Atmospheric particulate matter (PM) samples were collected in Riyadh, Saudi Arabia, to assess air quality, quantify, heavy metal concentrations, and evaluate related ecological and health risks. This study’s uniqueness stems from its focused and detailed analysis of PM pollution in Riyadh, including an extensive assessment of heavy metal concentrations across different PM sizes by applying diverse pollution and health indices. This brings to light critical health and ecological issues and provides foundation for targeted pollution control efforts in the region. The study focused on two PM size fractions, PM2.5 and PM10 and analyzed the presence of heavy metals, including iron (Fe), nickel (Ni), chromium (Cr), zinc (Zn), cobalt (Co), copper (Cu), silver (Ag), arsenic (As), cadmium (Cd), and lead (Pb), using inductively coupled plasma emission spectrometry. Results showed significantly higher levels of PM10 (223.12 ± 66.12 µg/m3) compared to PM2.5 (35.49 ± 9.63 µg/m3), suggesting that local dust is likely a primary source. Air quality varied from moderate to unhealthy, with PM10 posing substantial risks. Heavy metal concentrations in PM2.5 followed the order Fe (13.14 ± 11.66 ng/m3) > As (2.87 ± 2.08 ng/m3) > Cu (0.71 ± 0.51 ng/m3) > Zn (0.66 ± 0.46 ng/m3) > Cr 0.50 ± 0.23 ng/m3) > Pb (0.14 ± 0.10 ng/m3) > Ni (0.03 ± 0.04 ng/m3) > Cd (0.004 ± 0.002 ng/m3) > Ag (0.003 ± 0.003 ng/m3) > Co (0.002 ± 0.004 ng/m3). In PM10, they followed the order Fe (743.18 ± 593.91 ng/m3) > As (20.12 ± 13.03 ng/m3) > Cu (10.97 ± 4.66 ng/m3) > Zn (9.06 ± 5.50 ng/m3) > Cr (37.5 ± 2.70 ng/m3) > Ni (1.72 ± 01.54 ng/m3) > Pb (1.11 ± 0.64 ng/m3) > Co (0.25 ± 0.28 ng/m3) > Ag (0.10 ± 0.26 ng/m3) > Cd (0.04 ± 0.02 ng/m3). Enrichment factor analysis revealed elevated levels for the metals Cu, Zn, As, Ag, Cd, and Pb. Pollution indices indicated various contamination levels, with Ag and As showing particularly high contamination and ecological risks. The study highlighted significant health concerns, especially from As, which poses a substantial long-term carcinogenic threat. The findings emphasize the urgent need to reduce hazardous metal levels in Riyadh’s air, especially with high child exposure.
