The main reason of air pollution in Brazil is due to the rapid population growing and also the fast increasing of urbanization. According to the World Bank, the most polluted cities of the country are São Paulo, Rio de Janeiro, Belo Horizonte and Curitiba.

Among those cities, Curitiba is the one that most seek a sustainable development. In 1970, Curitiba was the city that most grow in terms of population and infrastructure. The Curitiba government intended to mitigate the increase of cars in the city.

Therefore, strategies were applied such as: construction of better public bus track, the launch of extra large buses for high density routes. As a result of the strategies, Curitiba city fóssil fuel and air pollution was reduced.

São Paulo city is the second largest city in Latin America, behing Mexico city. The city faces the same problem. The traffic  increases significantly every year and so pollution also increase. In 1989, 50% of city smog come from industries and the other 50% from cars emission. In 1990, the pecentage was 10% and 90% respectively. Currently, the main reason is still because of cars.

Source: Corrosion Doctors