Surface Ozone in the Atmosphere of Moscow during the COVID-19 Pandemic

We present the results from monitoring surface ozone in the atmosphere of Moscow in 2020 and 2021 under lockdown conditions linked to the COVID-19 pandemic. These two years significantly differed in meteorological conditions and the level of anthropogenic environmental load. A level of surface O(3) concentrations, relatively low for a megalopolis, was observed in Moscow in 2020. The annual average concentration was 28 μg/m(3), and the annual maximal concentration was 185 μg/m(3). That was due to relatively cool summer with the low content of pollutants in atmospheric air. Intense heat waves were observed in the megalopolis during summer 2021 under the conditions of a blocking anticyclone, when the daytime temperatures rose to 35°C. Combined with higher atmospheric air pollution, this resulted in unusually high O(3) concentrations. The annual average concentration was 48 μg/m(3), and the annual maximal concentration was 482 μg/m(3).