Environmental Assessment of Road Dust at Bus Stops in Villavicencio, Colombia

The accumulation of potentially toxic elements (PTEs) in road dust poses a significant risk to the environment and public health, especially in urban areas with high traffic density. However, few studies have assessed these risks in environments such as university bus stops, particularly in Colombia. The objective of this study was to assess the pollution levels and potential risks associated with lead (Pb), cadmium (Cd), copper (Cu), and zinc (Zn) in road dust collected at bus stops at Universidad de los Llanos, in Villavicencio, Colombia. Dust samples were collected from eight bus stops using a brush and tray over 1 m² areas, with five subsamples per site along 100-meter stretches. The samples were stored in polyethylene bags and homogenized using a 2.0-mm sieve. Concentrations of heavy metals (Pb, Cu, Zn, Cd) were determined by microwave-assisted acid digestion followed by Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) analysis. The mineralogical composition was analyzed through X-ray diffraction (XRD) using Cu Kα radiation (λ = 1.54060 Å) in a range from 2° to 70°. The levels of all elements exceeded the background values for the area. Pb concentrations ranged from 15.0 to 44.6 mg kg⁻¹, Cd levels ranged from 0.6 to 1.2 mg kg⁻¹, Cu levels ranged from 17.6 to 115.6 mg kg⁻¹, and Zn levels ranged from 69.8 to 519.6 mg kg⁻¹. The geoaccumulation index and the integrated pollution index indicated significant contamination with copper and zinc being the most abundant elements. The ecological risk assessment revealed cadmium as the greatest potential threat. The results underscore the need to implement stricter environmental controls and urban development strategies to reduce PTEs exposure in areas near public transportation. The findings of this study provide key information for policymaking aimed at improving air quality and soil management in urban settings.