"Relationship between Covid-19 and changes in air pollutants using satellite imagery (Case study: Tehran, Isfahan and Mashhad metropolises)"

With the observation of the first confirmed case of Covid-19 in Qom on 20 February 2020, restrictions were imposed by the government and executive agencies to prevent the spread of the Covid-19 virus in all cities of Iran. These restrictions seem to reduce the production and release of air pollutants from human resources. Therefore, this study was conducted to investigate the changes in the time series of sulfur dioxide, nitrogen dioxide, carbon monoxide, and ozone pollutants before and after the outbreak of the Covid-19 virus in three metropolises of Tehran, Isfahan, and Mashhad using Sentinel-5 satellite data. For this purpose, using the Google Earth Engine system, the concentrations of these pollutants are averaged monthly in the two periods of 20 February  2019 to 20 February 2020 for the period before the outbreak of Covid-19 and the period of 20 February 2020 to 20 February  2021 for the period of outbreak of Covid-19 Was considered. Then, to evaluate the significance of the change in the concentration of these contaminants before and after the outbreak of the Covid-19 virus, a t-test (dependent t) was used at a significance level of p-value <0.05. The results of the T-test showed that for sulfur dioxide, nitrogen dioxide, and carbon monoxide pollutants in all three cities there was no significant change in the mean data concentration; But ozone for all three cities had a decreasing trend and a significance level of p-value <0.05. The results of this study showed that the application of restrictions has not been effective in reducing the release of primary pollutants from human resources.