key: cord-290458-5fwbh9t9
authors: Lal, Preet; Kumar, Amit; Kumar, Shubham; Kumari, Sheetal; Saikia, Purabi; Dayanandan, Arun; Adhikari, Dibyendu; Khan, M. L.
title: The dark cloud with a silver lining: Assessing the impact of the SARS COVID-19 pandemic on the global environment
date: 2020-05-08
journal: Sci Total Environ
DOI: 10.1016/j.scitotenv.2020.139297
sha: 
doc_id: 290458
cord_uid: 5fwbh9t9

Abstract The Severe Acute Respiratory Syndrome-Coronavirus Disease 2019 (COVID-19) pandemic caused by a novel coronavirus known as SARS-CoV-2 has caused tremendous suffering and huge economic losses. We hypothesized that extreme measures of partial-to-total shutdown might have influenced the quality of the global environment because of decreased emissions of atmospheric pollutants. We tested this hypothesis using satellite imagery, climatic datasets (temperature, and absolute humidity), and COVID-19 cases available in the public domain. While the majority of the cases were recorded from Western countries, where mortality rates were strongly positively correlated with age, the number of cases in tropical regions was relatively lower than European and North American regions, possibly attributed to faster human-to-human transmission. There was a substantial reduction in the level of nitrogen dioxide (NO2: 0.00002 mol m−2), a low reduction in CO (<0.03 mol m−2), and a low-to-moderate reduction in Aerosol Optical Depth (AOD: ~0.1–0.2) in the major hotspots of COVID-19 outbreak during February–March 2020, which may be attributed to the mass lockdowns. Our study projects an increasing coverage of high COVID-19 hazard at absolute humidity levels ranging from 4 to 9 g m−3 across a large part of the globe during April–July 2020 due to a high prospective meteorological suitability for COVID-19 spread. Our findings suggest that there is ample scope for restoring the global environment from the ill-effects of anthropogenic activities through temporary shutdown measures.

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

In 2020 a novel coronavirus known as SARS-CoV-2 struck the world through widespread human transmission (Bukhari and Jameel, 2020), creating fears of a new plague similar to the Spanish Flu in 1918 , Mexican Smallpox in 1967 , AIDS in the early 1980s, SARS in 2002 /03, Bird Flu in 2005 , Swine Flu in 2009 /10, and Ebola in 2014 (Harari et al., 2007 . First discovered by the Chinese Center for Disease Control and Prevention , the first case of COVID-19 was reported in the region of Wuhan in the Central Hubei Province of China on 31 st December 2019 TWC India, 2020) . Rising global death tolls combined with the high infectivity of the virus, mild clinical symptoms, an uncertain incubation period, lack of pre-existing human immunity, and the possibility of asymptomatic healthy carriers (Bouey, 2020) led to the WHO declaring COVID-19 a "Public Health Emergency of International Concern (PHEIC)" on 30 th January 2020 (World Health Organization, 2020a) . COVID-19 is transmitted via droplets and fomites (contact with contaminated surfaces) (Bouey, 2020), with children less affected than adults and the elderly.

A coronavirus patient can transmit the disease to three people on average without intervention (compared with one for the common influenza, two for Ebola, and 18 for measles) . Symptoms of COVID-19 range from mild clinical symptoms similar to the common cold or flu (Guo et al., 2020; Peeriet al., 2020; Shi et al., 2020; Wang et al., 2020) , with major symptoms appearing 2-14 days from infection and including trouble breathing, persistent pain or pressure in the chest, mental confusion or inability to arouse, and bluish lips or face (CDC, 2020) . Those with persistence symptoms often require specialized respiratory management at intensive care units (Chan et al., 2020; Rodriguez-Morales et al., J o u r n a l P r e -p r o o f To-date there is no known specific and effective pharmacological treatment for COVID-19 (Cortegiani et al., 2020) . Despite China's preventative measures to control the spread of COVID-19, several other countries are still struggling to contain the virus (Dong et al., 2020) .

Various pandemic risk reduction measures such as social distancing, cluster lockdowns, mass quarantines, extensive travel bans, and disruptions to transportation systems have had a direct impact on local and global socio-political relations and economic growth (Long and Feng, 2020) .

Such extreme measures to control the virus have potentially resulted in decreases of aerosols and atmospheric pollutants due to the disruption of anthropogenic-based emissions (https://www.theguardian.com/world/2020/mar/20/coronavirus-the-week-the-world-shutdown). Aerosols have direct and indirect contributions on climate change at regional and global scales (Huang et al., 2014; Menon et al., 2002; Qian and Giorgi, 1999) as increased levels of aerosol optical depth (AOD) affects atmospheric stability and precipitation as aerosols disturb the scattering and absorption of solar radiation (Jiang et al., 2016) , the hydrological cycle (Prasad et al., 2004) and vegetation cover and its growth (Lal et al., 2019; Sarkar and Kafatos, 2004) . In addition to climatic effects, aerosols increase respiratory problems in humans and decrease visibility in urban areas (Prasad et al., 2005) . A study on the 2002/03 Severe Acute Respiratory Syndrome (SARS) showed a positive relationship between long term exposure to air pollution (PM 10 , NO 2 , CO, O 3 , and SO 2 ) in China and a higher risk of dying (84%) in regions of moderate and high air pollution index (Cui et al.,

The COVID-19 pandemic outbreak had brought major economic disruption in the world (Khan et al., 2020; WTO, 2020) , with disruptions in global supply chains, business and consumer confidence, the decline in commodity prices, international tourism and business travel, and less demand for imported goods and services (Boone et al., 2020) . The long-term economic impacts include changes in health care expenditure as well as downstream impacts of COVID-19 on mortality and morbidity (Abiad et al., 2020) , with a rapid increase in economic anxiety in the population at-large (Fetzer et al., 2020) .

Human coronaviruses have shown strong winter seasonality between December and April, becoming undetectable in the summer months in temperate regions of the world (Gaunt et al., 2010) . Average temperature (5-11°C), relative humidity (RH: 47-79%) and latitude profiles exhibited similarity in the timing of COVID-19 outbreak during January 2020 in Wuhan, China, and February 2020 in other affected regions (Sajadi et al., 2020) . Similarly, 90% of COVID-19 cases have been reported in countries with a temperature range of 3° to 17°C and between an absolute humidity (AH) of 4 to 9 g m -3 (Bukhari and Jameel, 2020). Laboratory conditions conducive to the survival of the members of the coronavirus family are low temperatures (4°C), and moderate to high RH (20-80%) (Casanova et al., 2010) . However, the SARS-CoV-2 may survive for several days on plastics and metals at moderate temperatures (between 21-23°C) and a RH of 40% (van Doremalen et al., 2020) . This suggests there may be a direct relationship between temperature, humidity, environmental pollutants, and the spread of SARS-CoV-2. Therefore, the objectives of the present study are to (i) assess the status of COVID-19 cases across the globe, (ii) study the meteorological correlates of COVID-19 occurrences, and (ii) assess the impact of COVID-19 pandemic on the quality of J o u r n a l P r e -p r o o f We used satellite data, COVID-19 reported case data, and meteorological data (Table 1) to assess the impacts of COVID-19 on the global environment. The country-wise cumulative cases of COVID-19 affected-population and death tolls were acquired from WHO (https://www.who.int) and analyzed on a weekly basis until 10 April 2020 in a GIS environment. Temperature and relative humidity hourly datasets of 0.25° were taken from the Copernicus Climate Data Store (CDS), and European Center for Medium-Range Weather Forecast (ECMWF) (https://cds.climate.copernicus.eu) used to calculate Absolute Humidity.

Data on the weekly concentration of carbon monoxide (CO), NO 2 , and AOD for the period of 01 January to 21 April 2020 were acquired and analyzed. The same datasets were acquired for the period of 01 January to 21 April 2019 to compare the variability of said parameters.

Standardized anomalies (SA) of AOD and near-surface air temperature (2m above the surface) for January to March was estimated using equation 1.

.…. Eq 1 Climate Data Operator (CDO) tool was used to estimate standard deviations and climatological mean. Projected near-surface air temperature, and relative humidity (RH) datasets acquired from CIMIP-5 model at RCP 8.5 scenario until November 2020 and were used to estimate the possible impacts of COVID-19 on different countries under future meteorological conditions. Absolute Humidity was calculated using Clausius Clapeyron J o u r n a l P r e -p r o o f and Jameel, 2020). Therefore, global COVID-19 hazard assessment was estimated based on AH on future projected data for the period of April to November 2020. The AH-based hazard map was classified into 4 different classes considering their possible habitat suitability viz., high hazard (AH: 4 to 9 g m -3 ), moderate hazard (AH: 2 to 4 g m -3 and 9 to 12 g m -3 ), low hazard (AH: <2 and 12 to 15 g m -3 ) and very low hazard (AH: >15 g m -3 ). 

The cases related to COVID-19 affected population and death tolls were mapped and analysed ( Figure 1 ). A total of 1240239 persons with confirmed cases and 81661 deaths occurred due to COVID-19 around the world till 10 th April 2020 (World Health Organization, 2020b). The majority of COVID-19 infected cases, as well as death, were reported in the European region (52.6% of total infected persons and 71.4% of total death tolls) followed by the region of Americas (32.4% infections and 18.4% deaths), Western Pacific region (7.7% infections and 4.3% deaths), Eastern Mediterranean region (5.8% infected persons and 5.0% deaths), South-East Asian region (0.9% infections and 0.6% deaths) and African region (0.6% infections and 0.4% deaths) ( Figure 1 ). On the other hand, the percentage of deaths with reference to the total number of confirmed cases was highest in the European region (8.3%), followed by the Eastern Mediterranean region (5.2%), South-East Asian region (4.4%), and African region (4.3%) with the lowest deaths as compared to confirmed cases reported from the region of Americas (3.5%) and Western Pacific region (3.4%) ( Table 2) .

The global country-wise assessment indicated the majority of affected populations were from the United States of America (34.34% of the global cases), followed by Spain (12.29%), Italy J o u r n a l P r e -p r o o f (11.58%), Germany (9.15%), France (6.88%), China (6.72%), Iran (5.34%) and UK (5.25%).

While COVID-19 initially came to attention in the Hubei province of China and subsequently spread to many other regions of the world through global travel (Huang et al., 2020) due to its highly transmissible nature (Bogoch et al., 2020), a consistent pattern of COVID-19 cases was observed from east to west along the 30 o to 50 o N latitude including South Korea, Japan, Iran, and Northern Italy. Notably, COVID-19 failed to significantly spread to countries immediately south of China as the number of patients and reported deaths in Southeast Asia was much lower compared to temperate regions (Dong et al., 2020) . High temperatures (> 40°C) and extremely low temperatures (< 4°C) restrict the spread of the members of the coronavirus family (Casanova et al., 2010) and is expected to diminish COVID-19 considerably in affected areas above 30°N in the coming months (Sajadi et al., 2020) .

The continent level assessment showed that Europe (799696) was severely affected, with the country of Spain (152446) being the most affected country followed by Italy (143626) (3512) were moderately affected, though the number of cases was increasing rapidly. A very low number of cases were reported from J o u r n a l P r e -p r o o f hands could be another reason for widespread of COVID-19. However, the transportation mechanism in western countries, which enables less person to person contact due to usage of personal transport, in contrast to public transport in tropical countries, could be a major source of spread of COVID-19. Health Organization, 2020b), and this pattern proved to be true in other heavily infected countries in Europe and North America. In the United States, 80% of deaths were individuals over 65 years of age (CDC, 2020). Meanwhile, Italy the home to the oldest population in Europe and the second-oldest population in the world, was the most prone to the virus, with 12.8% of the 70-79 age category and 20.2% of those over 80 years of age more likely to die upon infection by COVID-19 (Dutta, 2020; Horowitz, 2020) . Despite this higher death rate, individuals living in Italy have a significantly longer life expectancy than those individuals living in China (Godin, 2020) . This figure is difficult to determine as age-related comorbidities such as cardiovascular disease, diabetes, and hypertension have also been shown to be highly correlated with COVID-19 deaths. The death of COVID-19 patients J o u r n a l P r e -p r o o f without pre-existing medical conditions was very low (only 0.9%), while the likelihood of dying for patients with pre-existing medical conditions like cardiovascular disease (10.5%), diabetes (7.3%) and chronic respiratory disease (6.3%) was very high ( 

Global temperature and absolute humidity were mapped using ERA-5 reanalysis data during the COVID-19 outbreak period (January to March 2020) on a weekly basis to deduce Spatiotemporal variations. An increase in temperature was observed in tropical regions (30°S to 30°N latitude) as compared to temperate regions due to seasonality variations (figure 3). 

Nearly half of the world is under partial or complete lockdown due to the COVID-19

outbreak, leading to the shutdown of industries and motor vehicles and an associated reduction in the concentration of atmospheric pollutants. In the present study, the direct and indirect impact of the COVID-19 outbreak on environmental pollution has been studied using spatio-temporal satellite-based products related to NO 2 , CO, and AOD. Major changes were observed in South Asia and South-East Asian countries including major parts of Indian regions like the IGP, where NO 2 concentration was drastically reduced during the 12 th to 16 th week as compared to previous weeks due to the shutdown of various industries and a travel ban issued on 24 th March 2020. In Western Africa, major changes were observed from 7 th and 8 th week and had been continuously decreasing, whereas major changes in Europe were observed 12 th week onwards. Besides, the variation in global NO 2 concentration is influenced by global wind circulations (Arya, 1999; Grundstrom et al., 2015; Santurtún et al., 2017) . A sharp reduction in NO 2 concentration occurred across the globe, J o u r n a l P r e -p r o o f primarily in the Southern Hemisphere and tropical regions during January to March 2020. As compared to 2019, other highly populated regions of the world (Europe, North America, and IGP) had also observed low (<0.00003 mol m -2 ) to moderate (<0.00005 mol m -2 ) reductions in NO 2 during 2020. These trends may be attributed to regional variations in the timing of the COVID-19 outbreak, as well as the implementation of preventive measures. The incomplete burning of carbon-based fuels leads to the generation of CO which is spread by wind circulation patterns throughout the lower atmosphere (Novelli et al., 1998) . The weekly monitoring of global CO column number density based on daily observation of showing an increase with reference to the previous weeks, which may be attributed by the coverage of desert or proximity to the sea.

The standard anomaly of AOD with reference to the long term monthly mean (2000) (2001) (2002) (2003) (2004) (2005) (2006) (2007) (2008) (2009) (2010) (2011) (2012) (2013) (2014) (2015) (2016) (2017) (2018) (2019) was also evaluated. The study exhibited an increase in area under negative anomaly ( 

The future projections of absolute humidity based on the CIMIP-5 model at RCP 8.5 scenario until November 2020 were used to deduce the possible contribution of meteorological conditions to COVID-19 spread following January-March 2020 variations in AH and Bukhari and Jameel, (2020) concepts of virus transmission at the different threshold of AH. AH plays a significant role in the transmission of SARS- CoV-2 (Carleton and Meng, 2020; Ficetola and Rubolini, 2020; Luo et al., 2020; Oliveiros et al., 2020) . A peak rate of spread of COVID-19 in temperate regions of the Northern Hemisphere having a mean temperature of ~5°C, and AH of 4 to 9 g m -3 during the outbreak period was observed, while it was lower both in warmer/wetter and colder/drier regions (Ficetola and Rubolini, 2020). Nevertheless, J o u r n a l P r e -p r o o f changes in weather alone (i.e., increases or decreases of temperature and humidity) will not necessarily lead to declines in case counts without the implementation of extensive public health interventions (Luo et al., 2020) . Therefore, a prospective global COVID-19 hazard based on AH from April to November 2020 was mapped and analysed (figure 8). The study projected an increasing coverage of high COVID-19 hazard in a large part of the globe during April to July 2020 due to high prospective meteorological suitability (AH: 4 to 9 g m -3 ). The study illustrated a severe and high probability of COVID outbreak in major parts of the Northern Hemisphere as compared to the Southern Hemisphere during May-July 2020 barring primarily tropical regions. Thereafter, a reduction in COVID-19 hazard may be evident in the tropical and subtropical regions during August-September 2020 due to variations in regional meteorological conditions. Later, in October-November 2020, COVID-19 hazard will be resurgent in the tropical and subtropical regions (primarily in the Northern Hemisphere) and reduced in temperate and sub-temperate regions of the globe. In the Asian continent, virus transmission has a low possibility except in China as the majority of countries will have moderate AH (2 to 4 g m -3 and >10 g m -3 ) until September 2020 ( Figure   8 ). The study indicated severe COVID-19 pandemic hazard in the coming months due to meteorological suitability apart from local transmissions. Thus, there are uncertainties associated with our model predictions. Hence, we advise the end users to practise caution while using the predictions.

Based on the above discussion, we conclude that the intensity of transmission of COVID-19

is not uniform in spite of its global spread. Mortality is positively correlated with age-group as well as severe pre-existing medical conditions. There has been a substantial reduction in the emission of atmospheric pollutants viz., NO 2 and AOD because of forced shutdowns reflecting high fossil fuel consumption based human lifestyles in the developed countries. In general, meteorological factors may not be directly related to the number of outbreaks.

However, countries with temperatures between 4°C±2°C to ~19°C±2°C and AH: 4 to 9 g m -3

are at a higher risk of COVID-19 outbreak despite preventive measures. Therefore, in the upcoming months, i.e., May-July 2020, the Northern Hemisphere may be more susceptible to outbreaks compared to tropical regions. However, tropical regions may be prone to outbreaks during the onset of winter in October, and November 2020 and appropriate actions and policy interventions should be implemented at local as well as international levels to contain COVID-19 outbreaks and minimize the consequent damages. International consensus is required for such extreme measures to take place and to ensure the long-term survival of Table 1 : Details of data used J o u r n a l P r e -p r o o f 

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Week 15: 09 Apr to 15 Apr and week

J o u r n a l P r e -p r o o f (Platnick et al., 2014)