Throughout the 1980s and 1990s, biofuels - ethanol - was touted as the savior of the environment if it replaced fossil fuels. Former Vice-President Al Gore of Tennessee advocated them, environmental corporations pushed for lobied and finally, in 2005, they were mandated and subsidized.
It quickly became evident that the claims about ethanol were not based on science.
Ethanol was already big business in Brazil and given the benefit of time, scholars can now analyze their air quality as a result of switching from gasoline - and then back. Oddly, ethanol became too expensive so residents of São Paulo, Brazil switched from ethanol back to gasoline for their flexible-fuel vehicles.