Metal-bearing airborne particles from mining activities: A review on their characteristics, impacts and research perspectives

The presence of various contaminants in airborne dusts from metal mining sites poses obvious risks to human health and the environment. Yet, few studies have thoroughly investigated the properties of airborne particles in terms of their morphology, size distribution and chemical composition, that are associated with health effects around mining activities. This review presents the most recent knowledge on the sources, physicochemical characteristics, and health and environmental risks associated with airborne dusts from various mining and smelting operations. The literature reviewed found only one research on atmospheric dust associated with hydrometallurgical plants compared to a larger number of pyrometallurgical processes/smelters studies. In addition, there are relatively few works comparing the distribution of metals between the fine and coarse size fractions around mining sites. Our analysis suggests that (i) exposure pathways of metal(loid)s to the human body are defined by linking concentration data in human biosamples and contaminated samples such as soils, drinking water and food, and (ii) chitosan and its derivatives may serve as an environmentally friendly and cost-effective method for soil remediation, with removal rates for metal(loid)s around 70-95 % at pH 6-8, and as dust suppressants for unpaved roads around mining sites. The specific limit values for PM and metal(loid)s at mining sites are not well documented. Despite the health risks associated with fine particles around mining areas, regulations have tended to focus on coarse particles. While some air quality agencies have issued regulations for occupational health and safety, there is no global alignment or common regulatory framework for enforcement. Future research priorities should focus on investigating PM and secondary inorganic aerosols associated with hydrometallurgical processes and dust monitoring, using online metal(loid)s analysers to identify the driving parameters in the deposition and resuspension process.