PM speciation and sources in Mexico during the MILAGRO-2006 Campaign

Abstract

Abstract. Levels of PM10, PM2.5 and PM1 and chemical speciation of PM10 and PM2.5 were measured during the MILAGRO campaign (1 to 31 March 2006, but extended in some cases until 6 April) at four urban, one suburban, two rural, two rural background sites with different degree of industrial influence in the Mexico City Metropolitan Area (MCMA) and adjacent regions. PM10 and PM2.5 daily levels varied between 50–56 μg/m³ and 24–46 μg/m³ at the urban sites, 22–35 μg/m³ and 13–25 μg/m³ at the rural sites, and 75 μg/m³ and 31 $\\mu $g/m³ at the industrial hotspot, respectively; lower than those recorded at some Asian mega-cities and similar to those recorded at other South American cities. At the urban sites, hourly PM2.5 and PM1 concentrations showed a marked impact of road traffic emissions (at rush hours), with levels of coarse PM remaining elevated during daytime. At the suburban and rural sites, different PM daily patterns were registered according to the influence of the pollution plume from MCMA and also on local soil resuspension. The speciation studies showed that mineral matter accounted for 25–27% of bulk PM10 at the urban sites and a higher proportion (up to 43%) at the suburban and rural sites. This pattern is repeated in PM2.5, with 15% at urban and 28% at suburban and rural sites. Carbonaceous compounds accounted for a similar proportion at the urban sites (24–32% in PM10, and up to 37% in PM2.5), markedly reduced at the suburban and rural sites (17% in PM10, and 23–38% in PM2.5). The secondary inorganic aerosols accounted for 10–20% of bulk PM10 at urban, suburban, rural and industrial sites, with a higher proportion (40%) at the industrial background site. A relatively high proportion of nitrate in rural sites was present in the coarse fraction. Typically anthropogenic elements (As, Cr, Zn, Cu, Pb, Sn, Sb, Ba, among others) showed considerably high levels at the urban sites; however levels of particulate Hg and crustal trace elements (Rb, Ti, La, Sc, Ga) were generally higher at the suburban site. Principal component analysis identified three common factors: crustal, regional background and road traffic. Moreover, some specific factors were obtained for each site.

Variation in the Composition and In Vitro Proinflammatory Effect of Urban Particulate Matter from Different Sites

“…For instance, the R-S had the largest average values for C 1 and also induced the highest TNFα levels in both cell lines and the highest IL-6 levels in THP-1 cells. This component included elements and endotoxins linked to soil [26][27][28]. Previous studies from our group support that PM-induced proinflammatory responses result from complex interactions among PM constituents, where endotoxin adds to but does not explain all observed effects [14,29].…”

Air pollution is associated with brainstem auditory nuclei pathology and delayed brainstem auditory evoked potentials

“…The geographic areas selected for this study were: Southwest MC (SWMC) and Polotitlán. SWMC has had concentrations of O3 and PM2.5 above the USA National Ambient Air Quality Standard (NAAQS) for several years (Bonner et al, 1998;Bravo-Alvarez and Torres-Jardón, 2002;Rosas-Pérez et al, 2007;Molina et al, 2007;Querol et al, 2008;Estrada-Garcia et al, 2004).…”

“…Mexico City children in this study were exposed to significant concentrations of ozone (O 3 ), and particulate matter (PM) for their entire life (Bravo-Alvarez and Torres-Jardón, 2002; Rosas-Pérez et al, 2007;Molina et al, 2007;Querol et al, 2008). The climatic conditions in MC are relatively stable, thus, pollutant concentrations are consistent year after year (Bravo-Alvarez and Torres-Jardón, 2002).…”

“…the last 20 years, exposures of today's children begins in utero and impacts neurological function for their entire life (Bravo-Alvarez and Torres-Jardón, 2002). MC children are frequently exposed all year long, at least several hours per day, to a significant burden of air pollutants, including concentrations above the current USA standards for ozone (O 3 ), and particulate matter < 2.5 m in diameter (PM 2.5 ) , as well as lipopolysaccharides-associated with PM (PM-LPS) (Bonner et al, 1998;Bravo-Alvarez and Torres-Jardón, 2002;Rosas-Pérez et al, 2007;Molina et al, 2007;Querol et al, 2008).…”

“…In the present study, we tested the hypothesis that, as compared to children residing in an urban area with concentrations of main criteria air pollutants below the current USA standards, clinically healthy MC children would have altered BAEPs as a manifestation of neuroinflammation associated with severe exposure to air pollutants (Bonner et al, 1998;Bravo-Alvarez and Torres-Jardón, 2002;Rosas-Pérez et al, 2007;Molina et al, 2007;Querol et al, 2008;Estrada-Garcia et al, 2004).…”