Observing air quality in Egypt’s Alexandria port based on the consequences of the COVID-19 lockdown

Abstract The COVID-19 pandemic has significantly affected global society, influencing public health, economies, and the environment. This study examines the environmental impact of the pandemic on Alexandria Port, a key maritime hub in Egypt. By analyzing Automatic Identification System (AIS) data from the port area and multi-temporal satellite imagery from the Sentinel-5 Precursor (Sentinel-5p) satellite, the study investigates the changes in shipping activities and pollution emissions from 2018 to 2022. The aim was to assess the effect of the COVID-19 preventive measures on air quality in the vicinity of Alexandria Port, using satellite data provided by the European Space Agency’s geospatial processing engine. The study focused on several air quality parameters, including carbon monoxide (CO), nitrogen dioxide (NO₂), sulfur dioxide (SO₂), ozone (O₃), and aerosol properties such as Aerosol Optical Depth (AOD) and Absorbing Aerosol Index (AAI). The results revealed varying degrees of reduction in air pollutants during the COVID-19 lockdown, with each pollutant showing a distinct change in levels. Specifically, the AAI and AOD reached their lowest mean values in 2020, recording -1.2 and 214 mol/m 2 , respectively, which represents a significant reduction. Likewise, NO₂ and SO₂ concentrations dropped to their lowest mean values of 0.000048 and 0.000125 mol/m 2 during the lockdown period, reflecting a decrease of approximately 30% compared to pre-lockdown levels in 2018–2019. Notably, CO and O₃ levels showed considerable reductions as well, with CO decreasing to 0.015 mol/m 2 and O₃ reaching 0.125 mol/m 2 , both of which represented decreases of around 10% and 15%, respectively, compared to their 2019 levels. However, following the resumption of full-capacity maritime operations at Alexandria Port, pollution levels returned to pre-lockdown values, indicating that the environmental benefits of the lockdown were short-term. The study concludes that the COVID-19 lockdown had a positive short-term impact on air quality, particularly in reducing harmful pollutants like NO₂, SO₂, and aerosols. However, these improvements were transient, with pollution levels rebounding to pre-lockdown levels once maritime activities resumed. This highlights the importance of continuous monitoring and enforcement of environmental regulations to ensure long-term improvements in air quality. Effective pollution management strategies must be implemented to sustain the environmental gains observed during the pandemic lockdown.