Abstract
The frequent episodes of high concentrations of ozone and of inhalable particulate matter occurring in the Metropolitan Area of Sao Paulo (MASP) are primarily associated with vehicle emissions. The objective of this study was to evaluate the impact of the use of reformulations of the gasoline-ethanol blend known as gasohol and of ethanol on the ozone formation. A three-dimensional photochemical model was employed to estimate the sensitivity of ozone and evaluate the implementation of emission scenarios, considering various fuel formulations, in the MASP. The base case ozone concentrations were consistent with the observations over six air quality monitoring stations located in the MASP, suggesting that the model can be used to evaluate the impact that various emission scenarios would have on ozone levels. Six scenarios were analyzed; scenarios 1 to 5 involved reductions in compounds found in gasohol in various proportions compared with the base emission inventory and scenario 6 specified that the entire light duty fleet would burn pure ethanol. In scenario 3 (reductions in olefins, aromatics and benzene) and scenario 5 (reductions in the five species that are associated with higher ozone sensitivity), ozone concentrations were below the national standard only at the air quality monitoring stations (not domain-wide). Our results suggest that implementing scenario 6 would improve air quality in the MASP.
Highlights
The Metropolitan Area of São Paulo (MASP) is classified as a megacity
The comparison between predicted ozone concentrations and those observed at two groups of air quality station located in the MASP is presented in Fig. (2)
The results indicated that the E85 scenario would increase ozone concentrations and have ill effects on the health of the population
Summary
The Metropolitan Area of São Paulo (MASP) is classified as a megacity. It is the largest urban area in South America, with a population of over 17 million people and a fleet of approximately 7.8 million vehicles, the latter being responsible for more than 90% of all carbon monoxide (CO), hydrocarbon (HC) and nitrogen oxide (NOx) emissions in the area [1]. Ozone and inhalable particulate matter levels routinely exceed the Brazilian national ambient air quality standards for hourly and daily concentrations, 160 μg m3 ( 82 ppbv) and 150 μg m-3, respectively [4, 5]. Ethanol accounts for approximately 34% of the fuel burned by the fleet in the MASP. Flex-fuel vehicles (running on either gasohol or ethanol) and
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