Road dust pollution of Cd, Cu, Ni, Pb and Zn along Islamabad Expressway, Pakistan

Islamabad Expressway is one of the busiest roads in the capital of Pakistan. For the assessment of heavy metal pollution level in dust generated on the Expressway, 13 samples of dust were collected from various places around the highway and four samples of soil were obtained from the undisturbed green land in Islamabad. The samples were analyzed for five heavy metals using FAAS (flame atomic absorption spectrometry). The average concentration values of the metals Cd, Cu, Ni, Pb and Zn were found to be 5 ± 1, 52 ± 18, 23 ± 6, 104 ± 29 and 116 ± 35 mg kg- 1 respectively, which were generally lower than the values cited in literature. The inter-elemental correlation of Cu and Pb indicated that they belonged to common anthropogenic sources. The pollution level was estimated based on the geoaccumulation index (Igeo), the pollution index (PI), and the integrated pollution index (IPI). The values of IPI were in the following order: Cu > Pb > Zn > Cd > Ni. All the indices for the metals under consideration were either low or corresponded to middle level of pollution. The pollution level is expected to increase due to rapid urbanization of the area. Some protective measures have therefore been proposed.