A Characterization and Cell Toxicity Assessment of Particulate Pollutants from Road Traffic Sites in Kano State, Nigeria

Emerging African countries are characterized by explosive population growth and urbanization,
which threaten environmental sustainability. This study comparatively characterized
ambient aerosols and assessed cytotoxicity to facilitate improving health and environmental policy.
Twenty-four air samples were collected at high and low-density traffic sites in Kano State using polysulfone
and stainless steel filters attached to an automated pump. The physico-chemical properties
of particulate matter were determined using scanning electron microscopy and energy dispersive
X-ray analysis (SEM-EDX). In vitro, their potential toxicity was assessed using macrophages and cell
fixation with staining. Results showed 51.7% of particles as PM 2.5, with the highest particle concentration
in mixed sites (urban and industrial). Particle classification into four groups by elemental
composition and structure showed: sand particles (Si, Al, Fe, Ca, Mg, K, Na, Mo, Sr, Zr) 30–51%;
other fibers 0–3%; other particles (Si, Fe, S, Mo, Zn, and other metals) 22–40%; and silicone-based
fibres 23–34%. The abundant elements are: Si, Al, Ca, Ce, Ti, Fe, Cl, Pb, and Mn. The lowest viability
on cytotoxicity assessment was recorded in mixed site M2. The majority of households were located
within 50 m of air sampling sites. Proximity to traffic sites worsens health, as evidenced in cytotoxicity
findings. We recommend improved urban planning and intensification of emissions control.