section_path: Geography/Environment
section_name: Environment
paragraph_text: Environment
  
  Air pollution in some districts of the city exceeds local standards, mainly due to car traffic. The World Health Organization (WHO) sets a limit of 20 micrograms of particulate matter per cubic meter of air as a safe annual average. In an assessment carried out by the WHO among over a thousand cities around the world in 2011, the city of São Paulo was ranked 268th among the most polluted, with an average rate of 38 micrograms per cubic meter, a rate well above the limit imposed by the organization, but lower than in other Brazilian cities, such as Rio de Janeiro (64 micrograms per cubic meter). A 2013 study found that air pollution in the city causes more deaths than traffic accidents.
  
  The stretch of the Tietê River that runs through the city is the most polluted river in Brazil. In 1992, the Tietê Project began, with the aim to clean up the river by 2005. 8.8 billion reais was spent on the failed project. In 2019, the Novo Rio Pinheiros Project began, under the administration of João Doria, with the aim to reduce sewage discharged into the Tietê's tributary, the Pinheiros River.
  
  The problem of balanced water supply for the city - and for the metropolis, in general - is also a worrying issue: São Paulo has few sources of water in its own perimeter, having to seek it in distant hydrographic basins. The problem of water pollution is also aggravated by the irregular occupation of watershed areas, caused by urban expansion, driven by the difficulty of access to land and housing in central areas by the low-income population and associated with real estate speculation and precariousness in new subdivisions. With this, there is also an overvaluation of individual transport over public transport – leading to the current rate of more than one vehicle for every two inhabitants and aggravating the problem of environmental pollution.