Volume 10, No. 3, June 2010, Pages 193-211 PDF(5.32 MB)
Particulate Air Pollution in Mexico City: A Detailed View
Elizabeth Vega1, Silvia Eidels1, Hugo Ruiz1, Diego López-Veneroni1, Gustavo Sosa1, Eugenio Gonzalez1, Jorge Gasca1, Virginia Mora1, Elizabeth Reyes1, Gabriela Sánchez-Reyna1, Rafael Villaseñor1, Judith C. Chow2, John G. Watson2, Silvia A. Edgerton3
1 Instituto Mexicano del Petróleo, Eje Central Lázaro Cárdenas Núm. 152. Col. San Bartolo Atepehuacan. Delegación Gustavo A. Madero. 07730, México, D. F.
2 Desert Research Institute, 2215 Raggio Parkway, Reno, NV 89512-1095, USA
3 National Science Foundation, Arlington, Virginia, USA
A detailed view of particulate air pollution in Mexico City resulting from several analyses of data collected during four field campaigns is given. The resulting database from the March 1997 campaign was used to identify and quantify the contribution of particles to the atmosphere from different emission sources, to estimate transport and dispersion of pollutants and to estimate the amount of secondary organic carbon. Emission inventories of PM10, PM2.5 and ammonia were also calculated. Data from March 1997 and March 2002 campaigns were used to estimate aerosol optical properties and its impact on visibility, and measurements during March and November 2001 and March 2002 were used to obtain particle mass size distributions. Results showed that major contribution of PM2.5 were the mobile source emissions with 45%. Computer simulations were run for a wind blown dust episode and results agreed with observations. Particle concentrations were found to be inversely related to transport wind speed, and the highest pollutant dispersion was in the afternoon as calculated with the ventilation index. An average of 25% of the total organic carbon in the PM2.5 was associated to secondary organic aerosol estimated with an empirical model. Particles of sizes between 0.1 and 1.0 μm accounted for the highest mass concentrations and were associated mainly to primary emissions. The earlier visible light absorption peaks that appeared in the diurnal patterns were attributed to the elevated elemental carbon vehicular emissions during the heavy traffic hours while the later light scattering peaks were attributed to secondary aerosol formed photochemically in the atmosphere. Dairy and non-dairy cattle were the dominant sources according to the calculated emission inventory (EI) for ammonia. PM2.5 mobile sources derived from the EI were 11% whereas those estimated with the receptor model were 45%.
Particles; Fine aerosols; Air pollution; Mexico City.