Survey of volatile organic compounds associated with automative emissions in the urban airshed of Sao Paulo, Brazil

The Metropolitan Region of Sao Paulo (MRSP), Brazil, is one of the largest metropolitan areas in the world (population 17 million, approx.) and relies heavily on alcohol-based fuels for automobiles. It is estimated that about 40% of the total volume of fuel is ethanol with some vehicles using pure e thanol and others a gasoline/ethanol blend. As such, Sao Paulo is an excell ent example of an oxygenates-dominated airshed of mobile sources and is mos t likely indicative of the future in heavily populated areas in the US such as Los Angeles where "oxy-fuels" are becoming an important replacement for the conventional pure petroleum-based fuels. In this work, we surveyed the ambient air to identify and quantify the organic compounds associated with the evaporative and exhaust emissions of these fuels and to begin to under stand the potential for human exposure. Because this was an initial test wi thout detailed prior knowledge of the airshed of the area, we applied two d ifferent air sampling methods for various time periods to assess the ambien t concentrations of a variety of polar and nonpolar volatile organic compou nds (VOCs). For quality assurance (QA), we collected all the samples in dup licate (whole-air samples in Summa canisters and adsorbent-based samples on Perkin-Elmer Air Toxics tubes) at various flow rates to test performance. All samples were collected over identical time frames, typically for 1-, 2- , and 4-h periods per day at six different locations over a period of I wee k. Overall Sao Paulo results demonstrate that mean concentrations of single -ring aromatics are 2-3 times higher, volatile aldehydes are 5-10 times hig her, and simple alcohols 10-100 times higher as compared to results of a re cent study performed by EPA in the Los Angeles basin. C-4-C-11 n-alkanes we re only slightly elevated in Sao Paulo. Published by Elsevier Science Ltd.