The impact of COVID-19 on air pollution in Iran in the first and second waves with emphasis on the city of Tehran

Air pollution is one of the biggest environmental problems that has gradually spread since the industrial revolution with the consumption of fossil fuels. This situation is more visible in the capitals of industrialized and densely populated countries and towns. In late 2019, with the outbreak of the Coronavirus from China around the world, governments imposed strict restrictions on traffic and transportation to combat the epidemic. With the reduction of consumption of petroleum products in the industry and transportation system, air pollution has decreased in many cities in the world. Materials and methods: In this study, air pollution in the provinces of Iran has been collected and analyzed more than 4500 data. Data on 40 days of quarantine from 1 March to 9 April 2020 were examined. Results: The results of this study show that the concentrations of pollutants CO, NO2, PM10, and PM2.5 decreased by 11, 15, 10, and 6%, respectively, during the lockdown period; but, the SO2 and O3 concentration increased by 15 and 12%. The highest decrease in air pollution is related to Gilan province (-66) and the highest increase in pollution is related to Isfahan province (+37) percent. Calculations show that the Air Quality Index (AQI) has decreased by 6%, but in the second wave of the disease decreased by 75% compared to the lockdown period. Conclusion: The Coronavirus crisis has shown that air pollution can be addressed through the proper implementation of environmental policies