Contamination by potentially toxic elements (PTE) is not periodically evaluated, given that the chemical analyses have a high cost. The ashes and combustion fumes give the ground a dark color, which could serve as a proxy indicator. In this study, a methodology was designed to prove the use of the color of urban dust as an indicator of contamination by PTE, and the most contaminated color was identified. 86 dust samples from Ensenada, Baja California were analyzed. The color of the samples was measured and the color indices (CI) were calculated using the RGB system. Nickel (Ni), Copper (Cu), Zinc (Zn), Lead (Pb), Rubidium (Rb), Vanadium (V), Strontium (Sr), and Yttrium (Y) were analyzed through x-ray fluorescence methods. The samples were grouped by color using the Munsell tables; the groups were validated with a discriminant analysis using the color indices. The multiple regressions indicated that there exists a relation between the CI and the PTE. The averages of the analyzed elements in the samples grouped by color were different (Kruskal-Wallis, P < 0.05). Gray dust contains higher concentrations of Pb, Cu, Zn and Ni. The color indices of urban dust can be considered a proxy methodology given their low cost, speed and reliability.