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New York, London, Tokyo Rated Cleanest, Mexico City Dirtiest of Big Cities

December 1, 1992 GMT

GENEVA (AP) _ New York, London and Tokyo have the cleanest air of the world’s largest cities, and Mexico City the dirtiest, a U.N. study said Tuesday. Los Angeles’ ozone pollution is among the world’s worst.

Air in many developing countries is getting more dangerous, with heavy metals like mercury and cancer-causing chemicals increasingly entering the mix, it said.

The study by the World Health Organization and U.N. Environment Program was presented to reporters by Dr. Michael Gwinn of the environment agency.

It warned that air pollution will increasingly cause health problems as more people move to cities, including damage to the heart, lungs and brain. A U.N. prediction reckons 47 percent of the world’s population will live in urban areas by the year 2000.

Cities in developed countries have done much to improve air quality, but poorer lands lack the money to tackle the problem, the report’s authors said.

The two agencies examined the air quality of 20 ″megacities,″ which they said already had populations of at least 10 million or were expected to reach that number by 2000.

They said it was the first comprehensive overview of world air pollution.

The problems of Mexico City, which is ringed by mountains, are made worse because of the thin air at its 7,349-foot elevation.

It was the only city with as many as four pollutants at twice the highest levels recommended by WHO - sulfur dioxide, dust, carbon monoxide and ozone.

But all the major pollutants - which also include lead and nitrogen oxides - were present in each of the cities, the report said.

Some problems cited:

-Dust storms frequently foul the air of Beijing; Cairo, Egypt; New Delhi, India; Karachi, Pakistan, and Mexico City.

Motor vehicles are the main source of pollution in most of the cities, especially in Los Angeles. Its 8 million registered vehicles were double the number in second-place Sao Paulo, Brazil.

Los Angeles was one of four cities reporting ozone levels at more than twice the WHO limit.

Ozone is particularly a problem in sunny cities with lots of cars. It is formed when sunlight works on chemicals in auto exhaust once they are in the atmosphere.

Open trash burning is a major problem in developing countries, the report said. ″There is no excuse for this going on,″ Gwinn said.

Seoul, South Korea; Karachi; Cairo; and Beijing each reported two pollutants at levels of more than double the WHO limits, and nine cities - Bangkok, Thailand; Bombay, Calcutta and New Delhi, India; Jakarta, Indonesia; Los Angeles; Manila, the Philippines; Sao Paulo; Shanghai, China, and Tokyo were each double the WHO limits for one pollutant.

London was low in all areas but carbon monoxide, a frequent element of car exhaust. New York had low pollution in three areas but reported moderate to heavy pollution from carbon monoxide and ozone.

Tokyo had a serious problem with ozone, but reported only low levels of pollution in other areas.

The report cited incomplete reports from Rio de Janeiro, Brazil, and Buenos Aires, Argentina.

Moscow has problems with dust, carbon monoxide and nitrogen oxides, but did not report levels of ozone and sulfur dioxide. Sulfur dioxide has been a problem in the past there, the report said, casting doubt on the Russian data supplied.