The Impact of COVID-19 Lockdowns on Air Quality—A Global Review

Abdullah Addas,Ahmad Maghrabi

doi:10.3390/su131810212

Abstract

The outbreak of the COVID-19 pandemic has emerged as a serious public health threat and has had a tremendous impact on all spheres of the environment. The air quality across the world improved because of COVID-19 lockdowns. Since the outbreak of COVID-19, large numbers of studies have been carried out on the impact of lockdowns on air quality around the world, but no studies have been carried out on the systematic review on the impact of lockdowns on air quality. This study aims to systematically assess the bibliographic review on the impact of lockdowns on air quality around the globe. A total of 237 studies were identified after rigorous review, and 144 studies met the criteria for the review. The literature was surveyed from Scopus, Google Scholar, PubMed, Web of Science, and the Google search engine. The results reveal that (i) most of the studies were carried out on Asia (about 65%), followed by Europe (18%), North America (6%), South America (5%), and Africa (3%); (ii) in the case of countries, the highest number of studies was performed on India (29%), followed by China (23%), the U.S. (5%), the UK (4%), and Italy; (iii) more than 60% of the studies included NO2 for study, followed by PM2.5 (about 50%), PM10, SO2, and CO; (iv) most of the studies were published by Science of the Total Environment (29%), followed by Aerosol and Air Quality Research (23%), Air Quality, Atmosphere & Health (9%), and Environmental Pollution (5%); (v) the studies reveal that there were significant improvements in air quality during lockdowns in comparison with previous time periods. Thus, this diversified study conducted on the impact of lockdowns on air quality will surely assist in identifying any gaps, as it outlines the insights of the current scientific research.

Highlights

The novel coronavirus (SARS-CoV-2) originated from Wuhan in December 2019, and later spread to many countries across the world [1]
India (29%), followed by China (23%), the U.S (5%), the UK (4%), and Italy; (iii) more than 60% of the studies included NO2 for study, followed by PM2.5, PM10, SO2, and CO; (iv) most of the studies were published by Science of the Total Environment (29%), followed by Aerosol and Air Quality
From the overall studies surveyed, it was observed that the greatest number of studies on the impact of the COVID-19 pandemic on air quality was performed on Asian countries

Summary

Introduction

The novel coronavirus (SARS-CoV-2) originated from Wuhan in December 2019, and later spread to many countries across the world [1]. In many parts of the world, severely affected countries imposed lockdowns to prevent the transmission of COVID-19 by restricting transportation, economic, and industrial activities. In many previous research studies, it is welldocumented that many countries of the world are facing serious public health problems due to extreme air pollution [2,3,4,5]. More than 60% of the populations living in urban areas are severely exposed to the serious problem of air pollution [1]. Both high-income (56%) and low-income (98%) countries of the world fail to meet the guidelines proposed by WHO [1]

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