Heavy metals levels in road dust from Muscat, Oman: relationship with traffic volumes, and ecological and health risk assessments

Dust samples from roads classified based on traffic volumes (low, medium and high traffic) were collected from Muscat, Oman, and then analyzed for a dozen heavy metals. Their contents varied widely with mercury and iron, having the lowest and highest concentrations (0.59–0.80 and 406.10–429.00 ppm, respectively). Contrary to most metals detected, mercury and arsenic did not only exhibit increasing trends from low to high categories, but they also were significantly correlated to each other and traffic volumes, suggesting that both might originate from vehicular emissions. While the calculations revealed that the potential ecological risk index (RI) for selected metals in the dust samples was at a considerable level, the hazard index (HI) was within the safe threshold value (HI < 1). Overall, our findings imply minor prejudicial health risks to the general public nevertheless, children would be relatively more vulnerable to the impact of metals associated with dust.