F. Raes, R. Van Dingenen, E. Vignati, J.Wilson, J. P. Putaud, J. H. Seinfeld and P. Adams, “Formation and Cycling of Aerosols in the Global Troposphere,” Atmospheric Environment, Vol. 34, No. 25, 2000, pp. 4215-4240. http://dx.doi.org/10.1016/S1352-2310(00)00239-9
 C. Arden Pope III, R. T. Burnett, M. J. Thun, E. E. Calle, D. Krewski, K. Ito and G. G. Thurston, “Lung Cancer, Cardiopulmonary Mortality, and Long-Term Exposure to Fine Particulate Air Pollution,” Journal of American Medical Association, Vol. 287, No. 9, 2002, pp. 1132-1141.
 J. Schwartz, “What Are People Dying of on High Air Pollution Days?” Environmental Research, Vol. 64, No. 1, 2002, pp. 26-35. http://dx.doi.org/10.1006/enrs.1994.1004
 G. Wang, H. Wang, Y. Yu, S. Gao, J. Feng, S. Gao and L. Wang, “Chemical Characterization of Water-Soluble Components of PM10 and PM2.5 Atmospheric Aerosols in Five Locations of Nanjing, China,” Atmospheric Environment, Vol. 37, No. 21, 2003, pp. 2893-2903.
 M. T. Cheng, Y. C. Lin, C. P. Chio, C. F. Wang and C. Y. Kuo, “Characteristics of Aerosols Collected in Central Taiwan during Asian Dust Event in Spring 2000,” Chemosphere, Vol. 61, No. 10, 2005, pp. 1439-1450.
 J. Yin and R. M. Harrison, “Pragmatic Mass Closure Study for PM1, PM2.5 and PM10 at Roadside, Urban Background and Rural Sites,” Atmospheric Environment, Vol. 42, No. 5, 2008, pp. 980-988.
 J. P. Putaud, R. Van Dingenen, A. Alastuey, H. Bauer, W. Birmili, J. Cyrys, H. Flentje, S. Fuzzi, R. Gehrig, H. C. Hansson, R. M. Harrison, H. Herrmann, R. Hitzenberger, C. Hüglin, A. M. Jones, A. Kasper-Giebl, G. Kiss, A. Kousa, T. A. J. Kuhlbusch, G. Loschau, W. Maenhaut, A. Molnar, T. Moreno, J. Pekkanen, C. Perrino, M. Pitz, H. Pusbaum, X. Querol, S. Rodriguez, I. Salma, J. Schwarz, J. Smolik, J. Scheneider, G. Spindler, H. Ten Brink, J. Tursic, M. Viana, A.Wiedensohler and F. Raes, “A European Aerosol Phenomenology-3: Physical and Chemical Characteristics of Particulate Matter from 60 Rural, Urban, and Kerbside Sites across Europe,” Atmospheric Environment, Vol. 44, No. 10, 2010, pp. 1308-1320.
 J. G. Watson, T. Zhu, J. C. Chow, J. Engelbrecht, E. M. Fujita and W. E. Wilson, “Receptor Modeling Application Framework for Particle Source Apportionment,” Chemosphere, Vol. 49, No. 9, 2002, pp. 1093-1136.
 J. G. Watson, L. Chen, J. C. Chow, D. H. Lowenthal and P. Doraiswamy, “Source Apportionment: Findings from the US Supersite Program,” Journal of the Air & Waste Management Association, Vol. 58, No. 2, 2008, pp. 265-288. http://dx.doi.org/10.3155/1047-32126.96.36.1995
 J. Watson and J. Chow, “Receptor Models for Air Quality Management,” EM, 2004, pp. 15-24.
 IUPAC, “Compendium of Chemical Terminology, 2nd Ed (the ‘Gold Book’),” Compiled by A. D. McNaught and A. Wilkinson, Blackwell Scientific Publications, Oxford, 1997.
 S. Marcazzan, G. Vaccaro and R. Vecchi, “Characterisation of PM10 and PM2.5 Particulate Matter in the Ambient air of Milan (Italy),” Atmospheric Environment, Vol. 35, No. 27, 2001, pp. 4639-4650.
 J. Herrera, “Costa Rica Metropolitan Area Emission Inventory 2007,” National University, Costa Rica, 2009, pp. 460-489.
 P. K. Hopke, “Receptor Modeling for Air Quality Management,” In: B. G. M. Vandeginste and O. M. Kvalheim, Eds., Data Handling in Science and Technology, Elsevier, Amsterdam, 1991.
 R. Henry, “UNMIX Version 2.4 Manual,” US Environmental Protection Agency, Research Triangle Park, 2001.
 R. L. Poirot, P. R. Wishinski, P. K. Hopke and A. V. Polissar, “Comparative Application of Multiple Receptor Methods to Identify Aerosol Sources in Northern Vermont,” Environmental Science and Technology, Vol. 35, No. 23, 2001, pp. 4622-4636.
 L. W. A. Chen, B. G. Doddridge, R. R. Dickerson, J. C. Chow and R. C. Henry, “Origins of Fine Aerosol Mass in the Baltimore-Washington Corridor: Implications from Observation, Factor Analysis, and Ensemble Air Parcel Back Trajectories,” Atmospheric Environment, Vol. 36, No. 28, 2002, pp. 4541-4554.
 H. Hellen, H. Hakola and T. Laurila, “Determination of Source Contribution of NMHC in Helsinki (60°N, 25°E) Using Chemical Mass Balance and the UNMIX Multivariate Receptor Models,” Atmospheric Environment, Vol. 37, No. 11, 2003, pp. 1413-1424.
 P. Paatero, “Least Square Formulation of Robust NonNegative Factor Analysis,” Chemometrics and Intelligent Laboratory, Vol. 37, No. 1, 1997, pp. 23-35.
 P. D. Hien, V. T. Bac and N. T. H. Thinh, “PMF Receptor Modelling of Fine and Coarse PM10 in Air Masses Governing Monsoon Conditions in Hanoi, Northern Vietnam,” Atmospheric Environment, Vol. 38, No. 2, 2004, pp. 189-201.
 E. Kim, T. V. Larson, P. K. Hopke, C. Slaughter, L. E. Sheppard and C. Claiborn, “Source Identification of PM2.5 in an Arid Northwest US City by Positive Matrix Factorization,” Atmospheric Research, Vol. 66, No. 4, 2003, pp. 291-305.
 F. Mazzei, A. Alessandro, F. Lucarelli, S. Nava, P. Prati, G. Valli and R. Vecchi, “Chracterization of Particulate Matter Sources in an Urban Environment,” Science of Total Environment, Vol. 401, No. 1-3, 2008, pp. 81-89.
 P. Paatero and P. K. Hopke, “Discarding or Downweighting High-Noise Variables in Factor Analytic Models,” Analytical Chimica Acta. Vol. 490, No. 1-2, 2003, pp. 277-289.
 P. Paatero, “User’s Guide for Positive Matrix Factorization Programs PMF2 and PMF3, Part 1: Tutorial,” US Environmental Protection Agency, 2000.
 L. M. Castro, C. A. Pio, R. M. Harrison and D. J. T. Smith, “Carbonaceous Aerosol in Urban and Rural European Atmospheres: Estimation of Secondary Organic Carbon Concentrations,” Atmospheric Environment, Vol. 33, No. 17, 1999, pp. 2771-2781.
 J. Herrera, J. F. Rojas, S. Rodriguez, V. H. Beita, D. Solorzano, A. Campos, B. Cardenas and D. G. Baumgardner, “Temporal and Spatial Variations in Organic and Elemental Carbon Concentrations in PM10/PM2.5 in the Metropolitan Area of Costa Rica, Central America,” Atmospheric Pollution Research, Vol. 4, 2013, pp. 53-63.
 C. Hueglin, R. Gehrig, U. Baltensperger, M. Gysel, C. Monn and H. Vonmont, “Chemical Characterisation of PM2.5, PM10 and Coarse Particles at Urban, Near-City and Rural Sites in Switzerland,” Atmospheric Environment, Vol. 39, No. 4, 2005, pp. 637-651.
 P. Warneck, “Chemistry of the Natural Atmosphere,” Wiley and Sons, Academy Press, 1987, p. 757.
 J. Sternbeck, A. Sjodin and K. Andréasson, “Metal Emissions from Road Traffic and the Influence of Resuspension: Results from Two Tunnel Studies,” Atmospheric Environment, Vol. 36, No. 30, 2002, pp. 4735-4744.
 J. H. Seinfeld and S. N. Pandis, “Atmospheric Chemistry and Physics from Air Pollution to Climate Change,” Wiley, New York, 1998, pp. 649-655.
 J. P. Putaud, F. Raes, R. Van Dingenen, E. Brüggemann, M. C. Facchini, S. Decesari, S. Fuzzi, R. Gehrig, C. Hüglin, P. Laj, G. Lorbeer, W. Maenhaut, N. Mihalopoulos, K. Müller, X. Querol and S. Rodriguez, “A European Aerosol Phenomenology-2: Chemical Characteristics of Particulate Matter at Kerbside, Urban, Rural and Background Sites in Europe,” Atmospheric Environment, Vol. 38, 2004, pp. 2579-2595.
 M. Zheng, L. G. Salmon, J. J. Schauer, L. Zeng, C. S. Kiang and Y. Zhang, “Seasonal Trends in PM2.5 Source Contributions in Beijing, China,” Atmospheric Environment, Vol. 39, No. 22, 2005, pp. 3967-3976.
 F. K. Duan, K. B. He, F. M. Yang, X. C. Yu, S. H. Cadle and T. Chan, “Concentrations and Chemical Characteristics of PM2.5 in Beijing, China: 2001-2002,” Science of Total Environment, Vol. 355, No. 1-3, 2006, pp. 264-275.
 S. H. Cadle, P. A. Mulawa, E. C. Hunsanger, K. E. Nelson, R. A. Ragazzi and R. Barrett, “Composition of LightDuty Motor Vehicle Exhaust Particulate Matter in the Denver, Colorado Area,” Environmental Science and Technology, Vol. 33, No. 14, 1999, pp. 2328-2339.