Reduced ultrafine particle levels in Sao Paulo's atmosphere during shifts from gasoline to ethanol use

Author(s)

Salvo, Alberto ; Brito, Joel ; Artaxo, Paulo ; Geiger, Franz M.

• Document type: Journal article
• Source: NATURE COMMUNICATIONS; v. 8, JUL 18 2017.
• Web of Science Citations: 5

Abstract

Despite ethanol's penetration into urban transportation, observational evidence quantifying the consequence for the atmospheric particulate burden during actual, not hypothetical, fuel-fleet shifts, has been lacking. Here we analyze aerosol, meteorological, traffic, and consumer behavior data and find, empirically, that ambient number concentrations of 7-100-nm diameter particles rise by one-third during the morning commute when higher ethanol prices induce 2 million drivers in the real-world megacity of Sao Paulo to substitute to gasoline use (95% confidence intervals: +4,154 to +13,272 cm(-3)). Similarly, concentrations fall when consumers return to ethanol. Changes in larger particle concentrations, including US-regulated PM2.5, are statistically indistinguishable from zero. The prospect of increased biofuel use and mounting evidence on ultrafines' health effects make our result acutely policy relevant, to be weighed against possible ozone increases. The finding motivates further studies in real-world environments. We innovate in using econometrics to quantify a key source of urban ultrafine particles. (AU)

• FAPESP's process: 13/25058-1 - Impact of Manaus urban pollution on gases and particulate matter composition in the Amazon forest
• Grantee: Joel Ferreira de Brito
• Support type: Scholarships in Brazil - Post-Doctorate
• FAPESP's process: 13/05014-0 - GoAmazon: interactions of the urban plume of Manaus with biogenic forest emissions in Amazonia
• Grantee: Paulo Eduardo Artaxo Netto
• Support type: Research Program on Global Climate Change - Thematic Grants