Author(s)

J.G. Kretzschmar

Abstract

Based on the WHO/UNEP megacity study published in 1992, and new data and information that became available in the period 92/96, this paper focusses on the past and present ambient air pollution levels in the world's ten largest megacities. Persisting (serious) ozone levels in the four biggest metropolitan areas, namely Tokyo, Mexico City, Sao Paulo and New York City lead to the conclusion that, despite significant efforts, motorvehicle emissions remain the problem to be solved. 1 Introduction If megacities are defined as urban agglomerations with a population exceeding 10 million, there are presently some 15 megacities on our globe, but by 2000 this will become 20 to 25. It is obvious that such a concentrations of active human beings and the corresponding industrial and commercial activities do create man

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