27 de agosto del 2000
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Proyecto educativo


Cambio Climático
Proyecto de soporte a negociación ambiental

Cambio Climático

  Inter Press Service
Principal fuente de información
sobre temas globales de seguridad humana
Programa de las Naciones Unidas para el Desarrollo
Programa de las Naciones Unidas para el Medio Ambiente


L a t i n  A m e r i c a

Foul Air in the Big Cities

By Gustavo  González

Among the residents of Latin America's major urban areas, children and the elderly are the most vulnerable to the effects of air pollution. Health officials have recorded the growing incidence of respiratory ailments among these populations that can be traced to the high levels of contaminants in the air they are breathing.

SANTIAGO - The World Health Organization (WHO) declared Mexico City the most polluted metropolis in Latin America in 1999, but this dubious award had two close contenders: Sao Paulo and Santiago.

Days when air pollution measurements surpass internationally established limits are commonplace in the three cities, leading environmental groups to question government efforts to fight the problem.

At least three European embassies in Santiago have granted their employees extra vacation days during the winter months - the season when city air quality is at its worst. The staff members are under strict orders to leave the city on those days and go somewhere they can breathe ''clean air.''

In Sao Paulo, Miriam Duailibi, director of the non-governmental Ecoar Institute, told Tierramérica she thinks the government is not doing nearly enough to combat the problem. This city of more than 10 million people ''is the champion of carbon dioxide emissions,'' she said.

Serious public policies have not been implemented, said Duailibi, except for the rotation schedule that bans one-fifth of the motorized vehicles from circulation each day. Similar measures are also in effect in Santiago and Mexico City.

The gas emissions from cars and from fixed sources of combustion include carbon dioxide, carbon monoxide, sulfur dioxide, nitrogen oxides and ozone, and are the target of pollution-fighting campaigns.

But the results of such campaigns so far have not been very encouraging. Officials in Mexico City launched a plan a decade ago that called on drivers to leave their cars at home on certain days, depending on the vehicle license number. To get past the ban, many simply bought a second car.

''That program is the clearest proof that people in the capital never understood the ecological sense of not using their cars. They ended up saturating the city with old vehicles that pollute the air even more,'' commented Margarita Castillejos, an expert from Mexico's Metropolitan Autonomous University (UAM).

In Santiago, meanwhile, authorities established in the mid-1990s that new cars in the capital's metropolitan area had to be equipped with catalytic converters and use unleaded gasoline. But the measure did not achieve the desired reductions in air pollution.

The Institute of Ecological Policy and other environmental organizations in Chile launched a campaign to extend the restrictions against leaded-gas burning automobiles.

In early August, the Chilean government, under president Ricardo Lagos, finally approved a law to limit the circulation of leaded gas-burning vehicles, but there are already at least four automobile associations preparing to fight the measure in court. The law is slated to take effect next year.

Chile readjusted its emissions measuring standards in 1998, allowing officials to declare air pollution alerts when the concentration of particles per cubic meter surpasses 200, a state of pre-emergency at 300 and a full air quality emergency when it reaches 400 particles per cubic meter.

The next step is for environmental authorities to incorporate standards to measure fine particulate matter.

In 1998 there were 89 days in Santiago when the heavy particulate matter measurements (PM10) exceeded acceptable limits, leading to an 11 percent increase in the number of hospital visits for respiratory illnesses among newborns.

A recent study by Luis Cifuentes, at the Catholic University of Chile, found that between four and 11 percent of the deaths recorded in Santiago can be attributed in some measure to environmental contamination.

The Cifuentes report covers data from 32 Santiago municipal districts collected from 1988 to 1996. It connects the incidence of high levels of air pollution with rising rates of non-accidental and non-violent deaths.

In Mexico, a UAM study of children under 12 months old revealed that for every increase of 10 heavy particulate pollutants per cubic meter of air there is a 6.3 percent increase in infant mortality.

The study was performed in Mexico City's southwestern districts that, because of prevailing winds and the mountains encircling the area, receive the contaminants emitted by some 35,000 industries located across the northern periphery.

Research by the national Secretariat of Health shows that minors who have had prolonged exposure to pollution suffer physiological changes, including accelerated lung development, and a series of health ailments, leading to more doctor visits and increased school absenteeism .

''In the case of people over age 65 with some respiratory or cardiovascular ailment, for every 10 additional microns per cubic meter of PM10 particles there is a 1.4 percent increase in mortality,'' Castillejos said.

In the Brazilian mega-city of Sao Paulo, the latest studies indicate a reduction in traditional urban air pollutants. But now there is an increased presence of ozone, produced by the chemical reaction between nitrogen dioxide and oxygen. The process requires sunlight so ozone levels are generally higher during the summer months.

Ozone levels in 1999 shot up to 79 times the government's limit of 160 micrograms per cubic meter, a phenomenon attributed to the proliferation of cars in the city - currently estimated at six million - and to the evaporation of gasoline at service stations.

In contrast, authorities in the Venezuelan capital are conducting preliminary tests for ozone pollution, but most indications are that this city of four million inhabitants does not suffer problems in this respect.

Antonio Chacín, the specialist in charge of air quality issues at the Venezuelan Ministry of Environment, pointed out that current measurements show pollution levels are below the maximum limits established by the Environmental Protection Agency of the United States.

According to Chacín, 90 percent of the atmospheric pollution in Caracas is produced by vehicles, while industries do not represent a serious problem in this respect because many have relocated far from the capital or set up operations in satellite cities.

Additionally, Caracas has favorable weather conditions in which air currents ''serve to disperse pollutants,'' Chacín pointed out.

There are no campaigns currently underway to fight air pollution in the Venezuelan capital because the priority lies with other environmental problems, such as handling solid waste, combating urban sprawl and illegal settlements, and controlling the city's traffic.

The most recent major measure for reducing air pollutants was decreed in December 1998, requiring all new vehicles, beginning this year, to be equipped with a catalytic converter for ''green,'' or unleaded, gasoline.

''The results are going to be immediately evident,'' said an optimistic Chacín, who added that another law, passed in 1995, would most likely be revised so that fixed sources of atmospheric emissions will be inspected by environmental officials at least once a year.

* The author is an IPS correspondent.

Copyright © 2000 Tierramérica. Todos los Derechos Reservados

Young street clowns in Mexico City
Young street clowns in Mexico City/ Proceso Magazine