Health Impact Assessment of Air Pollution in São Paulo, Brazil.  Epidemiological research suggests that air pollution may cause chronic diseases, as well as exacerbation of related pathologies such as cardiovascular and respiratory morbidity and mortality. This study evaluates air pollution scenarios considering a Health Impact Assessment approach in São Paulo, Brazil. We have analyzed abatement scenarios of Particulate Matter (PM) with an aerodynamic diameter <10 μm (PM10), <2.5 μm (PM2.5) and ozone concentrations and the health effects on respiratory and cardiovascular morbidity and mortality in the period from 2009 to 2011 through the APHEKOM tool, as well as the associated health costs. Considering World Health Organization (WHO) standards of PM2.5 (10 μg/m³), São Paulo would avoid more than 5012 premature deaths (equivalent to 266,486 life years'' gain) and save US$15.1 billion annually. If São Paulo could even diminish the mean of PM2.5 by 5 μg/m³, nearly 1724 deaths would be avoided, resulting in a gain of US$ 4.96 billion annually. Reduced levels of PM10, PM2.5 and ozone could save lives and an impressive amount of money in a country where economic resources are scarce. Moreover, the reduced levels of air pollution would also lower the demand for hospital care, since hospitalizations would diminish. In this sense, Brazil should urgently adopt WHO air pollution standards in order to improve the quality of life of its population.