Color as a New Proxy Technique for the Identification of Road Dust Samples Contaminated with Potentially Toxic Elements: The Case of Mérida, Yucatán, México

Yameli Aguilar,Rudy Trejo-Tzab,Patricia Quintana,Francisco Bautista,Daniel Aguilar,Roberto Chan-Te,Avto Goguitchaichvili

doi:10.3390/atmos12040483

Abstract

The design of proxy techniques is an innovative tool to monitor the potentially toxic elements of pollution in road dust. This study evaluated the use of road dust color as a proxy methodology to identify samples contaminated with presumably contaminating elements. FRX determined the concentrations of Fe, Ti, Rb, Sr, Y, Cu, Zn, and Pb in eighty-five road dust samples. The appliance of the RGB system and the Munsell color cards identified five color groups of road dust samples. The discriminant analysis validated these groups by colorimetric indices and presumably contaminating elements. The “very dark gray” color of road dust contains the highest concentrations of Pb, Cu, Zn, and Y. The redness and saturation rates showed high correlations with presumably contaminating elements in “dark gray” and “very dark gray” color samples. The color of road dust, as a proxy technique, allows identifying samples contaminated with presumably contaminating elements.

Highlights

IntroductionThe World Health Organization [1] stated that around 6 million people living in cities die from environmental pollution, of which pollutants are presumably part of the problem because they can adhere to plant leaves and trees [2,3], on the soil [2,4,5], and in road dust [3,6]
The very dark gray and greyish brown color samples reached 87.5% and 77.5% of correctly assigned cases, respectively (Table 2)
The five colors of road dust samples from the city of Mérida, Mexico, can be used as a guide to discard or select samples contaminated with presumably contaminating elements and oxides of Ti and Fe

Summary

Introduction

The World Health Organization [1] stated that around 6 million people living in cities die from environmental pollution, of which pollutants are presumably part of the problem because they can adhere to plant leaves and trees [2,3], on the soil [2,4,5], and in road dust [3,6]. The prolonged exposure to particles with presumably contaminating elements and with sizes of 10 μm or smaller, can lead them to enter the respiratory system, deposit in the trachea and lungs, reach the bloodstream, and generate various health problems, including being precursors of cancer [11]

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Conclusion