Seasonal and Spatial Variability of PM_2.5 Concentration, and Associated Metal(loid) Content in the Toluca Valley, Mexico

This study provides evidence of the seasonal and spatial variation of metal(lloid)s in particulate matter minor to 2.5 microns (PM_2.5) in the Toluca Valley Metropolitan Area (TVMA), the fifth largest urban center in Mexico. Four sites were sampled between 2013 and 2014, which included urban and industrial areas, in the dry-cold (November-February) and dry-hot (March-May) seasons; PM_2.5 was collected using high- and medium-volume samplers. Metal(lloid) concentrations in PM_2.5 were analyzed using inductively coupled plasma‒mass spectrometry (ICP‒MS). The highest 24-hour PM_2.5 concentration in the northern area was observed, and the PM_2.5 concentrations were independent of the season. Five metal(lloid)s with a recovery percentage above 80% were considered to be reported (Co, Cr, Cu, Mn, and Sb). The maximum concentrations of metal(lloid)s were observed during the dry-cold season, and concentrations were up to one hundred or thousand fold with respect to the dry-hot season. The 24-hour PM_2.5 and metal(lloid) concentrations exceeded national and international guidelines to protect population health.