key: cord-1016638-pyqn1qrk
authors: Yang, Mingyu; Chen, Lin; Msigwa, Goodluck; Tang, Kuok Ho Daniel; Yap, Pow-Seng
title: Implications of COVID-19 on global environmental pollution and carbon emissions with strategies for sustainability in the COVID-19 era
date: 2021-11-16
journal: Sci Total Environ
DOI: 10.1016/j.scitotenv.2021.151657
sha: 65e275f59c47d0f55e3a478a3f842e8bb84efeae
doc_id: 1016638
cord_uid: pyqn1qrk

The impacts of COVID-19 on global environmental pollution since its onset in December 2019 require special attention. The rapid spread of COVID-19 globally has led countries to lock down cities, restrict traffic travel and impose strict safety measures, all of which have implications on the environment. This article aims to systematically and comprehensively present and analyze the positive and negative impacts of COVID-19 on global environmental pollution and carbon emissions. It also aims to propose strategies to prolong the beneficial, while minimize the adverse environmental impacts of COVID-19. It systematically and comprehensively reviewed more than 100 peer-reviewed papers and publications related to the impacts of COVID-19 on air, water and soil pollution, carbon emissions as well as the sustainable strategies forward. It revealed that PM2.5, PM10, NO2, and CO levels reduced in most regions globally but SO2 and O3 levels increased or did not show significant changes. Surface water, coastal water and groundwater quality improved globally during COVID-19 lockdown except few reservoirs and coastal areas. Soil contamination worsened mainly due to waste from the use of personal protective equipment particularly masks and the packaging, besides household waste. Carbon emissions reduced due mainly to travel restrictions and less usage of utilities though emissions from certain ships did not change significantly to maintain supply of the essentials. Sustainable strategies post-COVID-19 include the development and adoption of nanomaterial adsorption and microbial remediation technologies, integrated waste management measures, “sterilization wave” technology and energy-efficient technologies. This review provides important insight and novel coverage of the environmental implications of COVID-19 in more than 25 countries across 5 global regions to permit formulation of specific pollution control and sustainability strategies in the COVID-19 and post-COVID-19 eras for better environmental and human health.

The combat against the severe acute respiratory syndrome coronavirus (SARS-CoV-2) has been a top priority for more than 200 countries worldwide since January 2020 (Casado-Aranda et al., 2021) . The outbreak has put an unprecedented burden on healthcare, law enforcement agencies, public administration as well as information and communication sector. The cumulative number of confirmed COVID-19 cases worldwide has exceeded 244 million. COVID-19 has caused nearly 5 million deaths so far (Johns Hopkins University Coronavirus Resource Center, 2021). COVID-19 has resulted in many global impacts such as social, economic and environmental impacts. The economic stability of many countries is affected by lockdowns caused by the pandemic, and the restrictions of economic activities in those countries have resulted in the closure of some businesses and the loss of jobs (Casado-Aranda et al., 2021; Cheval et al., 2020; Saadat et al., 2020) . In terms of J o u r n a l P r e -p r o o f Journal Pre-proof social implications, some severe COVID-19 cases can lead to heart damage, respiratory failure, acute respiratory distress syndrome, and even death (especially in the elderly, who are at high risk of death from the disease) (Rume and Islam, 2020) , leading to fear among the global population. The pandemic, which affected people worldwide, has caused major social disruptions, with the cancellation of major international and domestic flights and the breakdown of transportation systems (Mousazadeh et al., 2021; Saadat et al., 2020) . Access to basic and essential facilities is also affected by restrictions due to the pandemic (Mousazadeh et al., 2021) . Therefore, it is worth analyzing what impacts COVID-19 have on the environment in an in-depth manner. In contrary to the negative socioeconomic impacts, lockdown has also brought some positive environmental improvements to the majority of the countries around the world (Rupani et al., 2020) . Rupani et al. (2020) revealed that most countries in the world have witnessed significant decrease of air pollution, and many countries and regions have reported a continuous reduction of greenhouse gases affecting global warming during the pandemic period. Yunus et al. (2020) have similarly elucidated that pollution of the hydrosphere (including lakes, rivers, oceans, and groundwater reservoirs) has been temporarily mitigated, with pollution levels in the hydrosphere generally lower than during the pre-COVID-19 period. Meanwhile, a substantial decrease in carbon emission was noted during the time of COVID-19 lockdown (Praveena and Aris, 2021; Yunus et al., 2020) . It is worth noting that although the novel coronavirus has brought positive indirect effects on the environment, it has also resulted in negative indirect effects. For example, soil-based contamination has become more intense than before because some urban areas have suspended recycling programs and sustainable waste management has been restricted. COVID-19 lockdown has resulted in an increase in organic and inorganic municipal wastes (Zambrano-Monserrate et al., 2020) . Furthermore, there is growing concern about global warming or climate change as one of the most urgent crises presently (Nguyen et al., 2021) . Although carbon dioxide is not classified as an air pollutant, it is the most important greenhouse gas contributing to global warming.

Carbon emissions from human activities have posed threats to the world by increasing global warming and intensifying climate change. Low rainfall, seasonal changes and temperature rise as a result of climate change could lead to low agriculture production (Yoro and Daramola, 2020) . Additionally, climate change is also associated with rising sea levels, increased frequency and intensity of storms, as well as a host of socioeconomic and health problems. The activities that produce the most carbon are industries, transport, energy generation, buildings, deforestation, and agriculture (Huisingh et al., 2015) . Hofmann et al. (2019) demonstrated that the increase in atmospheric carbon contributes to ocean acidification and that effective removal of CO 2 emissions could well mitigate ocean acidification and its impacts on the marine ecosystems.

The novelty of this literature review is that it is the first systematic discussion of (1) Variations in air pollution in different regions of the world during the COVID-19 pandemic;

(2) Variations in water pollution in different regions of the world during the COVID-19 pandemic;

(3) Variations in soil pollution in different regions of the world during the COVID-19 pandemic;

(4) Va riations in carbon emission in different regions of the world during the COVID-19 pandemic; and (5) Measures to control environmental pollution as well as reduce carbon emissions after the COVID-19 pandemic. Meanwhile, some practical strategies will be proposed to promote future sustainability.

used in this paper were Scopus and Web of Science because of the wide range of papers available in these databases. The papers were searched using relevant keywords, including implications of COVID-19, global environmental pollutions, air pollution, water pollution, soil pollution, carbon emissions, environmental monitoring system, waste management system, and green economy recovery plan. The search included only scholarly articles that were in English and had been peer-reviewed prior to publication.

Initial search of the papers revealed over 1000 articles published since the COVID-19 outbreak in December 2019. Since the initial search included all papers on the global environmental impacts of COVID-19, further selection was based on the WHO's delineation of regions to single out papers that focus on the variations in environmental impacts in different continents such as Asia, America, Africa, Europe, and Oceania, Papers that do not differentiate the regions of impacts were removed.

Subsequently, studies related to the impacts of COVID-19 on environmental pollution and carbon emissions in specific regions of the world were screened according to the purpose and scope of this paper. The screening yielded more than 100 papers. The Endnote software was also utilized in this process to review the abstracts and general contents of the articles for their relevance. Only studies on the effects of COVID-19 on environmental pollution and carbon emissions in specific countries of the world were extracted and further examined. After careful examination based on the WHO's delineation of regions, 118 papers were selected, which covered the effects of 9 COVID-19 on air pollution, water pollution, soil pollution, and carbon emissions, respectively. Finally, based on the review of the impacts of COVID-19 on global environmental pollution and carbon emissions, sustainability strategies in the era of COVID-19 were proposed. 

Data related to population and percentage of urban population (%) were obtained from: Countries in the world by population (Worldometers, 2021) . The acceptance rate and daily mask wear per capita are assumed to be 80% and 2, and the weight of masks (tonne) and mask shells (tonne) have been calculated at 4E-6 and 1E-7, respectively (Naughton, 2020; Nzediegwu and Chang, 2020; Tripathi et al., 2020) .

These data are vital for estimation COVID-19 related daily face mask usage in specific regions.

The estimation of daily face mask usage uses three steps as follows: (1) Total used facemasks (tonnes per day) = population x urban population rate x facemask acceptance rate x average daily use of facemasks per capita x 4E-6 tonne/ per facemask; (2) Total plastic packaging (tonnes per day) = population x urban population rate x facemask acceptance rate x average daily use of facemasks per capita x 1E-7 tonne/per facemask; (3) Total solid waste disposal (tonnes per day) = Total used facemasks + Total plastic packaging.

In view of the quick transmission of COVID-19, many governments around the world have issued lockdowns to avoid the spread of the coronavirus (Hoang et al., 2021a) . The mandatory lockdown imposed by governments to combat this deadly disease is considered the most ambitious isolation measure in the history of J o u r n a l P r e -p r o o f humankind. The lockdown has become a benchmark for cities and countries around the world (Le et al., 2020) . Lockdown restrictions can significantly reduce the spread of the virus. Atalan (2020) identified through research that effective lockdown at the onset of COVID-19 might have prevented an pandemic. Nonetheless, the lockdown measures have also given rise to a wide range of psychological, environmental, and economic effects.

Air pollution is caused by activities such as traffic, industries, refineries, and agricultural activities. COVID-19 caused changes in the levels of air pollution around the world. These changes were due to lockdown and social distancing measures implemented to combat the pandemic, which reduced activities that cause air pollution. This section evaluates the changes in air pollution around the world. 2020) were measured and compared with before the MCO (January 1 to March 17, 2020). The study found a reduction of PM 10 , NO 2 , and SO 2 by 0.4%, 54.2%, and 36%, respectively, during the MCO period compared to before the MCO (Othman and Latif, 2021) . In Iraq, a study was carried out to compare air pollutants concentrations during six different periods of lockdowns . The study found a decrease of PM 2.5 , PM 10 , and NO 2 by 23.7%, 15.15%, and 7.14%, respectively, during the total lockdown period (March 17 to April 21, 2020) as compared to the partial lockdown period (March 1 to 16, 2020). Although many authors reported a decrease in air pollution due to the pandemic, some authors reported ambiguity in air pollution J o u r n a l P r e -p r o o f reduction. reported a decrease in PM 2.5 of 9.23, 6.37, 5.35, and 30.79 μg/m 3 in Beijing, Shanghai, Guangzhou, and Wuhan, respectively. However, these decreases were not enough to avoid severe air pollutions in the regions.

Additionally, the author noted a smaller decrease in PM 2.5 compared to other pollutants, which was due to unfavorable meteorological conditions. Furthermore, Almond et al. (2021) reported an ambiguity in the reduction of air pollutants during COVID-19 lockdown in China. The authors reported that even in previous years, air pollution was already improving in China. Additionally, COVID-19 lockdown happened around the same time as the Lunar New Year period which was observed to have lower air pollutants than other periods of the year in previous years. Lastly, the author argued that, although there was a significant drop in NO 2 due to a decrease in use of transportation, there was an increase in O 3 and the decrease in SO 2 was very slight, hence the overall changes in air pollution did not yield significant health benefits.

In California, US, a respective drop of 38%, 49%, and 31% in NO 2 , CO and PM 2.5 were observed during the lockdown period (March 19-May 7) 2020 compared to the pre-lockdown period (January 26-March 18) 2020 (Liu et al., 2021c) . In Peru, air pollution data were sourced from satellites during quarantine in 2020. The study revealed that the concentrations of CO, O 3, and HCHO decreased by 80%, 5.53%, and 70% respectively in May during quarantine as compared to March before quarantine, J o u r n a l P r e -p r o o f as shown in (Brandao and Foroutan, 2021) . Additionally, the PM 2.5 particulates were studied but there were no significant changes observed during and before COVID-19, which was attributed probably to the wildfires which generated particulates over the period of the study. In Edmonton, Canada, a decrease of NO 2 and CO by 78.6% and 50% was observed during the lockdown period in 2020 compared to the year 2018 (Tian et al., 2021) . There was no significant change in the SO 2 concentrations.

In Cairo, Egypt, there was a decrease in NO 2 and CO by 15% and 5%

respectively during the lockdown in 2020 compared to the baseline period of 2015-2019 (Mostafa et al., 2021) . In Casablanca, Morocco, a decrease in NO 2 , PM 2.5 , and CO concentrations by 12 μg/m 3 , 18 μg/m 3 and 0.04 mg/m 3 was observed respectively during lockdown in 2020 as compared to years 2016-2019 for the same period (Khomsi et al., 2021) . In Port Harcourt, Nigeria, a study on the air quality index revealed a respective decrease of CO, PM 2.5 and PM 10 from a range of 8 -28

ppm, 20 -140 μg/m 3 and 15 -135 μg/m 3 before lockdown to a range of 4 -16 ppm, 10 -110 μg/m 3 and 10 -90 μg/m 3 during lockdown (Adeyemi et al., 2021) . (Sbai et al., 2021) .

In South Island New Zealand, the concentrations of PM 2.5 , PM 10 , and NO 2 reduced by 22.6%, 34.1%, and 50%, respectively, during level 4 lockdown from

March 26-April 27, 2020, compared to the years 2015-2019 before the pandemic J o u r n a l P r e -p r o o f (Talbot et al., 2021) . In Sydney, Australia, the concentrations of NO 2 and PM 2.5 decreased by 7.9% and 10.8% in April 2020 during restrictions compared to April 2019 before the pandemic. The changes, however, were less compared to other countries (Brimblecombe and Lai, 2021) .

It is clear that most of the pollutants and particulate matters such as PM 2.5 , PM 10 , NO 2 , and CO decreased in most cities around the world during the COVID-19

lockdown phases, as shown in Fig. 2 . In contrast, the ozone concentration increased in different cities due to the decrease in nitrogen dioxide that depletes the ozone in the atmosphere. Additionally, SO 2 also increased in different cities because it was produced by fossil fuel combustion in industries and powerplants which continued operations even during the lockdown period. The air pollution and particulates data in the studies reviewed were collected mainly from national air quality monitoring stations and satellites, which were reported to be reliable ( Table 2) . The data obtained were then analyzed by statistical software.

J o u r n a l P r e -p r o o f (Collivignarelli et al., 2020) 14

Africa-Morocco Air quality stations (Khomsi et al., 2021) 15

Africa-Nigeria Integrated modelling of atmospheric composition/ EGVOC-180 (Adeyemi et al., 2021) 16

Africa-Egypt Satellite monitoring (Mostafa et al., 2021) 17

Oceania-New Zealand Stations/ random forest algorithms (Talbot et al., 2021) 18

Oceania-Australia Monitoring stations/ Vassarstat (Brimblecombe and Lai, 2021) J o u r n a l P r e -p r o o f

With COVID-19 spreading globally, the risk of infection from the new coronavirus is forcing governments around the world to take measures to quarantine and maintain social distance. The cessation of recreational commercial activities at beaches and harbors has reduced the risk of coastal water contamination with harmful substances such as plastics. This has led to a temporary improvement in coastal environmental conditions, with beaches in conditions closer to marine protected areas (Ormaza-Gonzaìlez et al., 2021) . Meanwhile, same as coastal water, surface water quality has also improved in a short period of time due to nationwide lockdowns implemented. Surface water improved because continuous domestic sewage, industrial effluent and agricultural wastewater discharges into surface water catchments during lockdown significantly decreased, which reduced the risk of heavy metal pollution as well as other pollution in the surface water Tokatlı and Varol, 2021) . Groundwater contamination also appeared to be getting better during the COVID-19 lockdown (Karunanidhi et al., 2021a) . However, the problem of water contamination also exacerbated in some places during the pandemic and is foreseen to rebound after the pandemic has been effectively controlled.

The quality of surface water has been affected by urban development, industrial Note: ◆ indicates that COVID-19 has a positive impact on the pollution of surface water. ◇

indicates that COVID-19 has a negative effect on the contamination of surface water.

From the summary in Table 3 

Clean coastal water is essential for marine life and the health of beach visitors.

Coastal water contamination is a serious environmental health risk affecting most of the coastal environments of the world. Hence, monitoring and improving coastal water quality has become a necessity . A study on coastal marine litter pollution by Okuku et al. (2021) demonstrated that most of the coastal litter originated from soil and that the source of pollution was mainly made up of plastics.

Coastal ecosystems around the world account for about 10% of the total ocean area.  Anti-viral polymeric textile waste may also have long-term negative effects on the aquatic environment.

(Ardusso et al.,

Note: ◆ indicates that COVID-19 has a positive impact on the pollution of coastal water. ◇

indicates that COVID-19 has a negative effect on the contamination of coastal water. Nevertheless, it is worth noting that the increase in the production of personal protective equipment (PPE) such as masks and gloves in Argentina has also caused a J o u r n a l P r e -p r o o f more serious problem of plastic disposal, which eventually led to a further contamination of coastal waters.

Groundwater is an essential global resource for irrigation as well as domestic and industrial activities, in particular in arid and semi-arid regions (Karunanidhi et al., 2021a (Aravinthasamy et al., 2021) . The research findings on groundwater contamination during the outbreak suggest that the pandemic lockdown did have a positive effect on the alleviation of groundwater contamination.

Overall, the different categories of water bodies around the world (including surface water, coastal water and groundwater) have significantly improved during the COVID-19 lockdown, with the exception of a few reservoirs and coastal water areas

where the lockdown has resulted in mismanagement and improper disposal of PPE waste, which has led to further water pollution. The two comprehensive tables above also illustrate that water pollution problems in all regions of the world have been mitigated by the pandemic lockdown. The variations of water quality of different types of water bodies during the pandemic is presented in Fig. 3 . 

The leading cause of COVID-19 on soil pollution is the increasing accumulation of solid waste. Since the outbreak of the novel coronavirus in December 2019, governments around the world have taken a number of measures to prevent and control the spread of the virus. Because COVID-19 is highly infectious, it can spread rapidly through air and respiratory droplets (Heller et al., 2020; Ren et al., 2020) . As a result, governments around the world have begun to advise people to wear masks properly to reduce person-to-person contact, which can effectively reduce the spread of the virus through air or respiratory droplets (WHO, 2020) . Since the outbreak of the virus, the demand for masks has been increasing. Masks have become necessary J o u r n a l P r e -p r o o f for people going to work, shopping, schools, and other outdoor activities. Used masks, plastic packaging, personal protective equipment, and other disposable plastic protective equipment have led to a steady increase in solid waste and pollution on soil (Patrício Silva et al., 2021b) . As plastics and waste masks affect the natural ecosystem and people's health (Patrício Silva et al., 2021b) . J o u r n a l P r e -p r o o f J o u r n a l P r e -p r o o f

After the outbreak of COVID-19, the continuous increase in the amount of medical waste caused significant difficulties in managing plastic waste and even paralyzed the waste disposal system in many countries. Before the COVID-19 outbreak, medical waste and plastics were disposed of normally in accordance with each region's waste management regulations. These wastes were first sorted according to their characteristics, and sterilized. Then, most of the wastes were transported to designated sites for incineration and landfill, and some of the plastic waste recycled by sterilization technology (Khoo et al., 2021) . However, the rapid spread of COVID-19, the high risk of infection, and the diverse modes of transmission have caused an increasing demand for medical devices in various countries (Tian et al., 2020) , resulting in varying degrees of impacts on the management of medical waste. This is especially true in countries with larger populations, which have more urgent needs for medical devices and at the same time generate more solid waste. Therefore, Table 5 above analyzes the used mask generation, disposal, and the associated environmental impacts of the top eight most populous countries after the COVID-19

outbreak.

According to the analysis results in 

Bangladesh 411.06 tonnes. This is based on the acceptance rate of 80% of the population and the use of 2 masks per day. In fact, each country produces not only masks but also disposable gloves, disposable gowns, and other plastic waste every day.

In addition, some plastic shell waste is generated due to the packaging of masks.

According to the calculations in Table 5 above, China produces about 140.48 tonnes of plastic shells per day due to mask use, India produces the second highest at 77.28 tonnes, and the least is Bangladesh which produces 10.28 tonnes of plastic shell waste.

Therefore, in terms of total mask waste, China has to deal with about 5759.60 tonnes per day, about 14 times more than Bangladesh and 11 times more than Pakistan.

In collecting and analyzing the literature, we found that during the COVID-19

pandemic, the disposal of the proliferating plastic wastes in all of these eight countries, except the United States and Indonesia, were affected to varying degrees. These plastic wastes are typically disposed of by incineration, landfill, or a combination of incineration and landfill, all of which are not well-equipped for resource recovery.

Since viruses may contaminate these wastes, some countries also disinfect the wastes before incineration or landfill, which invariably increases the cost of waste disposal (Khoo et al., 2021) . In addition, these wastes are not well treated in some countries.

For example, in India, due to the overloaded solid waste management, these mask wastes and plastic shells were discarded around the garbage cans to pollute the surrounding environment and soil (Ganguly and Chakraborty, 2021) . In Pakistan, these solid wastes were burned in the open, which released large amounts of toxic J o u r n a l P r e -p r o o f gases and substances to pollute the air and soil (Khalid et al., 2021; Shah et al., 2021) .

In addition, the increase in plastic wastes after the COVID-19 outbreak made it impossible to recycle them in Brazil. As a result, 19,000 m 3 of the landfill had to be added, which seriously polluted the soil and damaged the ecosystem (Urban and Nakada, 2021) . In China, since COVID-19 was first discovered in China and the number of infected people was high, the local government had to add many solid waste disposal centers to incinerate the plastic wastes and these wastes were not recycled effectively, thus causing environmental pollution (Sangkham, 2020; Singh et al., 2020a) . Finally, in Nigeria and Bangladesh, these medical wastes were sent to the vicinity of landfills and dumped randomly without proper disposal, which increased the risk of virus transmission, as well as soil contamination and ecological pollution Oyedotun et al., 2020) . These masks and plastic shells are not biodegradable because the molecular bonding of their plastic structures makes them incapable of decay, and the low melting point of plastics would lead to the release of large amounts of harmful gases when plastic wastes are incinerated (Benson et al., 2021; Potrykus et al., 2021) . Therefore, during the COVID-19 pandemic, solid waste management in different countries was affected to some extent due to the unprecedented growth of plastic wastes, which caused soil pollution and ecological damage.

During COVID-19 lockdown, many human activities stopped as a result of curfew;

J o u r n a l P r e -p r o o f hence this caused a change in the emissions of carbon and other greenhouse gases around the world as reviewed in this section. The world energy report of 2020 by IEA stated that there was a decline of 3.8% of global energy demand which resulted in a 5%

decline of global carbon emissions in the first quarter of 2020 as compared to that of 2019. There were also local changes in carbon emissions as highlighted below.

A study was conducted for the Western Singapore straits on the carbon emissions from marine traffic during COVID-19 lockdown in 2020 which were compared to those in 2019 (Ju and Hargreaves, 2021) . The results showed that carbon emissions of bulk carriers, container ships, tankers, and tugs ships increased by 15.7%, 1.3%, 6.15%, and 1.12%, respectively, in 2020 compared to 2019. In contrast, the carbon emissions of ferry, general cargo, passenger, and RoRo ships decreased by 75.82%, 0.84%, 28.35%, and 0.73% respectively, in 2020 compared to 2019. This is because non-essential travel was not allowed during the COVID-19 lockdown, hence a decrease in emissions due to lower ship trips. Another study was conducted in China to compare carbon emissions from fuel vehicles from 2018 to 2020 during and after lockdown . The results showed that in February 2019, the CO 2 emission (in 10,000 tonnes) was 4045.19. The emission level dropped to 2363.82 in February 2020 but rose to 3409.97 in April 2020. The reason for the drop in February 2020 was the strict lockdown imposed by the Chinese government, which caused fewer vehicles on the road. However, the CO 2 emissions rose again after just 2 months J o u r n a l P r e -p r o o f due to effective pandemic control, leading to some provinces resuming activities.

Another research was done in Xi'an China to compare the carbon emissions before lockdown and during lockdown by directly measuring the CO 2 concentration in the atmosphere . The results showed that CO 2 concentration during total lockdown period (Feb 5 to Feb 21, 2020) were 7.5% lower than before lockdown period (Jan 25 to Feb 4, 2020).

A study was done at the Bournemouth University in UK to compare the carbon footprint on campus during lockdown (April-June 2020) and before lockdown (April-June 2019) (Filimonau et al., 2021) . During lockdown, the carbon emissions dropped from 2140 to 1521 tonnes of CO 2 -eq. Additionally, the largest share of carbon emissions in 2019 was contributed by student and staff commute, followed by utilities. In 2020 during the lockdown, the largest share of carbon emissions was attributed to student and staff working from home activities. This was due to campus closure and online learning, which decreased commute and energy use around campus.

Another research was conducted in France to determine the short-and long-term COVID-19 effects on carbon emissions using the Computable General Equilibrium

Model. The results show that during the 55-day lockdown in 2020, the carbon emissions dropped by 6.6%; however, the drop was short-lived as carbon emission levels rose again after the pandemic (Malliet et al., 2020) . Another study was done at the Algeciras port in Spain on the ships' carbon emissions during lockdown at the J o u r n a l P r e -p r o o f berth, and the results were compared with during their regular operation times. During lockdown, the daily carbon emission from ships was only 6.2 tonnes, while during normal operation, the level was 121.5 tonnes (Durán-Grados et al., 2020) .

Research was conducted in Los Angeles and Washington DC/Baltimore areas in the USA to determine the CO 2 emissions change in 2020 lockdown compared to previous years by using atmospheric observations (Yadav et al., 2021 March and April of 2020 respectively compared to previous years. In Colombia, the emissions of the first half of 2020 during travel restrictions were compared with the those of the same period in 2018. The study found a decrease in 28% of CO 2 emissions during the COVID-19 period, which was mainly due to a decrease in the burning of fuels for transportation (Camargo-Caicedo et al., 2021) .

In Egypt, based on the results of the carbon footprint method, the GHGs emissions during the curfew period from January to August 2020 reduced by 17% compared to the same period in 2019 (Madkour, 2021) . The GHG emissions reduced J o u r n a l P r e -p r o o f due to the reduction of transport such as cars and aviation and reduction of energy use at workplaces due to stay-at-home policies.

In New Zealand, air travel restrictions during COVID-19 lockdown caused a decrease in carbon emissions from airplanes from 250,000 kgCO 2 -eq in August 2019

to almost zero in April 2020 but the emissions rose to 50,000 kgCO 2 -eq in July 2020

due to the loosening of travel restrictions (Becken and Hughey, 2021) .

Based on this section's review, it is evident that carbon emissions were reduced in different cities worldwide (Fig. 4) , primarily due to less travel and less energy use in workplaces during the pandemic. The only rise in carbon emissions observed was due to the operations of essential ships such as bulk carriers and tankers that did not stop during covid-19 to keep the supply chains stable.

J o u r n a l P r e -p r o o f protective equipment such as masks generated due to implementation of safety measures and the increased amount of household waste generated by people during home quarantine and travel restrictions. Therefore, it is necessary to prolong the environmental benefits on air and water from COVID-19 to improve future sustainability. At the same time, since COVID-19 has negative impacts on soil pollution, it is essential to reduce the worsening of soil pollution problems through appropriate measures and strategies. Last but not least, carbon emissions have also decreased during COVID-19 era. This would be beneficial for many countries to achieve the goals of the Paris agreement and to achieve sustainability. Maintaining this improvement is also a subject of consideration for governments as well as municipal residents. The following subsections suggest a number of specific strategies to prolong the benefits of COVID-19 on air, water and carbon emissions as well as to tackle the negative impacts of COVID-19 on soil pollution.

J o u r n a l P r e -p r o o f

The unexpected outbreak of COVID-19 has led to an unprecedented and widespread shutdown of agriculture, industry and commercial activities around the world. It is because of the COVID-19-related restrictions that governments around the world are beginning to realize that air and water pollution can be gradually mitigated.

Strategies that can prolong the benefits of COVID-19 to air and water pollution comprise:

(ⅰ) National governments need to establish laws and regulations to control air and water pollution during COVID-19 and after the end of the pandemic. For example, regional governments can enact environmental tax laws to impose higher taxation on pollutants. At the same time, policymakers can consider increasing tax rates in low-tax areas and strengthening tax incentives to stimulate enterprises to achieve pollutant emissions reduction . Governments likewise can formulate policies that disincentivize motorized modes of transportation particularly in urban areas, while rewarding non-motorized modes (Othman and Latif, 2021; Ravindra et al., 2021) . Zhou et al. (2021) suggest that further improvements to the water pollution issue can be achieved in accordance with the Water Pollution Control Action Plan (i.e., the "10-Point Water Plan").

(ⅱ) Strengthening the environmental monitoring system. The establishment of a National Ambient Air Quality Monitoring Network (NAAQMN) will allow for a better understanding of the relationship between emissions and air pollution patterns, J o u r n a l P r e -p r o o f and enable improved air quality management. An international three-dimensional monitoring strategy has been proposed to characterize the three-dimensional distribution of atmospheric constituents to reduce uncertainty and facilitate diagnostic understanding and prediction of air pollution (Liu et al., 2021a; Liu et al., 2021b) .

(iii) Applying new science and technologies to further reduce air and water pollution.

Research has demonstrated that using new technologies to improve industrial efficiency can significantly reduce reliance on coal-fired power generation and thus reduce air pollution problems (Yue et al., 2021) . Meanwhile, the utilization of nanostructured adsorbents and phytoremediation-related methods can effectively reduce various pollutants in sewage, and the combination of microorganisms and aquatic plants (microbe-integrated phytotechnology) is also a prospective technological method (Hu and Li, 2021; Zamora-Ledezma et al., 2021) .

Soil pollution was further exacerbated by the massive amount of municipal solid waste and medical waste generated during the pandemic as a result of home quarantine. It is urgent to adopt control and management measures for solid waste and medical waste. The various governments should establish a waste management system that is reliable and can ensure an inclusive approach for all stakeholders.

Policymakers ought to impose serious restrictions on the disposal of hazardous waste, the amount of waste that can be released into the environment, the definition and classification of hazardous and non-hazardous substances, and the perfection of laws J o u r n a l P r e -p r o o f related to incineration and other less centralized waste disposal methods (Das et al., 2021a; Torkashvand et al., 2021) . Training the formal workforce and adding integrated measures such as automated or mobile incinerators to develop a highly resilient Soil Pollution Treatment System is also an effective strategy (Ganguly and Chakraborty, 2021) . Meanwhile, in the era of COVID-19, the use of "sterilization wave" technology is helpful in the treatment of medical waste. Autoclave treatment not only helps reduce the risk of exposure to infectious medical waste, but also reduces the weight of the waste and consequently the burden of soil contamination (Das et al., 2021b; Zhao et al., 2021) . While increasing the recycling efficiency of solid waste, it is also necessary to take some scientific and professional measures (e.g.

microbial degradation of waste) to reduce the negative impacts of solid waste and medical waste on the environment (Patrício Silva et al., 2021a).

Available studies show that the pandemic contributed to a substantial decrease in carbon emissions. This is beneficial for the sustainability of development in many countries and the achievement of the Paris Agreement targets. However, preventing a retaliatory increase in carbon emissions after COVID-19 is an additional challenge as well. First of all, the green economy recovery plan is worthy of global attention.

Promoting energy-efficient technologies and strengthening R&D on energy-saving technologies to improve the utilization of energy are important approaches to reduce carbon emissions. There is also a need for more clean and renewable energy in the J o u r n a l P r e -p r o o f current energy system. In fact, there is great potential for the development of sustainable resources and renewable energy infrastructure to prolong the beneficial impacts of COVID-19 on carbon emissions. Governments should establish short-term policies and develop medium-and long-term operational schemes to attain specific renewable energy targets (Hoang et al., 2021b) . In the long term, governments are encouraged to promote trade openness, as adherence to free trade will help achieve global emissions reduction targets. The regulatory adjustments needed to achieve sustainable reductions in carbon emissions may include: imposing minimum energy efficiency standards on residential buildings, implementing zero carbon emission targets for new buildings, limiting access to clean air areas for highly polluting vehicles, banning the sale of new diesel and gasoline vehicles Wang et al., 2021) . Secondly, carbon emissions reduction can also be achieved by adopting an optimal structure of travel. Carbon footprint studies have shown that emissions can be easily reduced by replacing air travel with high-speed railway travel. Since the reduction in ultrafine particle and black carbon concentrations is related to the reduction in traffic flow, the control of traffic flow in and after the COVID-19 era is also an effective approach (El Geneidy et al., 2021; Hudda et al., 2020) .

This article reviews the variations of global environmental pollution and carbon emissions during the COVID-19 pandemic to determine the specific implications of 

Short-Term Air Quality Gains of COVID-19 Pandemic Lockdown of Port Harcourt

A satellite-based investigation into the algae bloom variability in large water supply urban reservoirs during COVID-19 lockdown

Ambiguous Air Pollution Effects of China's COVID-19 Lock-down

COVID-19 lockdown impacts on heavy metals and microbes in shallow groundwater and expected health risks in an industrial city of South India

COVID-19 pandemic repercussions on plastic and antiviral polymeric textile causing pollution on beaches and coasts of South America

Is the lockdown important to prevent the COVID-19 pandemic? Effects on psychology, environment and economy-perspective

Impacts of changes to business travel practices in response to the COVID-19 lockdown in New Zealand

COVID pollution: impact of COVID-19 pandemic on global plastic waste footprint

Significant impacts of COVID-19 lockdown on urban air pollution in Kolkata (India) and amelioration of environmental health

Changes in U.S. air pollution during the COVID-19 pandemic

Impact of COVID-related lockdowns on environmental and climate change scenarios

Air Quality in Southeast Brazil during COVID-19 Lockdown: A Combined Satellite and Ground-Based Data Analysis

Subtle Changes or Dramatic Perceptions of Air Pollution in Sydney during COVID-19

Effect of COVID-19 Anthropause on Water Clarity in the Belize Coastal Lagoon

Emissions Reduction of Greenhouse Gases, Ozone Precursors, Aerosols and Acidifying Gases from Road Transportation during the COVID-19 Lockdown in Colombia

Analysis of the scientific production of the effect of COVID-19 on the environment: A bibliometric study

Cleaning the river Damodar (India): impact of COVID-19 lockdown on water quality and future rejuvenation strategies. Environment, Development and Sustainability

COVID-19 Pandemic Consequences on Coastal Water

Quality Using WST Sentinel-3 Data: Case of Tangier

Observed and Potential Impacts of the COVID-19 Pandemic on the Environment

Lockdown for CoViD-2019 in Milan: What are the effects on air quality? Science of The Total Environment

Surface Water Quality in the Mantaro River Watershed Assessed after the Cessation of Anthropogenic Activities Due to the COVID-19 Pandemic

COVID-19 and municipal solid waste (MSW) management: a review. Environmental Science and Pollution Research

COVID-19 pandemic and healthcare solid waste management strategy -A mini-review

Calculating a Drop in Carbon Emissions in the Strait of Gibraltar (Spain) from Domestic Shipping Traffic Caused by the COVID-19 Crisis

The carbon footprint of a knowledge organization and emission scenarios for a post-COVID-19 world

The carbon footprint of a UK University during the COVID-19 lockdown

Integrated approach in municipal solid waste management in COVID-19 pandemic: Perspectives of a developing country like India in a global scenario

Impact of the COVID-19 outbreak on air pollution levels in East Asia

Impact of COVID-19 Lockdown on Air Quality in Moscow

Investigation of COVID-19 Lockdown Effects on Water Quality in Natural Bodies of Water in the Great Lakes Region. World Environmental and Water Resources Congress

On the investigation of COVID-19 lockdown influence on air pollution concentration: regional investigation over eighteen provinces in Iraq

COVID-19 faecal-oral transmission: Are we asking the right questions? Science of The Total Environment

UK COVID-19 lockdown: 100 days of air pollution reduction?

An analysis and review on the global NO 2 emission during lockdowns in COVID-19 period

Impacts of COVID-19 pandemic on the global energy system and the shift progress to renewable energy: Opportunities, challenges, and policy implications

Strong time dependence of ocean acidification mitigation by atmospheric carbon dioxide removal

Treatment Technology of Microbial Landscape Aquatic Plants for Water Pollution

Reductions in traffic-related black carbon and ultrafine particle number concentrations in an urban neighborhood during the COVID-19 pandemic

Recent advances in carbon emissions reduction: policies, technologies, monitoring, assessment and modeling

Perception and Attitudes Toward PPE-Related Waste Disposal Amid COVID-19 in Bangladesh: An Exploratory Study. Frontiers in Public Health

Extended Ecological Restoration of Bacterial Communities in the Godavari River During the COVID-19 Lockdown Period: a Spatiotemporal Meta-analysis

Changes in air pollution levels after COVID-19 outbreak in Korea. Science of The Total Environment

The impact of shipping CO 2 emissions from marine J o u r n a l P r e -p r o o f traffic in Western Singapore Straits during COVID-19

Groundwater Pollution and Human Health Risks in an Industrialized Region of Southern India: Impacts of the COVID-19 Lockdown and the Monsoon Seasonal Cycles

Effects of COVID-19 pandemic lockdown on microbial and metals contaminations in a part of Thirumanimuthar River, South India: A comparative health hazard perspective

Current practices of waste management in teaching hospitals and presence of incinerators in densely populated areas

Assessment of the impact of COVID-19 lockdown on the heavy metal pollution in the River Gomti, Lucknow city

COVID-19 national lockdown in morocco: Impacts on air quality and public health. One Health

Plastic waste associated with the COVID-19 pandemic: Crisis or opportunity

A remarkable review of the effect of lockdowns during COVID-19 pandemic on global PM emissions

Do environmental taxes reduce air pollution? Evidence from fossil-fuel power plants in China

Carbon emission post-coronavirus: Continual decline or rebound?

Stereoscopic Monitoring: A Promising Strategy to Advance Diagnostic and Prediction of Air Pollution

Does national air quality monitoring reduce local air pollution? The case of PM2.5 for China

Spatiotemporal impacts of COVID-19 on air pollution in California, USA. Science of The Total Environment

Measuring the Level of Environmental Performance on Coastal Environment during the COVID-19 Pandemic: A Case Study from Cyprus

Did the Coronavirus Disease 2019 Lockdown Phase Influence Coastal Water Quality Parameters off Major Indian Cities and River Basins? Frontiers in Marine Science

Suggested guidelines for emergency treatment of medical waste during COVID-19: Chinese experience

Monitoring the impacts of COVID-19 pandemic on climate change and the environment on Egypt using Sentinel-5P Images, and the Carbon footprint methodology

Assessing Short-Term and Long-Term Economic and Environmental Effects of the COVID-19 Crisis in France

Investigating connections between COVID-19 pandemic, air pollution and community interventions for Pakistan employing geoinformation technologies

Decline in Phytoplankton Biomass along Indian Coastal Waters due to COVID-19 Lockdown

Spatio-Temporal Analysis of Surface Water Quality in Mokopane Area

The impact of COVID 19 on air pollution levels and other environmental indicators -A case study of Egypt

Will the COVID-19 pandemic change waste generation and composition?: The need for more real-time waste management data and systems thinking. Resources, Conservation and Recycling

Record decline in global CO 2 emissions prompted by COVID-19 pandemic and its implications on future climate change policies

Improper solid waste management increases potential for COVID-19 spread in developing countries. Resources, Conservation and Recycling

The impacts of COVID-19 pandemic on marine litter pollution along the Kenyan Coast: A synthesis after 100 days following the first reported case in Kenya

COVID-19 Impacts on Beaches and Coastal Water Pollution at Selected Sites in Ecuador, and Management Proposals Post-pandemic. Frontiers in Marine Science

Air pollution impacts from COVID-19 pandemic control strategies in Malaysia

Municipal waste management in the era of COVID-19: Perceptions, practices, and potentials for research in developing countries

Imprints of COVID-19 lockdown on the surface water quality of Bagmati river basin

An urgent call to think globally and act locally on landfill disposable plastics under and after covid-19 pandemic: Pollution prevention and technological (Bio) remediation solutions

Increased plastic pollution due to COVID-19 pandemic: Challenges and recommendations

Polypropylene structure alterations after 5 years of natural degradation in a waste landfill

The impacts of COVID-19 on the environmental sustainability: a perspective from the Southeast Asian region. Environmental Science and Pollution Research

Lessons from the COVID-19 air pollution decrease in Spain: Now what? Science of The Total Environment

Impact of COVID-19 lockdown on ambient air quality in megacities of India and implication for air pollution control strategies. Environmental Science and Pollution Research

New method to reduce COVID-19 transmission-the need for medical air disinfection is now

Air Pollution Monitoring in Peru Using Satellite Data During the Quarantine Due to COVID-19. IEEE Aerospace and Electronic Systems Magazine

Environmental effects of COVID-19 pandemic and potential strategies of sustainability

Coronavirus pandemic (COVID-19) and its natural environmental impacts

Environmental perspective of COVID-19. Science of The Total Environment

Face mask and medical waste disposal during the novel COVID-19 pandemic in Asia. Case Studies in Chemical and Environmental Engineering

Air quality change during the COVID-19 pandemic lockdown over the Auvergne-Rhone-Alpes region

Understanding temporary reduction in atmospheric pollution and its impacts on coastal aquatic system during COVID-19 lockdown: a case study of

Energy trilemma based prioritization of waste-to-energy technologies: implications for post-COVID-19 green economic recovery in Pakistan

Challenges, opportunities, and innovations for effective solid waste management during and post COVID-19 pandemic. Resources, Conservation and Recycling

Novel insights into impacts of the COVID-19 pandemic on aquatic environment of Beijing-Hangzhou Grand Canal in southern Jiangsu region

Amplified ozone pollution in cities during the COVID-19 lockdown

COVID-19 waste management: effective and successful measures in Wuhan, China. Resources, Conservation,Recycling

Diurnal and temporal changes in air pollution during COVID-19 strict lockdown over different regions of India

An investigation of the impacts of a successful COVID-19 response and meteorology on air quality in New Zealand

Characteristics of COVID-19 infection in Beijing

Assessing the impact of COVID-19 pandemic on urban transportation and air quality in Canada

Impact of the COVID-19 lockdown period on surface water quality in the Meriç-Ergene River Basin

Municipal solid waste management during COVID-19 pandemic: a comparison between the current activities and guidelines

Challenges, opportunities and progress in solid waste management during COVID-19 pandemic. Case Studies in Chemical

COVID-19 pandemic: Solid waste and environmental impacts in Brazil. Science of The Total Environment

Assessment of Water Quality Along the Southeast Coast of India During COVID-19 Lockdown. Frontiers in Marine Science

Severe air pollution events not avoided by reduced anthropogenic activities during COVID-19 outbreak. Resources, Conservation and Recycling

Preventing carbon emission retaliatory rebound post-COVID-19 requires expanding free trade and improving energy efficiency. Science of The Total Environment

Preventing a rebound in carbon intensity post-COVID-19 -lessons learned from the change in carbon intensity before and after the 2008 financial crisis. Sustainable Production and Consumption

Advice on the use of masks in the context of COVID-19: interim guidance

The impact of COVID-19 lockdown on atmospheric CO 2 in

Lockdown effects on total suspended solids concentrations in the Lower Min River (China) during COVID-19 using time-series remote sensing images

The Impact of COVID-19 on CO 2 Emissions in the Los Angeles and Washington DC/Baltimore Metropolitan Areas

CO 2 emission sources, greenhouse gases, and the global warming effect. Advances in Carbon Capture

The potential of industrial electricity savings to reduce air pollution from coal-fired power generation in China

COVID-19 and surface water quality: Improved lake water quality during the lockdown. Science of The Total Environment

Indirect effects of COVID-19 on the environment

Heavy metal water pollution: A fresh look about hazards, novel and conventional remediation methods

Impact of COVID-19 pandemic on energy consumption and carbon dioxide emissions in China's transportation sector. Case Studies in Thermal Engineering

Comparative life cycle assessment of emergency disposal scenarios for medical waste during the COVID-19 pandemic in China

Does the "10-Point Water Plan" reduce the intensity of industrial water pollution? Quasi-experimental evidence from China

Writing -Original Draft Lin Chen: Writing -Original Draft Goodluck Msigwa: Writing -Original Draft

Tang: Conceptualization; Writing -Review & Editing Pow-Seng Yap: Conceptualization

J o u r n a l P r e -p r o o f