Marzieh Akbari - Social Determinant of Health (SDH) Research Center and Department of Environment Health and Kashan University of Medical Sciences, Kashan, Iran.
Reza Ali Fallahzadeh - Genetic and Environmental Adventures Research Center, School of Abarkouh Paramedicine, Shahid Sadoughi University of Medical Sciences, Yazd, Iran.
Rouhullah Dehghani - Social Determinant of Health (SDH) Research Center and Department of Environment Health and Kashan University of Medical Sciences, Kashan, Iran.

Introduction: The COVID-۱۹ epidemic has polluted millions of people and has caused millions of deaths worldwide. Therefore, this study aims to review the effects of COVID-۱۹ on global air pollution. Materials and Methods: In this narrative review, articles related to the objectives of the study were selected in reliable scientific databases such as Web of Science, Ovid, Google Scholar, PubMed, and Scopus. A total of ۲۹۴ browsing sources and ultimately ۹۰ sources were selected. Results: In the COVID-۱۹ pandemic, NO۲ dropped from ۵۳ to ۱۱% in most countries, and PM۲.۵ and PM۱۰ from ۹۱ to ۶% in some countries. CO dropped from ۹۲ to ۵% and SO۲ had a decreasing trend from ۷۷ to ۷% in most countries, except for the largest cities in Britain, Poland, Taiwan, and Iran. Unlike other pollutants, O۳ in most countries increased from ۰.۳ to ۶۳%, but O۳ decreased in some countries. Conclusion: In the lockdown period, the reduction of most air pollutants except O۳ was observed in many countries. But after restarting, polluting activities have incresed again. Therefore, the rules implemented during lockdown time can be introduced as an appropriate option in emergencies to reduce air pollution.

Air Pollution, COVID-۱۹, Pneumonia, Epidemic.