Assessing the impacts of COVID-19 pandemic on the environment: A correlation or causation?

The outbreak of the COVID-19 pandemic has severely impacted human lives, human activities, and the world economy. In response to curb its spread, pandemic risk reduction measures such as mass lockdowns, extensive travel bans, and mass quarantine were imposed globally. While the imposition of these measures has negatively impacted the world economy, its impacts on the environment could be described as a gain, as the ecosystem appears to be given a rebirth. During the mass lockdown (February to April 2020), air pollution worldwide has dropped signifi cantly precisely, with a decline in the emission and concentration of pollutants. The emission of CO2 globally declined by 8.8% during the fi rst half of 2020. Additionally, both surface and underground water quality have been improved due to reduced industrial activities. Also, there has been an increase in carbon sink due to the decline in global bush fi res. In a nutshell, the study recommends that as the world economy recovers from the impact of COVID-19, world leaders and policymakers should focus on measures that improve the environment and the ecosystem, such as the adoption of the green economy, production and use of fuel cells cars instead of gasoline cars and treating industrial effl uents to WHO recommended levels before discharging them into water bodies. Mini Review Assessing the impacts of COVID-19 pandemic on the environment: A correlation or causation? Sikpaam Issaka Alhassan1, Justice Delali Akoto1, Michael Ackah2, Stephen Mintah3, Feiping Zhao1,4 and Haiying

to kidney failure in severe cases [4]. Various risk reduction measures such as cluster lockdown, social distancing, extensive travel bans, and mass quarantine were imposed in different countries. The situation has impacted both regional and global socio-economic growth [5]. Subsequently, the effects of these measures range from a surge in commodity prices, disruption of supply chains, less demand for imported goods and services, a decline in international tourism and business travel to increasing economic anxiety [6].
Despite all the imbalances mentioned above that the outbreak of COVID-19 poses on the society and the economy, such as increased mortality and economic shutdown, we must see the silver lining out of the dark cloud.  [7]. This has positive implications on our health, agriculture, and general wellbeing as it has signifi cant impacts on the atmosphere, hydrosphere, and the lithosphere.
Again, it is projected that pollutants from major industries that affect aquatic ecosystems, such as industrial wastewater or effl uents, crude oil, heavy metals, and plastics, would have stopped entirely hence a corresponding reduction in water pollution. For instance, the Grand Canal in Italy, where the COVID-19 crippled the whole nation, turned clear, giving life and providing a habitable environment to many aquatic species [8]. Similarly, a sacred but severely polluted river in India, after several lockdown days, turned cleaner at several places [9]. Moreover, Yunus, et al. [10] investigated surface water quality in India (Vembanad Lake, the longest freshwater lake showed that the SPM quantified for April 2020 was the lowest for 11 out of 20 zones of the lake. Also, a recent study found out that the mean values of Dissolved Oxygen (DO) and Biological Oxygen Demand (BOD) of the Ganga river were found to be (>6 mg/l) and (<2 mg/l) respectively, with a Total Coliform of 5000 per 100 ml and pH range of 6.5 to 8.5 [11]. This indicates an improvement in the surface water quality considering the PH, DO and the BOD, the study added. Similarly, the water quality at the famous religious site, Haridwar Ghats in India, has also improved during the lockdown with mean concentrations of DO, BOD found to be 8 mg/l and 2.1 mg/l respectively.
The upstream's pH was 7.9 which was same as that of the downstream with an absolute DO (7.90) and BOD (2.1 mg/l) [12].
The imposition of extreme measures to control the virus has potentially led to a decrease of aerosols and atmospheric pollutants due to the reduction in the disruption of anthropogenic-based emissions. Aerosols either directly or indirectly contribute to both regional and global climate changes [13]. For instance, increased Aerosol Optical Depth The magnitude of such a decline in CO 2 emissions is the highest ever recorded in the world's history, even higher than similar economic downturns such as world war two (-790 Mt) and the Spanish fl u. In Figure 1 above, it could be seen that daily CO 2 emissions for 2020 have declined sharply owing to the COVID-19 spread as compared to 2019. However, by early May, the emission of CO 2 started increasing ( Figure 1A what remains clear is that the outbreak of COVID-19 with its imposed lockdowns has led to a signifi cant reduction in the concentration and emissions of pollutants and other dangerous chemicals on the environment. This benefi t provides us with clean air, clean water, and clean soil better off than hitherto existed. This comes from the cut in the pollution emitted from burning fossil fuels in industries, transports, agriculture, and residential areas. Therefore, we could postulate that there is a causation between COVID-19 lockdown and the reduction in the emission of pollutants on the environment. Lastly, Li, et al. [16] undertook an air quality study during the COVID-19 lockdown period in China around the Yangtze river delta region (YRD). YRD is one of the main economic hubs in Eastern China with multiple industrial activities. The study showed that SO 2 , NO x , PM 2.5 , and VOCs emissions reduced by approximately 16-26%, 29-47%, 27-46%, and 37-57% during level I (January 24 -February 25) and level II (February 26 -March 31) respectively. This further confi rms satellite imageries published by the National Aeronautics and Space Administration (NASA) that the lockdown measures have led to a massive reduction in NO 2 hence improving the global air quality. In Figure 2 below, we can see that atmospheric pollution in China captured by satellite has reduced signifi cantly during the lockdown (February 10-25) as compared to before the lockdown (January 1-20), a clear indication of the impact of lockdown on pollutant's emission. Similarly, a reduction in NO 2 levels was also observed in major cities across the world. According to the European Environmental Agency, the average NO 2 concentrations in Rome around March 2020 were 26 -35 percent lower than the same period in 2019. Other European cities like Madrid and London have recorded 51 percent and 60 percent reduction in NO 2 respectively compared to the same period in 2019 [17].

Conclusion
This paper presents a brief overview of the impacts of the COVID-19 pandemic on the environment to postulate the possible relationship between COVID-19 preventive measures such as mass lockdown and the environment. While we admit that the outbreak of COVID-19 has had enormous impacts on  our health and the world economy, which may take decades to recover fully. It is also essential to note that the lockdown has impacted positively on our environment in innumerable ways such as improved air quality due to a decline in the emission of pollutants such as CO 2 , CO, NO 2 , PM 2.5 , improved underground and surface water quality, and increase in carbon sink due to decline bush fi res. While pollution of water bodies from domestic activities remained the same during the lockdown, industrial pollution and pollution from tourism signifi cantly reduced, leading to improved air and water quality. The overall effects of this on our society are that it leads to a decline in climate change with improved air, water, and preservation of aquatic life. Lastly, the emergence of the COVID-19 pandemic has underscored the fact that when we destroy the environment or the ecosystem, we destroy the system that supports human life. As such, world leaders should formulate a policy that would ensure that every country observes at least a partial-tototal lockdown on world environment day (5 th June ) every year to minimize the effect of human activities on the ecosystem.