientists, who assert that claims that the new gasoline significantly reduced toxic emissions from autos are so much hot air.

“The talk of a clean gasoline is nonsense,” said Manuel Guerra, director of the Institute of Ecological Investigation, a private environmental study group. “We in Mexico City are the victims of a bad experiment.”

Guerra and other environmental activists said that Pemex has merely traded one kind of pollution for another.

Lead levels may have been reduced, they concede, although they suspect the reduction is less than the government reports. On the other hand, chemicals added to boost octane in the new fuel are leaked into the atmosphere where, synthesized by sunlight, they form ozone, an element of smog harmful to respiratory health.

The ensuing debate over whether the new gasoline is an anti-pollution breakthrough is yet another controversial episode in the inconclusive campaign against dirty air in the world’s most populous city.

Health, Credibility

Not only is the health of 17 million residents of Mexico City at stake, but also the shaky credibility of the federal government, which sells the fuel and sets pollution standards.

The government seems bent on raising suspicions by refusing to divulge the formula of the gasoline. Repeated calls by The Times to officials in Pemex and the government Ecology and Urban Development Ministry failed to turn up anyone who knew the components of the recently introduced fuel. The officials merely responded that the new gasoline is better than the old.

“Yes, I have heard something about the ozone levels, but no, it’s not true,” said Salvador del Rio, a Pemex spokesman. “The new gasoline contributes to decreasing pollution levels.”

Earlier this month, Manuel Camacho Solis, the minister of urban development and ecology, said the new gasoline had contributed greatly to cleaning up the air.

“In such a brief time, other cities of the world have not achieved such results,” he asserted.

Such claims leave observers unimpressed.

Wants Ingredients List

“We feel defrauded,” said Homero Aridjis, a member of the Group of 100, an organization of prominent environmental activists. “Pemex must inform the public of the new ingredients in the gasoline. The silence is disturbing.”

Experts in the United States say that removing lead from gasoline is an important step in reducing harmful pollutants, but must be followed by others. Control of other harmful chemicals at least requires installation of anti-pollution equipment on motor vehicle exhaust systems and at storage places where gas vapors might leak into the air.

“Just changing the gasoline is not enough,” Bill Sessa, a spokesman for the California Air Resources Board, said. “To control smog, elaborate pollution controls are needed.”

There is some question whether, given this country’s economic problems, the government would consider requiring automobile manufacturers to install anti-pollution devices on cars manufactured here or force Pemex to tighten its pollution controls at storage tanks and at the filling station pump.

Winter of Discontent

Winter is the season for special discontent among environmentalists. It is the time of year when frequent thermal inversions produce the heaviest daily doses of pollution. A thermal inversion occurs when warm air in the upper atmosphere traps cooler air, and pollutants, below.

During most mornings in late fall and winter here, smoke from factories mixes with vehicular exhaust and dust to produce a thick haze that sometimes obscures buildings a few streets away. Then noses itch and run, coughs and sneezes increase. Children are more prone to lung ailments and old people gasp for air. Aerobics and jogging are not recommended because heavy breathing through the mouth offers a direct passage to the lungs for chemical irritants.

Recently, health experts estimated that 1 million Mexico City residents suffer frequent respiratory ailments. In winter, respiratory illnesses increase by 60%, the report added.

Hives and eye problems brought on by irritation are also commonplace.

Last January, after a month of especially severe pollution, the government announced measures to decrease airborne contaminants. But the proposals, which included staggered work shifts to break up commuter traffic jams and restrictions on driving in the downtown area, were never put into effect.

Introduced Low-Lead

In June, after years of unkept promises, Pemex introduced new low-lead gasolines, called Nova Plus and Extra Plus. A Pemex announcement said the new gasoline would reduce carbon monoxide emissions by 40%, hydrocarbons by 50% and lead pollution by 70%.

Lead was a special target because it affects the nervous system of children, causing learning disabilities that could last a lifetime.

Pemex skirted the question of how the necessary octane rating in the new lead-free gasoline would be maintained. The octane rating is a measure of a fuel’s ability to resist knocking or pinging in an engine.

When the lead compound that improves a fuel’s anti-knock properties is reduced or omitted, octane levels can be boosted either by repeated refining of the gasoline or by the addition of volatile chemical hydrocarbons.

It is the presence of the added hydrocarbons that worries scientists here; when released into the atmosphere, such chemicals react with other pollutants and sunlight to produce ozone.

Guerra, who is a chemist, said his institute had discovered two toxic hydrocarbons, xylene and toluene, in the new fuel. Both evaporate readily from liquid fuel into the atmosphere.

“The government is not taking into account the results of their actions,” Guerra said.

Hydrocarbons in Exhaust

He said that other hydrocarbons are present in the exhaust of the burned fuel. In other countries, such chemicals are removed from vehicular exhaust by catalytic converters that change the substances into harmless water and carbon dioxide compounds.

The converters are not required on cars manufactured in Mexico.

Besides vehicular exhaust, Mexico City, which produces one half of this country’s total volume of pollution, faces a host of other pollution problems not yet touched by regulation.

Although most contaminants here are produced by Mexico City’s 2 million motor vehicles, there are other sources. Factories, oil-burning public bathhouses and chemical vapors from laundries contribute significantly to pollution.

The mixture of filth is daunting: carbon monoxide that impedes the ingestion of oxygen; sulfur and nitrogen compounds that irritate the lungs and may reduce resistance to cancers; dust-borne intestinal viruses that bring on diarrhea and other digestive ailments, and hydrocarbons, the ozone producers.

Any gray winter morning confirms Mexico’s pollution problem. Nonetheless, environmentalists find themselves at odds with the government over the accuracy of official pollution readings. In response to complaints last year, the government began publicizing results from monitoring stations scattered throughout the metropolis.

24-Hour Average Readings

Most of the time, however, the readings show “good” or “fair” air in areas of the city known to be highly polluted. Moreover, the activists charge, on days that pollution has reached dangerous levels, the government has made no attempt to caution children or the elderly to curb their activities as required by law.

Daily pollution readings published by the government rate air quality over a 24-hour period. Such a system, critics contend, plays down the seriousness of pollution by averaging in nighttime readings when automobile traffic is light, factories are shut down and thermal inversions have dissipated.

Nonetheless, Camacho Solis defended the readings and suggested that ecologists are unduly alarming the public. “We should not give way to social panic nor frustration that would be produced if all the efforts one makes to attack the problem and the enormous expense (the efforts) generate are considered useless,” he said.