Polycyclic Aromatic Hydrocarbons and PM10, PM2.5, PM1.0 Particles in the Atmosphere over the Southern Baikal Region

The study presents the data on concentrations of polycyclic aromatic hydrocarbons (PAHs), coarse (PM 10 , PM 2.5 ) and submicron (PM 1.0 ) particles in the atmosphere over the southern Baikal region at two monitoring stations (urban (Irkutsk) and rural (Listvyanka village)) in 2019–2022. Seasonal dynamics and high correlations between their concentrations are revealed. It was found out that PAHs are mainly sorbed on coarse particles in the atmosphere over Irkutsk and on submicron particles in Listvyanka. The total concentration of 21 PAHs varied at the stations from 1–3 ng/m 3 in summer to 35–50 ng/m 3 in winter, with an average annual value approximately 20 ng/m 3 . High concentrations in all seasons were determined for fluoranthene, pyrene, benzo[b]fluoranthene, benzo[k]fluoranthene, and phenanthrene. The calculated equivalent of aerosol toxicity in the atmosphere over Irkutsk increased from summer to winter with a growing contribution of benzo[a]pyrene exceeding maximum permissible concentration (MPC) by 8 times. The mass concentration during the year varied from 13 to 180 g/m 3 for PM 10 , from 4 to 121 g/m 3 for PM 2.5 , from 4 to 118 g/m 3 for PM 1.0 . Exceeding the MPC for PM 2.5 by 1.1–3.4 times was recorded in Irkutsk from November to May. Diagnostic ratios of PAHs and the factor analysis identified the main sources of air pollution by this class of compounds over the southern Baikal region, which are combustion of coal, liquid fuel, and firewood, and also motor transport emissions.