Air Quality and Environmental Effects Due to COVID-19 in Tehran, Iran: Lessons for Sustainability

The 2019 coronavirus disease (COVID-19) global pandemic spread can be considered a disastrous crisis that, in a given geographical area, significantly affects the increase in mortality rate with direct and indirect impacts on different scales and social, economic, political, and ecological factors. The effects of this crisis can be more intense in urban areas with high population density. Due to the more significant presence of vulnerable groups, the risk of death increases significantly. This research describes the environmental impacts of the COVID-19 pandemic in the city of Tehran, the 37th most populated city in the world. The concentration of six air pollutants (carbon monoxide (CO), ozone (O3), nitrogen dioxide (NO2), particulate matter with a diameter of 10 microns (PM10), sulfur dioxide (SO2), particulate matter with a diameter of fewer than 2.5 microns (PM2.5) and the Air Quality Index (AQI) were measured in 22 urban regions of Tehran before (20 March) and from (21 March to 10 February) the lockdown, in air pollution evaluation stations. In order to conduct this research, first, the values of the air pollutant indices of the 22 districts of Tehran in the two previous periods (before 20 March) and during quarantine (21 March to 10 February) were obtained from the air pollution measurement stations of the 22 districts of Tehran, together with the results. After the operationalization and quantification of the indicators according to the research objectives, they were entered into the ArcGIS environment, and the spatial analysis of each pollutant was performed, before and during the quarantine. Finally, it was found that the AQI was reduced from 74.95 to 54.15.