Resumen:
"Exposure to iron-rich particulate matter (PM) has been associated with increased risks of cardiovascular, respiratory,and neurological diseases, underscoring the need for robust tools to characterize pollutant sources and properties inindustrial urban environments. Environmental magnetism provides a rapid and sensitive approach to identify iron-bearing phases and constrain their grain size distribution and oxidation state.
Particulate matter was investigated in Volta Redonda city (Southeastern Brazil), a steel-producing city historicallylinked to Companhia Siderúrgica Nacional. Samples were collected from public trash cans, bus shelters, and roadsidesurfaces at distances up to 3 km from the steelworks. Magnetic susceptibility, anhysteretic and isothermal remanentmagnetizations, hysteresis loops, first-order reversal curves, and low-temperature experiments were conducted todetermine magnetic concentration, mineralogy, and domain state.
All samples exhibit a consistent magnetic assemblage dominated by hematite, but also stoichiometric and partiallyoxidized magnetite. The low-coercivity fraction spans superparamagnetic (few nm), single-domain, vortex/pseudo-single-domain, and multidomain grains (few microns). No statistically significant differences were detected amongsample types or as a function of distance, indicating a spatially pervasive iron oxide source across the study area.
These results demonstrate the utility of magnetic parameters for tracing industrial emissions and provide quantitativesupport for environmental monitoring and risk assessment in steel-producing regions."
