Correlation analysis of the variability of NO2 and PM tropospheric concentrations within the Greater Salento (Italy) before, during and after the COVID-19 lockdown

The period of lockdown, which occurred in many nations as a result of the COVID-19 pandemic, represented, for scholars, who deal with the complex dynamics connected to emissions and concentrations of atmospheric pollutants, an excellent opportunity to deepen their studies However, to date, scientific papers, relating to correlation studies between the spatial and temporal variations of thue main pollutants present in our cities (among all, NO2 and particulates), during the long and atypical period of the almost total block of vehicular traffic and many productive activities during pandemic peak, are still very few This analysis focuses on the Greater Salento region (Italy) and aims to monitor the changes, and the related interrelationships, of the tropospheric concentrations of NO2, PM2 5 and PM10, elaborating the overall data of average daily concentrations of these pollutants as recorded by the ARPA-Puglia ground-based monitoring stations Nitrogen dioxides and PM emissions are notoriously related to vehicular traffic exhausts and, in general, to fossil fuel combustion processes This analyzed Italian territory is very unusual because there are two provinces with large industrial settlements, Taranto, with the steel area of ex-ILVA, and Brindisi, with petrochemical and thermoelectric power plants, which enclose a territory, the province of Lecce, free of any industrial plants of such sizes and impacts From the results of this study, in addition to confirming the obvious and overall decrease of NO2 concentrations during and after the lockdown period, interesting and distinctive local correlations of the concentrations variability of these pollutants have also emerged In fact, the conclusions of this paper are so significant as to allow broader considerations regarding other similar international areas, regarding, i e , the ineffectiveness of government containment local measures concerning the tropospheric pollution of our cities