Ozone levels in Sao Paulo drop 20% with switch from ethanol to gasoline

摘要

A Northwestern University study by an economist and a chemist reports that when fuel prices drove residents of Sao Paulo, Brazil, to mostly switch from ethanol to gasoline in their flexible-fuel vehicles, local ozone levels dropped 20%. At the same time, nitric oxide and carbon monoxide concentrations tended to go up. The four-year study is the first real-world trial looking at the effects of human behaviour at the pump on urban air pollution.