Ecological risk assessment of heavy metals in urban dust in Iran: A systematic review and meta-analysis.

Background: Heavy metals in street dust are one of the most important sources of pollutants in urban areas. This urban dust can be caused by industrial activities, traffic, erosion of buildings, and fossil fuels. The aim of this systematic review is to evaluate the ecological risk of heavy metals in the dust of Iran's provinces.

Methods: This study was conducted in February 2023 in order to investigate the environmental risks associated with heavy metals associated with dust particles in Iran. The present study was conducted based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Finally, 9 studies were extracted from the search databases.

Results: The ecological risk of heavy metals in the present study was as follows: Cd (258.26؛ CI: 83.53, 433) >Pb (52.58؛ CI: 37.15, 68.02) >Cu (24.44؛ CI: 16.74, 32.14)>Ni (14.75؛ CI: 12.68, 16.82)>As (13.53؛ CI: 10.20, 16.85)>Zn (6.32؛ CI: 3.76, 8.87)>V (3.18؛ CI: 2.65, 3.72)>Cr (2.73؛ CI: 2.19, 3.27)>Co (1.94؛ CI: 1.13, 2.74). The mean ranking of the studied Pb ecological risk is as follows: Shiraz.> Tehran > Ahvaz > Ilam > Abadan > Dezful.

Conclusion: The ecological risk potential of Cd in Tehran was also much higher than the standard. Therefore, Tehran was the most polluted city studied in terms of the ecological risk potential of Cd (1611.41؛ CI: 1605.98, 1616.84) and Pb (86.54؛ CI: 71.46, 101.62). The average concentration as well as the ecological risk of Cr, Co, and V metals were lower than the standard. Therefore, controlling the sources of heavy metal emissions (especially lead and cadmium) is highly recommended.