Contents lists available at ScienceDirect Journal of Environmental Management journal homepage: www.elsevier.com/locate/jenvman Research article Determining of risk areas due to exposure to heavy metals in the Toluca Valley using epiphytic mosses as a biomonitor P. Ávila-Pérez a , H.B. Ortiz-Oliveros b,d,∗ , G. Zarazúa-Ortega b , S. Tejeda-Vega c , A. Villalva d , R. Sánchez-Muñoz c a Departamento de Posgrado, Instituto Tecnológico de Toluca, Ex rancho la Virgen S/N, C.P. 50120, Metepec, Mexico b Dirección de Investigación Tecnológica, Instituto Nacional de Investigaciones Nucleares, A. P. 18-1027, Col. Escandón, Delegación Miguel Hidalgo, C. P. 11801, México, D. F., Mexico c Dirección de Investigación Científica, Instituto Nacional de Investigaciones Nucleares, A. P. 18-1027, Col. Escandón, Delegación Miguel Hidalgo, C. P. 11801, México, D. F., Mexico d Universidad Autónoma del Estado de México, Toluca, México, Instituto Literario 100, CP 50000, Toluca, Estado de México, Mexico ARTICLE INFO Keywords: Bioindicators Biomonitor Geostatistical analysis GIS Heavy metals Risk area ABSTRACT The work aim is to identify the risk areas by exposure to Cr, Cu, Pb and Zn in the Metropolitan Zone of Toluca Valley (MZTV) using the mosses Fabriona cilaris and Leskea angustata as a biomonitors, geostatistical inter- polation and multi-criteria evaluation by analytical hierarchy process. The results from the estimation of the enrichment factors (EF) showed that Pb is the heavy metal with the highest values, followed by the Zn, Cu and Cr. The EF obtained for all heavy metals show that there is a moderate to high anthropogenic enrichment. The above indicates that in the MZTV there are emission sources that contribute (significantly) in the amount of Cr, Cu, Pb and Zn accumulated in the biomonitor. Combustion processes, vehicle emissions, biomass burning, brick kiln emissions, agricultural and livestock activities, manufacturing industry and re-deposition by the action of the wind, were identified as the main heavy metals sources in the MZTV. Risk maps showed the high and medium risk areas are located in sites with poor urban vegetation coverage and close to highways and industrial parks. Low risk areas are located in sites with high urban vegetation coverage. The method used for identifying risk areas is a rapid and low-cost evaluation tool can allow local government environmental agencies to define public policies on air pollution control. 1. Introduction The accelerated growth of the world population, particularly in developing countries, has accelerated the urbanization and in- dustrialization processes of metropolitan areas around the entire planet. These processes generate several pressures in the environment, the most important being air pollution due to the burning of fossil fuels and various industrial activities. Pollutants such as greenhouse gases, toxic substances (benzene, toluene, xylene), particulate matter and heavy metals, are released in- discriminately in the air with serious consequences for the environment and people. Heavy metals are important components of air pollution due to their high toxicity, easy dispersion, but above all because of their persistence and bioaccumulation in the ecosystem (Koz et al., 2012; Turkyilmaz et al., 2018a), such characteristics that increase the health risks for the inhabitants of urban centers. For example, several studies have shown that the exposure to high levels of heavy metals concentration increases the risk of adverse effects on human health by damage to central and peripheral nervous system, lungs, kidneys and liver, or even death (Shaban et al., 2016; Zeng et al., 2016). A long exposure to low concentrations of heavy metals is related to symptoms such as nose and throat irritation, cough, dyspnea and asthma (Koedrith et al., 2013). Studies such as Zeng et al. (2016) in- dicate the presence of heavy metals such as Pb, Cd and the other heavy metals in particulate matter (2.5 μm) may be related with the increase in respiratory symptoms such as cough, phlegm and dyspnea, as well as asthma in children. These health effects demonstrate the importance of monitoring heavy metals in urban centers. Exposed population health studies and identification of risk areas can be limited due to the high costs of environmental monitoring and the complexity of analytical https://doi.org/10.1016/j.jenvman.2019.04.018 Received 16 November 2018; Received in revised form 2 March 2019; Accepted 7 April 2019 ∗ Corresponding author. Dirección de Investigación Tecnológica, Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, Col. Escandón, Delegación Miguel Hidalgo, C.P. 11801, México, D.F., México. E-mail address: huemantzin.ortiz@inin.gob.mx (H.B. Ortiz-Oliveros). Journal of Environmental Management 241 (2019) 138–148 Available online 15 April 2019 0301-4797/ © 2019 Elsevier Ltd. All rights reserved. T