The impact of the physical state of the atmosphere on extreme air pollution from transport and industry in St. Petersburg

The article analyzes emissions of substances polluting the atmosphere of St. Petersburg from the transport and industrial complex and the practice of monitoring their impact on the population under an extremely hazardous combination of synoptic-meteorological and logistical factors. In 2012-2023, the vehicle fleet increased from 1,760,955 to 2,053,333, while emissions from it decreased by 3 times: from 419.3 to 140.6 thousand tons. Emissions from industry changed little: from 68.9 (2012) - 83.9 (2018) to 66.7 thousand tons (2023). By 2024, motor transport accounted for 67.8% of emissions into the atmosphere. The abundance of precipitation and powerful winds typical for the St. Petersburg region, together with the renewal of the vehicle fleet, contributed to a favorable environmental situation: for current pollutants, concentrations, on average, did not exceed the LTCMS. But, in short periods of «air stagnation» (1-3 days and a repeatability of 5.1% in 2023), local concentrations of NO2 reach 4-7 LTCMS, PM2.5-10, - 2-3 LTCMS. Scientific and methodological approaches to monitoring such dangerous situations, substantiated by the author, are implemented in Russian and international documents.