Polycyclic Aromatic Hydrocarbons in Atmospheric PM2.5 and PM10 of Riyadh City, Saudi Arabia: Levels, Temporal Variation, and Health Impacts

<b>Background:</b> Polycyclic aromatic hydrocarbons (PAHs) in atmospheric particulate matter (PM) are high in Saudi cities due to industry and traffic, often exceeding safety limits. This study assesses PM_2.5 and PM₁₀ and health risks in Riyadh's desert environment. <b>Method:</b> High-purity chemicals and PAH standards were used. Air samples were collected at King Saud University, extracted, cleaned, and analyzed by GC-MS. QA/QC ensured accuracy, with RSDs of 4.6-7.9%. <b>Results:</b> Seasonal temperature shifts in Riyadh influence PM and PAH levels. Higher summer temperatures raise PM/PAH, posing health risks, especially via inhalation. Winter favors PAH accumulation on particles. <b>Conclusions:</b> Seasonal temperature shifts significantly affect PM_2.5, PM₁₀, and PAH levels in Riyadh, with summer posing the highest health risks. Inhalation is the main exposure route, especially for PM_2.5.