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.