Impacts of the COVID-19 Lockdown Measures on the 2020 Columnar and Surface Air Pollution Parameters over South-Eastern Italy

Abstract

The combined use of Lecce-University AERONET-photometer measurements and PM2.5, PM10, NO2, CO, and SO2 concentrations from different sites of Apulia-Region Air-Quality Agency represents the peculiarity of this study, which evaluates the impact of COVID-19 lockdown (LD) measures on aerosol and gaseous pollutants. Monthly-averaged columnar and surface parameters of the 2020-year were compared with corresponding monthly parameters of the ref-year obtained by averaging 2017, 2018, and 2019 measurements in order to evaluate LD measure impacts by Average Percent Departure (APD%). Photometer measurements showed that LD measures were likely responsible for the decrease in Aerosol Optical Depth (AOD). The APD% estimated between the 2020- and ref-year AOD (at 440 nm) was characterized by negative values from June to August, reaching the smallest mean value (−46%) in June. Moreover, the columnar aerosol load appeared less affected by continental urban/industrial particles than previous years in the summer of 2020. The PM-concentration-APD% calculated at ten sites was characterized by monthly trends similar to those of AOD-APD%. PM-APD% values varied from site to site and smaller values (up to −57% in June) were on average detected at urban/suburban sites than at background sites (up to −37%). The impact of LD measures on gaseous pollutants was observed from the onset of LD.

Footprint of the 2020 COVID-19 Lockdown on Column-Integrated Aerosol Parameters in Spain

“…These results indicate that the column aerosol was not significantly affected immediately after the introduction of the restrictions but rather in a later period after the removal of the most restrictive measures in most European countries. Similar behaviour was observed at several sites in south-eastern Italy [45] and in Paris [46]. This fact could be due to the fact that most atmospheric particles are not directly emitted into the atmosphere, as is the case for gaseous pollutants [68,69].…”

“…Regarding the studies of column aerosol, the AERONET measurements showed that, while AOD decreased in Italy [45] during the lockdown, it increased in France [46]. These measurements were in line with MODIS satellite measurements, which observed a significant reduction in AOD in Poland [47] and most areas in Europe, except for its western part, where it increased [10,11].…”

Source Apportionment of PM10 as a Tool for Environmental Sustainability in Three School Districts of Lecce (Apulia)

“…The PM investigation in the city of Lecce has been carried out in several studies [9][10][11][12], where primary and secondary contributions to PM by means of bulk chemical analyses were carried out. Bulk chemical analyses provide averaged information on the composition of the PM, and it is possible to trace the emission sources through statistical approaches by considering the correlations between the analytes present in the sample.…”