Evolution of air pollution and impact of control programs in three Megacities of Latin America.

The present work discusses the problems of atmospheric pollution of three M egacities of Latin America (Mexico City, Sao Paulo and Santiago). The envir onmental pollution control programs implemented by the Government are revis ed and the evolution of pollution levels during the period of 1988-1995 at Santiago de Chile and Sao Paulo, but until 1997 at Mexico City, in order to evaluate the impact of these programs. During this period, a decreasing tr end is observed in the three cities in the levels of PTS, PM10, SO2, NO2, C O and O-3, although most of these contaminants still exceed the air quality standards. It must be emphasized that the largest impact has been on the l evels of SO2. We recommend the development of sustainable transport policie s; in this context, various strategies were proposed by the Organization fo r Economic Cooperation and Development (OECD) in the European Conference of Ministers of Transport. Additionally, public participation is important wh en decisions are taken on transport policies.