The paper compares the impact of the private car on atmospheric pollution in São Paulo, Paris and Montreal, cities which contrast by their size, their level of economic development, their rate of growth and their urban form. In the three case studies, the same methodology is applied to estimate the evolution of the car fleet and of traffic. The data used come from surveys realised between 1973 and 1997 and the projections at the horizon 2020 are made with a demographic based model. The results show that the traffic grows slightly more than the car fleet in São Paulo and Paris, and much more rapidly in Montreal. Thus, in spite of important differences in population size, the absolute growth in vehicles-km is similar in the three urban regions. However, while this growth is generated mainly by the inhabitants of the outer suburbs in the two urban regions of the North, in the case of São Paulo it comes from the central city. The technical characteristics of the fleet differ (gasohol in Brazil, diesel in France, gasoline in Montreal) but these differences will tend to disappear with the introduction of anti-pollution legislations. The three case studies share common trends, but the local effects of traffic on air quality appear more severe in Sao Paulo due to its concentration in the central city.
Abstract