Ethanol fuel use in Brazil: air quality impacts

Brazil has a long history in the development of ethanol for use as a liquid fuel for vehicles. They have developed one of most efficient and economical systems for producing ethanol in the world. Brazil provides an example that many other countries would like to emulate. Using ethanol as a vehicle fuel has significant potential air quality impacts. This paper will review the available air quality and vehicle emissions data in Brazil, specifically focusing on vehicle related pollutants that may be impacted by the use of large quantities of ethanol in the fuel. The atmospheric concentrations of acetaldehyde (CH3CHO) and ethanol in Brazil are much higher than those in other areas of the world, while the concentrations of the single ring aromatic compounds and small carboxylic acids are more typical of observations elsewhere. Acetaldehyde and ethanol increase in vehicle emissions and nitrogen oxides (NOx) may increase when ethanol fuels are used. Both CH3CHO and NOx are very important contributors to photochemical air pollution and ozone (O-3) formation. There are very significant O-3 air quality problems in Brazil, most studied in the larger cities of Sao Paulo and Rio de Janeiro. These are issues that must be evaluated for other areas of the world that are considering the use of high ethanol content vehicle fuels.