With continuing reductions in pollutant emissions
from stationary sources and progressive
controls applied to mobile emissions, aggregate
pollutant emissions declined during the 1980s in
Sao Paulo. A similar trend is beginning to emerge
in Mexico City. Despite these improving trends,
all the three metropolitan areas continue to have
some of the most severe vehicle-related air pollution
problems in the world. Without effective
controls, the continuing growth in motorization in
Latin America is likely to result in a deterioration
of urban air quality over the next decade, particularly
in the secondary cities. The severity of the
problem stems from two special characteristics:
an excessive and increasing dependence on the
private automobile for urban transport (as in
North America) and continuing use of outdated
and polluting motor vehicle and fuel technology.