ABSTRACT

One of the economic challenges facing developing countries is the cost of tackling air pollution and improving its quality. In this study, we propose a comparative analysis of the tropospheric nitrogen dioxide (NO₂) column spatial configuration over Tehran between pandemic conditions and normal conditions, based on the European Space Agency (ESA) Copernicus Sentinel-5P products. Comparison of the time series of nitrogen dioxide obtained from Sentinel-5P data showed that NO₂ levels in 2020 were between 4 × 10⁻⁵ and 6 × 10⁻⁵ mol/m², while in 2019 the amount of nitrogen dioxide many times exceeded 6 × 10⁻⁵ mol/m². Based on the data obtained from Sentinel-5P, the northern, north-eastern, and central regions of Tehran were registered as the most polluted areas in terms of nitrogen dioxide. The results showed that due to the change of normal conditions in 2019 to quarantine conditions due to coronavirus pandemic (COVID-19) in 2020, the density of tropospheric NO₂ columns decreased, which is due to the temporary restriction of industrial activities, traffic, and population density. The correlation analysis between ground dataand data from Sentinel-5P provided encouraging values with a Pearson’s correlation coefficient of 0.58 (2019) and 0.61 (2020), and the amount of nitrogen dioxide in 2020 decreased by 6% compared to 2019.