Basic statistics of PM and PM in the atmosphere of 2.5 10 Mexico City

The high levels of fine particulate matter in Mexico City are of concern since they may induce severe public health effects as well as the attenuation of visible light. Sequential filter samplers were used at six different sites from 23 February to 22 March 1997. The sampling campaign was carried out as part of the project ‘Investigaci´on sobre Materia Particulada y Deterioro Atmosf´erico-Aerosol and Visibility Evaluation Research’. This research was a cooperative project sponsored by PEMEX and by the US Department of Energy. Sampling sites represent the different land uses along the city, the northwest station, Tlalnepantla, is located in a mixed medium income residential and industrial area. The northeast station, Xalostoc, is located in a highly industrialized area, Netzahualcoyotl is located in a mixed land use area, mainly commercial and residential. Station La Merced is located in the commercial and administrative district downtown. The southwest station is located in the Pedregal de San Angel, in a high-income neighborhood, and the southeast station located in Cerro de la Estrella is a mixed medium income residential and commercial area. Samples were collected four times a day in Cerro de la Estrella ŽCES., La Merced ŽMER. and Xalostoc ŽXAL. with sampling periods of 6 h. In Pedregal ŽPED., Tlalnepantla ŽTLA. and Netzahualcoyotl ŽNEZ. sampling periods were every 24 h. In this paper the basic statistics of PM2.5 and PM10 mass concentrations are presented. The average results showed that 49, 61, 46, 57, 51 and 44% of the PM10 consisted of PM2.5 for CES, MER, XAL, PED, TLA and NEZ, respectively. The 24-h average highest concentrations of PM2.5 and PM10 were registered at NEZ Ž184 and 267 g m3. and the lowest at PED Ž22 and 39 g m3.. The highest PM10 correlations were between XAL-CES Ž0.79., PED-TLA Ž0.80.. In contrast, the highest PM2.5 correlations were between CES-PED Ž0.74., MER-CES Ž0.73. and TLA-PED Ž0.72., showing a lower correlation than the PM10 one. The results of the PM10 from 12.00 to 18.00 h at CES and MER presented the highest variability and also the highest median concentrations, meanwhile XAL showed them from 06.00 to 12.00 h. The highest variability and median concentrations of PM2.5 were from 06.00 to 12.00 h for the three stations