HR: 1400h
AN: A43A-13    [Abstracts]
TI: Trends In The Elemental Composition Of PM2.5 In Santiago, Chile From 1998 To 2006
AU: * Ruiz, P
EM: pruiz@hsph.harvard.edu
AF: Centro Mario Molina Chile, Avda del Valle 662, Santiago, Chile
AU: Oyola, P
AF: Centro Mario Molina Chile, Avda del Valle 662, Santiago, Chile
AU: Gramsch, E
AF: University of Santiago, Department of Physics, Santiago, Chile
AU: Moreno, F
AF: University of Santiago, Department of Physics, Santiago, Chile
AU: Koutrakis, P
AF: Harvard University, Harvard School of Public Health, Boston, MA , United States
AB: Santiago, Chile is one of the most polluted cities in South America. As a response, over the past 15 years, numerous pollution reduction programs have been implemented by the environmental authority, Comision Nacional del Medio Ambiente (CONAMA). This paper assesses the effectiveness of these interventions by examining the trends of PM2.5 and its elemental composition. Daily fine particle filter samples were collected in Santiago, Chile at a downtown location from April 1998 through March 2003. Additionally, meteorological variables were measured continuously. Annual average concentrations of PM2.5 decreased only marginally, from 41.8 μg/m³ for the 1998/1999 period to 35.4 μg/m³ for the 2002/2003 period. PM2.5 concentrations exceeded the annual U.S. EPA Standard of 15 μg/m³. Additionally, about 20% of the days exceeded the old standard of 65 μg/m³, while about half of the days exceeded the new standard (effective in 2006) of 35 μg/m³. Mean PM2.5 levels during the cold season (April through September) were three times as high as those observed in the warm season (October through March). Particulate mass and elemental concentration trends were investigated using regression models, controlling for year, month, weekday, wind speed, temperature and relative humidity. Significant decreases were observed for Pb, Br, and S concentrations, while minor but still significant decreases were observed for Ni, Al, Si, Ca and Fe. The larger decreases were associated with specific remediation policies implemented to remove lead from gasoline, the reduction of sulfur levels in diesel fuel, and the introduction of natural gas. These results suggest that the pollution reduction programs, specially the ones related to transport, have been effective in reducing various important components of PM. However, particle mass and other associated element levels remain high and it is thus imperative to continue the efforts to improve air quality, particularly, focusing on industrial sources. New results including data collected until August 2006 will also be presented.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0478 Pollution: urban, regional and global (0345, 4251)
DE: 4251 Marine pollution (0345, 0478)
SC: Atmospheric Sciences [A]
MN: 2007 Joint Assembly