PM2.5, black carbon and exposure risk from vehicle traffic: exploratory insights from continuous monitoring and particle characterization

Abstract

The expansion of cities, population growth, and the increasing vehicle fleet have intensified challenges in urban mobility, contributing to deteriorating air quality and heightened health risks, particularly in rapidly urbanizing regions of Latin America. This study continuously monitored fine particulate matter (PM_2.5) and black carbon (BC) at high-traffic (HT) and urban background (UB) sites in Córdoba, Argentina, to assess their temporal variability and relationships with traffic dynamics. Individual particle morphology and chemical composition were analyzed to identify emission sources, and health risks related to BC exposure were estimated. Pollutant concentrations were consistently higher at HT sites, with BC-related carcinogenic risk exceeding international safety thresholds; however, given the relatively short monitoring period (15 days per site), these estimates should be interpreted as exploratory. Particle analysis revealed spherical particles and carbon-rich aggregates linked to incomplete fossil fuel combustion across all sites. Beyond direct traffic emissions, the study identified environmental exposure stratification within the city, with suburban and peripheral areas experiencing nighttime BC peaks from biomass burning associated with domestic heating, waste burning, and wildfires. The detection of compact soot aggregates suggests the long-range transport of aged biomass particles into the urban core. This study represents the first continuous and automated BC monitoring in Córdoba, integrating real-time measurements with particle-level morphological and chemical characterization. The combined assessment of source attribution, traffic dynamics, health risk, and particle microstructure provides new insights into pollution dynamics and exposure inequalities, supporting the development of more equitable and sustainable urban planning and health policies.