EFFECT OF COVID-19 LOCKDOWN ON AIR QUALITY IN URBAN AND SUBURBAN AREAS OF EXTREMADURA, SOUTHWEST SPAIN: A CASE STUDY IN USUALLY LOW POLLUTED AREAS

Lockdown measures were established in Spain from 14 th March 2020, to flatten the pandemic curve of coronavirus disease (COVID-19). The increasingly stringent implementation of these measures has made it possible to assess the effect of anthropogenic activities on the most relevant air pollutants present in ambient air. Whereas most published reports focus on highly polluted urban areas, the present work aims to quantify variations in the levels of NO 2 , O 3 and BTX (benzene, toluene and xylene) due to the COVID-19 lockdown in usually low polluted urban and suburban areas within Extremadura (Spain). Compared to the reference period from 2010 to 2019, significant reductions in NO 2 levels occurred in the suburban stations of Badajoz, Caceres, Merida, Plasencia and Zafra (–50.4 %, –71.6 %, –55.2 %, –64.6 % and –51.8 %, respectively), likely due to the limitation of road traffic as the primary source of nitrogen oxides (NOx). These percentages of reduction are similar to data reported in high polluted areas. Similarly, O 3 levels have decreased slightly by –9.9 % in Badajoz, –9.5 % in Merida and –18.2 % in the Monfrague National Park. The reduction in O 3 levels may be due to a decrease in NOx limiting atmospheric conditions and the influence of weather conditions (high cloudiness and rainy days) during the lockdown period. No defined trend was observed for VOCs (BTX), probably due to the very low levels of these contaminants, close to the detection limit both during the lockdown and the reference periods.