Spatial distribution and Health Risk Evaluations of Toxic Metals in Indoor Aerosols from Microenvironments in Universities.

The present study was carried out to understand the spatial distribution of toxic heavy metals in aerosols from indoor environments in universities, elucidate the potential health implications and provide strategies for improved indoor air quality. Aerosols were characterized using SEM, Particle analyzer and BET Surface Area analyzer and quantification of heavy metals was carried out with ICP-MS. Characterization analysis indicates the samples are mainly made of elemental carbon while particle size of aerosols from the three indoor environments are consistent at ≈ 3.5 μm. For the carcinogenic metals in aerosols, Ni was the highest (Ni > Cr >Pb>As), while for non-carcinogenic metals, Ti was the highest (Ti >Zn >Mn> V >Cu > Co >Sb). The As and Pb concentrations detected were beyond the international crustal values. For alkali and alkali-earth metals, Mg consistently exhibited the highest concentrations across all universities, with a peak value of 669.5 μg/g detected aerosols from the library in University A. From cancer risks analysis, both adults and children face potential risk of having cancer from exposure to a cocktail of these toxic metals in aerosols especiallyfrom offices and laboratories. We observe that Cr is the main contributor to cancer risk and Mn with Sb to non-carcinogenic risks. Enrichment Factor calculations show that Zn and Sb in aerosols from the three indoor environments were significantly enriched in universities established in urban and metropolitan cities. Hierarchical Cluster Analysis of the Principal Component Analysis indicate a mix of anthropogenic and natural activities as being responsible for the levels of these toxic metals in the indoor environments.