Comparison of the Effect of Social Restrictions on Covid-19 pandemic on Nitrogen Dioxide Pollutant in Five Wildlife Refuges and their Large Neighboring Cities in Iran

The aim of this study was to determine the effect of Covid-19 pandemic and the resulting social restrictions on changes in nitrogen dioxide levels at five Iranian wildlife refuges, including Heydari, Miankaleh, Qomishlu, Bakhtegan and Shadegan, and five large cities close to them including Mashhad, Sari, Isfahan, Shiraz and Khuzestan, respectively. A comparison between these data was made with similar periodic to the year before the pandemic. The data required for atmospheric monitoring were gained from the NASA database between February 19 and June 1, 2019, as well as from February 19 to June 1, 2020, and were analyzed in Python, MATLAB, and MINITAB softwares. The results of statistical analysis showed that the average levels of pollution in 2019 were significantly different between large cities and between wildlife refuges, while in 2020 there was no significant difference. Also, results showed that covid-19 had a significant effect on reducing the amount of nitrogen dioxide in Sari and Miankaleh wildlife refuge. The amount of this pollutant for Shadegan and Ahvaz city in 2020 was less than 2019, but it was not much different for Shadegan. The social restrictions have had a significant reduction on the levels of nitrogen dioxide in Mashhad, so that the amount of this pollutant has decreased by an average of 44% during the three-month period, but due to lack of information in The Heydari Shelter cannot be judged for the entire three-month period. Nitrogen dioxide in the Bakhtegan has not been changed significantly in the three month of 2019 and 2020. Although in Shiraz until April 13, along with April 15, the amount of nitrogen dioxide due to covid-19 decreased significantly, but from April 13 onwards, the amount of this pollutant has been higher than in the previous year. Further studies will be need to identify the restrictive effects of Covid-19 pandemic on the status of other atmospheric pollutants in Iranian wildlife refuges.