Air pollution monitoring using Sentinel-5 (Case study: Big industrial cities of Iran)

Air pollution and its negative effects on human health have become a major issue around the world, especially in developing countries and Iran. Contaminants such as nitrogen dioxide, sulfur dioxide, carbon monoxide, and aerosols, in addition to having significant negative health consequences, cause to damage vegetation and contribute to global climate change. Therefore, the comprehensive monitoring of pollutants and, consequently, appropriate management decisions to address the issue is required. Remote sensing methods, especially Sentinel-5, the European Space Agency's most recent project (in collaboration with the Netherlands), which allows for the capture of images in various spectral bands using a TROPOspheric Monitoring Instrument (TROPOMI)sensor, are recognized as a useful tool for monitoring various types of air pollutants.-

In this analysis, the most significant air contaminants such as nitrogen dioxide, sulfur dioxide, carbon monoxide, and aerosol were monitored using Sentinel-5 satellite images for 20 major industrial cities in Iran in 2019 and 2020. A large number of level-3 images collected from Google Earth Engine were used in this research. Ground-based stations were used to verify the monitoring process.-

The results show that monitoring values obtained using Sentinel-5 satellite images are at least 78 percent correlated with ground-based station values. As a result, it has been demonstrated that Sentinel-5 satellite images can be successfully used in management studies with the aim of reducing air pollution. Based on the results, it can also be inferred that, Tehran and Zanjan are respectively the most and the least polluted city in terms of total carbon monoxide, nitrogen dioxide, sulfur dioxide and dust in 2019. The same is true in 2020. It is also clear that air pollution levels in Karaj and Kermanshah increased significantly in 2020 compared to 2019. Another significant finding is that, in general, air pollution levels in 2020 are lower than in 2019. One significant explanation may be the effect of the Covid-19 pandemic in 2020, which resulted in a decrease in industrial activity and reduced traffic and congestion on the roads.-

In general, the results of this research showed that it is possible to systematically monitor the air pollutants using images captured by TROPOMI sensor on the Sentinel-5 satellite with acceptable accuracy. The results of this study can help researchers and urban managers for appropriate management in metropolitan areas.