Exposure to airborne pollutants in urban and rural areas: levels of metals and microorganisms in PM10 and gaseous pollutants in ambient air

Assessing air quality is a crucial health concern due to an increase in human activities. This study examined the concentrations of heavy metals (HMs), harmful gaseous compounds and microbial load in rural and urban regions’ outdoor atmospheric air. Eighty atmospheric samples were sampled randomly from 16 locations (8 locations each from urban and rural areas) in southern Nigeria; and their HMs, gaseous compounds (SO₂, CO, NO₂, VOC, CH₄ and NH₃), and microbial levels were determined in accordance with standard procedures. The results revealed that the pollutants level in air sampled from urban areas, was significantly higher than the level recorded at the rural areas (p < 0.05). It was noted that Fe had the highest concentration (mean ∼ 2.448 µg/m³) and mercury (Hg) had the lowest concentration (mean ∼ 7.0 × 10^− 3 µg/m³). The heavy metals concentration in the outdoor PM₁₀ followed this increasing pattern: Hg < Cd < Ni < As < Co < Cr < Pb < Zn < Fe; and the gaseous components - SO₂, CO, NO₂, VOC, CH₄ and NH₃ – levels in the atmospheric samples were 15.13 ± 10.19, 177.48 ± 114.81, 11.65 ± 4.85, 3544.50 ± 1752.70, 2048.00 ± 978.35 and 855.98 ± 323.73, respectively. Likewise, these microorganisms, Escherichia coli, Salmonella, Staphylococcus aurius, Aspergillus spp and Penicillium spp were isolated from the outdoor atmospheric samples. The presence of HMs, gaseous compound and harmful microorganisms in outdoor PM₁₀ highlights the importance of minimizing atmospheric emissions and maintaining good hygiene practices to reduce the health risk associated with exposure to these pollutants. Therefore, town planners and relevant professionals should device means of decongesting the traffic volume in urban areas, and installing adequate waste management systems.