Air pollution concentrations have been rapidly increasing in the major urban areas of Brazil caused mainly by the increasing use of vehicles. Policies to control car emissions in Brazil have relied basically on mandatory emission standards and subsidies for specific cleaner technology resulting in substantial decrease of car emission rates. Nevertheless, taxes on car sales, differentiated by vehicles' size and fuel, have also influenced car emission patterns. This paper analyses the compliance trend of the Brazilian fleet with environmental standards between 1992 and 1997....   [tags: Driving Air Pollution Emissions Global Warming]