ABSTRACT
Lockdown restrictions due to the COVID-19 pandemic led to air, road and marine traffic limitations as well as to limitations of economic activities causing thus considerable reductions of air pollutant emissions and air quality levels. This paper aims at studying the impact of these restrictions, due to pandemic, on air pollutant emissions and on atmospheric pollutant concentrations in the Greater Area of Athens, Greece. Air pollutant emission levels and emission reductions due to COVID-19 containment measures were calculated and related to air pollutant concentrations from six air quality monitoring stations. Findings showed significant road, marine and air traffic emission reductions, ranging from 20 to 90%. In the analysis conducted, the relation between air pollutant levels and the corresponding emissions was identified showing that the most important contributor to high air pollutant levels is road traffic. The conclusions drawn on air quality levels may provide policy makers with useful insights in order to plan and apply more efficient measures to reduce air pollution and comply with air quality standards and European Directives. © 2022 Gheorghe Asachi Technical University of Iasi, Romania. All rights reserved.
ABSTRACT
Wuhan Tianhe International Airport (WUH) was suspended to contain the spread of COVID-19, while Shanghai Hongqiao International Airport (SHA) saw a tremendous flight reduction. Closure of a major international airport is extremely rare and thus represents a unique opportunity to straightforwardly observe the impact of airport emissions on local air quality. In this study, a series of statistical tools were applied to analyze the variations in air pollutant levels in the vicinity of WUH and SHA. The results of bivariate polar plots show that airport SHA and WUH are a major source of nitrogen oxides. NOx, NO2 and NO diminished by 55.8%, 44.1%, 76.9%, and 40.4%, 33.3% and 59.4% during the COVID-19 lockdown compared to those in the same period of 2018 and 2019, under a reduction in aircraft activities by 58.6% and 61.4%. The concentration of NO2, SO2 and PM2.5 decreased by 77.3%, 8.2%, 29.5%, right after the closure of airport WUH on 23 January 2020. The average concentrations of NO, NO2 and NOx scatter plots at downwind of SHA after the lockdown were 78.0%, 47.9%, 57.4% and 62.3%, 34.8%, 41.8% lower than those during the same period in 2018 and 2019. However, a significant increase in O3 levels by 50.0% and 25.9% at WUH and SHA was observed, respectively. These results evidently show decreased nitrogen oxides concentrations in the airport vicinity due to reduced aircraft activities, while amplified O3 pollution due to a lower titration by NO under strong reduction in NOx emissions. © 2022