Historical overview of air pollution in Sao Paulo metropolitan area, Brazil: influence of mobile sources and related health effects

摘要

Sao Paulo, Brazil, a metropolitan region with 39 municipalities and a continuous urban sprawl of 1,051 square kilometers and 16.5 million inhabitants, is responsible for 18% of the country's GNP and six million jobs. Over 40,000 industries and 5.7 million vehicles are registered there (25% of Brazilian car fleet). Three million cars circulate daily and 1 million drive in every day (350,000 trucks). The average car speed is around 17 km/h. These facts cause prohibition of circulation of 20% of passenger cars daily. During the 1970's air quality had an important influence from industrial sources. Nowadays emissions come mainly from vehicles (97.7% of CO; 96.2% of NO{sub}x; 97.8% of HC; 69.3% of SOx and 49.3% of particles). Light-duty vehicles are powered by gasohol (mixture of 78% gasoline and 22% ethanol) and by ethanol. Heavy-duty vehicles are diesel-oil fueled. Strong pollution control for stationary sources and a program of emissions reduction for new vehicles were put in practice, but only sulfur dioxide concentrations were greatly reduced. Levels of other pollutants are still above air quality standards during part of the year, in some neighborhoods. Higher number of cars neutralized efforts. Surveys conducted in the 1970's and 1980's showed correlation between air pollution levels and respiratory symptoms. Comparison done in 1998 showed that symptoms decreased in neighborhood where pollution control programs were successful, but increased where only sulfur dioxide levels were reduced and other pollutants increased. Nowadays, there is concern in relation to ozone's health effects for its concentrations surpass standards. This paper discusses air pollution in Sao Paulo, control programs, their efficacy, vehicle emissions and effects on health.