1 Fine Carbonaceous Aerosols in Monterrey Mexico: Chemical and Meteorological Relations Paper # 33600 Yasmany Mancilla, Alberto Mendoza Department of Chemical Engineering, Tecnológico de Monterrey, Campus Monterrey, Monterrey, México Pierre Herckes Department of Chemistry & Biochemistry, Arizona State University, Tempe, AZ Matthew Fraser School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, AZ ABSTRACT High levels of airborne particulate matter constitute a problem of great concern in the Monterrey Metropolitan Area (MMA), the third largest city in Mexico and the second most important industrial center. In this research study, 12-hour average fine particulate (PM 2.5 ) samples were collected during the spring and fall of 2011 and 2012. A total of 83 samples were analyzed for organic carbon (OC) and elemental carbon (EC). The carbonaceous fraction accounted for 28-55% of the PM 2.5 . The average OC/EC ratios ranged from 7.41 to 12.55 and the OC and EC were strongly correlated (R 2 =0.41-0.91). It was found that secondary organic aerosols constituted 73-99% and 31-59% of the total OC and PM 2.5 , respectively. During the spring, the daytime carbonaceous fraction was 1.6-1.8 times higher when compared to the nighttime fraction, whereas during the fall, it was 1.09- 1.15 times higher, indicating more variability in spring days compared to fall days. A defined temperature pattern was exhibited for the spring, while a different pattern for fall was exhibited. The relationship between the O 3 and wind speed indicated that the pollutant levels were influenced by transport events during the spring, while stagnation events predominated during the fall campaigns. Some strong correlations were observed between the OC and EC and gaseous pollutants (CO, NO x , and SO 2 ), indicating an anthropogenic origin of the carbonaceous material. INTRODUCTION A&WMA's 107th Annual Conference & Exhibition June 24-27, 2014 Long Beach, California