Urban Street Dust as a Mirror of Industrial Identity: A Comparative Analysis of Metal Pollution Profiles and Health Risks) Caseud Study: Borujerd City, Iran)

Urban street dust serves as a critical reservoir for toxic potentially toxic elements, posing significant environmental and public health risks—particularly in industrializing regions of the Global South. While numerous studies have assessed metal pollution in individual cities, a crossregional synthesis linking contamination profiles to socio-industrial contexts remains lacking. To address this gap, we conducted a systematic review and comparative meta-analysis of peerreviewed studies (2015–2025) from urban centers across Iran and South Asia, integrating new empirical data from Borujerd City, Iran—a representative case of small industrial cities in semiarid zones. Our analysis reveals a striking regional divergence: Iranian cities consistently exhibit arsenic (As)-dominated pollution, with hazard quotients (HQ) for children reaching 17.05 in Borujerd, far exceeding safe thresholds. In contrast, South Asian cities (e.g., Gazipur, Bangladesh) show rising contamination from technology-critical elements (Bi, Ga, In) linked to e-waste and electric mobility. Source apportionment across the region identifies industrial gas emissions (29.6% in Borujerd) and traffic-related activities as dominant contributors, though their chemical fingerprints differ markedly. While carcinogenic risks remain below the U.S. EPA threshold (10⁻⁶), non-carcinogenic risks, especially from As-demand urgent intervention. We propose a dual-track policy framework: (i) strict emission controls on As-laden industrial gases in Iran, and (ii) e-waste recycling regulations to curb emerging metal leakage in South Asia. This study provides a scalable model for context-sensitive urban dust management that balances industrial development with public health protection.