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The motor vehicles are the main source of atmospheric pollution, especially carbon monoxide, hydrocarbons and nitrogen oxides (NOx). To reduce these emissions for environmentally acceptable levels, Europe and the United States have developed control programs, where are set emissions limits for new vehicles, which are gradually reduced over time and the compliance must be done through standardized tests in laboratories. However, Europe is facing a problem: NOx level in the cities is not being reduced in the same proportion of the homologation limits, due to two factors: the poor representativeness of the test procedures in comparison of the “real world” and the use of engine management software that produces low pollutants just in laboratory tests. Several studies about real world emissions have pointed to vehicles, approved in the laboratory, emitting in the streets about 7 up to 40 times more NOx than the homologation limit.

Excessive noise level in urban centers is a problem which causes many health diseases and, although gaseous emissions are getting down, noise remains high and exceeds the recommended levels from World Health Organization (WHO). The first step to deal with this is the Noise Map, a software tool that represents the noise level through a color scale over a map but usually without show the reasons of such level and neither evaluating the presence of motorcycles in the composition of the traffic flow. This article analyzes the noise contribution and particularities of different types of vehicles in the traffic of Sao Paulo City and looks for solutions to a quieter environment. It was measured road traffic noise of cars, motorcycles and buses and identified the main problems that contribute to keep it high. Cars appear as the most relevant source and their tires as the main influence in the Equivalent Sound Level (Leq).