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The results of an analysis of changes in the atmospheric air quality in Moscow during the lockdown period and the decline in business activity caused by the COVID-19 coronavirus pandemic are presented. The observed changes in urban air pollution represent a unique experiment to assess the impact of various anthropogenic influences on the composition of atmospheric air. The influence of weather factors and transport activity on the level of pollution in the spring of 2020 is considered. The level of the main pollutants in the atmosphere decreased by 30–50% during the period of lockdown, and a different type of changes was revealed near highways and in residential areas. This article discusses the possibilities and difficulties of using a “unique experiment” on a sharp decrease in traffic intensity in large cities to determine the contribution of various branches of the urban economy (transport, energy, industry, waste processing) to the total air pollution in large cities.

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Information on the ozone concentration in the surface air and troposphere in the first half of 2020 is presented. The data were acquired at 13 stations in different Russian regions; vertical distributions were obtained with the use of an aircraft laboratory. The excess over the Russian Federation hygienic standards is assessed; the daily average ozone concentration is found to be regularly higher the maximum permissible concentrations at most stations. At some stations, there are features the seasonal variations in the ozone concentration in the period under study different from previous years.