Characteristic Metal Marker of Non-exhaust PM10 Vehicular Emissions in Cebu City, Philippines

Non-exhaust vehicular emissions are becoming a focus of research due to their increasing contribution to air pollution and its health effects. The characterization of this emission using Fe, Cu, Mn, and Zn as possible metal markers and expression of metal ratios was tackled in this study. The metal concentrations in ambient air present as PM10 of Cebu Business Park (CBP) in Cebu City, Philippines were obtained from January–November 2016 and were characterized for trace metals. The filters were digested, and metal concentrations were analyzed using flame atomic spectroscopy via an external calibration method. The average concentration of Fe at 0.3975 μg/m3, Cu at 0.1191 μg/m3, Zn at 0.1228 μg/m3, and Mn at 0.0178 μg/m3. Subsequently, the metal concentrations were correlated with each other. The Fe and Zn presented a significant correlation with r = 0.927. Enrichment and roadside enrichment factors between the sampling site and the urban background revealed that the metals were from vehicular activity. The wear and tear of vehicular tires are identified as the source of the non-exhaust vehicular emission from the average slope of the regression line between Fe and Zn concentration in air filters is 30.1. It was also noted that the slope obtained during the wet season is approximately half that of the dry season. This study recommends further investigation using other metals to identify source fingerprints for future source apportionment studies to support the crafting of legislation to abate the non-exhaust component of vehicular emissions.