Impact of lockdown on air quality in Belgrade during COVID-19 pandemic

The Environmental Protection Agency of the Republic of Serbia continuously monitors and collects air quality parameters at numerous measuring points throughout the country. The results revealed that the levels of air pollution recorded during the lockdown differed from those recorded during the same period the previous years. In this paper, we examined pollutant concentration trends in 2020 and a few previous years to determine the underlying causes of these trends. Pollutants are measured at five stations in Belgrade from the beginning of March to the end of July between 2015 and 2020. Because no hourly data were available, nitrogen dioxide, sulphur dioxide, and suspended particles PM10 and PM2.5 are average daily values, whereas carbon monoxide and ozone are daily 8-hour maximums. Concentrations were compared and averaged only when data for the same period over time was available, i.e. when comparing 2020 to previous years. The results were compared to the annual and daily limit values (for ozone and carbon monoxide 8h maximums, respectively), as well as the variations in concentrations over time. The goal of calculating and displaying these values is to specifically identify a change in air pollution during the COVID-19 virus pandemic isolation period. In general, for Belgrade in 2020, NO2 concentrations are lower at four stations; PM2.5 concentrations are lower at two stations; PM10 concentrations are higher at one station and lower at another; and SO2 concentrations are higher than in previous years (2015-2019).