HR: 14:40h
AN: A23C-02 INVITED     [Abstracts]
TI: Air Quality Impairment Associated to Local and Regional Pollutants Sources in the Megacity of Sao Paulo, Brazil
AU: * Andrade, M
EM: mftandra@model.iag.usp.br
AF: University of Sao Paulo, Department of Atmospheric Sciences, Sao Paulo, SP 05508-090, Brazil
AB: The Metropolitan Area of Sao Paulo (MASP), with more than 19 million inhabitants in 2006, about 2000 major industrial facilities, and more than 7 million vehicles based on diesel, gasoline, and ethanol, has 8051 km2. MASP is one of the biggest urban agglomerate in the world. Associated to its dimension many important problems appear and among them the bad air quality is one of the most important due to the human health effects. MASP is the richest area in Brazil representing 17% of Brazilian GNP in 2000. Not only the high pollutants concentration but also the accentuated modification of the land use in the area resulted in bad quality of life characterized by local and regional climate modification, as for instance the light rain suppression and the increase of the heavier rain. In MASP the air pollution has worsened due to the cumulative effects of population growth, industrialization and increased vehicle use. Currently there are about 7.2 million passenger and commercial vehicles: 93.5% light- duty and 6.5% heavy-duty diesel vehicles. Of the light-duty vehicles, approximately 76.3% burn a mixture of 78-80% (v/v) gasoline and 22% ethanol (referred to as gasohol), and 17.2% use hydrated ethanol (95% ethanol + 5% water), these data were obtained from the Sao Paulo Environmental Protection Agency. Over the past several years, ambient ozone concentrations in the MASP have reached levels of more than five times that considered protective of public health by the World Health Organization. In the wintertime, ozone levels routinely exceed the 160 ug/m3 hourly Brazilian National Ambient Air-Quality Standard. About 90% of the O3 precursors in the MASP atmosphere are emitted by the vehicle fleet. According to the official state EI of HC (hydrocarbons) emissions from mobile sources, 22% are from gasohol-powered vehicles, 15% from diesel-powered vehicles, 6% from ethanol-powered vehicles and 5% from motorcycles. In addition, a significant contribution to HC emissions comes from evaporative emissions, which constitute 48% of total HC emissions to the atmosphere. In the specific case of nitrogen oxides (NOx), 78% comes from diesel-powered vehicles, 13% from gasohol-powered vehicles, and 4% from ethanol-powered vehicles. One source of uncertainty is the lack of a vehicular emissions inventory (EI). To improve the vehicular EI for the light- and heavy-duty fleet, measurements of vehicle emissions in road tunnels located in the MASP were performed. On March 22-26, 2004 and May 04-07, 2004, respectively, CO, CO2, NOx, SO2, and volatile organic compounds (VOCs) emissions were measured in two tunnels: the Janio Quadros, which carries light-duty vehicles; and the Maria Maluf, which carries light-duty vehicles and heavy-duty diesel trucks. Pollutant concentrations were measured inside the tunnels, and background pollutant concentrations were measured outside of the tunnels. The mean CO and NOx emission factors (in g km-1) were, respectively, 14.6 ± 2.3 and 1.6 ± 0.3 for light-duty vehicles, compared with 20.6 ± 4.7 and 22.3 ± 9.8 for heavy-duty vehicles. The total VOCs emission factor for the Maria Maluf tunnel was 1.4 ± 1.3 g km-1. The main VOCs classes identified were aromatic, alkane, and aldehyde compounds. For the heavy-duty fleet, NOx emission factors were approximately 14 times higher than those found for the light-duty fleet. This was attributed to the high levels of NOx emissions from diesel vehicles. Other important results were related to the identification of the most reactive species for O3 formation using the metrics of MIR potential (Maximum Incremental Reactivity). For São Paulo the more reactive species are the alkenes and aromatics in the O3 formation.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0317 Chemical kinetic and photochemical properties
DE: 0345 Pollution: urban and regional (0305, 0478, 4251)
DE: 0365 Troposphere: composition and chemistry
DE: 6334 Regional planning (1880)
SC: Atmospheric Sciences [A]
MN: 2007 Joint Assembly