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

2.1. Surface and groundwater

Egypt is suffering for a long time from a deterioration of its ground and surface water. This is mainly due to discharge of heavily polluted industrial and domestic wastewaters into its waterways without sufficient treatment (Mostafa and Peters, 2016; Abdel-Satar et al., 2017). The Nile River represents the main freshwater source which provides the country with almost all drinking and irrigation water needs (Mostafa, 2014). The Nile River also provides Egypt with about 65% of its industrial water demands (Abdel-Satar et al., 2017). The quality of the Nile River and its two main branches (Rosetta and Damietta), as well as canals and drains networks located in the Nile Delta are expected to significantly improve during the SARS-CoV-2 pandemic since most of the industries in Egypt are not working with their full capacities, which lead to a decrease in wastewater effluent. For example, the production of ready-made clothes has decreased by about 8.9% in February 2020 comparing to January 2020 due to the SARS-CoV-2 pandemic (CAPMAS, 2020a). The quality of the Nile River is also expected to improve due to the suspension of tourist ships from operation which represents the main source of oil spill in the river (Shara and Moustafa, 2009). All the lakes in Egypt are suffering from poor water quality due to receiving partially or untreated industrial wastewater (Abd El-Hamid et al., 2020). The water quality in these lakes are also expected to improve due to the temporary closure of some industries.

The reduction in industrial activities in Egypt is also expected to some extent to improve groundwater quality since the main aquifer in Egypt (Nile aquifer) is recharged from the Nile river and its branches, as well as canals and drains networks located in the Nile Delta. The pollution in the Mediterranean Sea is also expected to decrease since its connected to both Rosetta and the Damietta branches. The water quality at the Suez Canal is also expected to improve during the SARS-CoV-2 pandemic due to the reduction in the number of ships. A report published by International Food Policy Research Institute (IFPRI) expects a 15% reduction in Suez Canal revenues during the pandemic (Breisinger et al., 2020).

2.2. Beaches

The coastlines of the Egypt are over 3500 km in length that extend along the Red Sea and the Eastern Mediterranean (Masria et al., 2014). Beaches are located in some areas along the coastlines and represent important natural capital assets for these areas. Consequently, they must be protected against overexploitation. They provide services, such as recreation, tourism, sand, and land (Lucrezi et al., 2016; Zambrano-Monserrate et al., 2020). Some beaches in Egypt are suffering from careless behavior that lead to beaches pollution, such as North coast, Ain Sokhna, Alexandria, and Baltim. These beaches are the biggest winners from the containment actions that have been applied in Egypt since the occurrence of SARS-CoV-2 pandemic. They are closed to all forms of public access and uses (Egypt Today, 2020a), and thus they are now look cleaner and with clear waters. Similar observation was reported in many beaches worldwide, such as Barcelona (Spain), Acapulco (Mexico), and Salinas (Ecuador) (Zambrano-Monserrate et al., 2020).

2.3. Environmental noise

Environmental noise is one of the top environmental risks to public health and it is defined as an unwanted or harmful sound generated by commercial or industrial activities, as well as human activities, such as transportation (railway, road traffic, and aircraft), and melodies at high volume (WHO, 2020e; Zambrano-Monserrate et al., 2020). High exposure to environmental noise may lead to release of stress hormones and may cause some diseases, such as arteriosclerosis, hypertension, a stroke, or myocardial infarction (Muzet, 2007). The containment actions applied in Egypt since the SARS-CoV-2 pandemic, especially the curfew and the quarantine, have encouraged people to stay at home, and thus decreasing commercial, industrial, and transportation activities. Such analysis has been confirmed by officially governmental announcements which reported that the reduction in these activities have significantly decreased the level of environmental noise in Egypt by about 75% (Masrawy, 2020; Ahramonline, 2020d), as is the case in most cities around the world.

2.4. Municipal and medical solid wastes

The food consumption in Egypt has increased since the outbreak of COVID-19 as a result of the curfew and “Stay at home” campaign. According to the Community Mobility Report published by Google, mobility trends for places of residence increased by about 20% compared to the baseline (Google, 2020). Staying at home encourages people to overeat which lead to an increase in organic solid waste generated per capita. Egypt has also witnessed a significant increase (940%) in the online shopping due to COVID-19 transmission fears (Nile Fm, 2020), which in turn led to an increase in both organic and inorganic solid wastes. Since the outbreak of COVID-19, safe disposal of municipal solid waste has become a big challenge, especially that the prevailing disposal practice in Egypt is through dropping the wastes in opened unregulated site without precautions to protect the environment. This wastes are now considered hazardous because they may include waste from infected residents, as well as an infected personal protective equipment such as gloves and masks. There is also a big concern worldwide regarding the risk of SARS-CoV-2 spreading in recycling facilities. For example, USA has suspended the recycling programs in some cities to prevent the spread of the virus (Zambrano-Monserrate et al., 2020). In Egypt, recycling facilities are operating normally even during the COVID-19 lockdown. However, they are operating with less than half of their workforce after allowing the workers who have chronic diseases or compromised immune systems to stop working and stay at home. This action negatively affects the efficiency of the recycling process, as well as the quality of the final products (composts and refused derived fuel (RDF)).

Hospitals in Egypt produces an average of 70.5 tons/day of medical waste (SWEEP-Net, 2014), less than 50% of these amount are safely and efficiently discarded through incineration (El Dirini, 2017). The remaining amount is either illegally traded for recycling or mixed with municipal solid waste (SWEEP-Net, 2014). The International Solid Waste Association (ISWA) has announced an increase in medical waste contaminated with Coronavirus by 30%–50% (Al Mal, 2020). During the SARS-CoV-2 outbreak, and as confirmed by the Egyptian government, the quantity of medical waste generated from hospitals in Egypt increased significantly reaching 300 tons/day (Al-Masry Al-Youm, 2020a; Egypt Independent, 2020a). Consequently, this is another serious challenge facing officials in Egypt. Since the SARS-CoV-2 outbreak, the Egyptian Ministry of Environment has checked about 1537 medical facilities to ensure the efficiency of the medical waste management system (Egypt Today, 2020b; Daily News Egypt, 2020a).

One of the indirect positive effects of COVID-19 is the removal of solid waste accumulated in streets during the curfew period, where about 3.3 million tons of municipal solid waste has been removed since the beginning of COVID-19 outbreak in March (Daily News Egypt, 2020b; Youm7, 2020a). Another positive effect is the cleanup of the Red Sea bed in Dahab City, where divers in Dahab have taken advantage of halting tourism to remove about 7 tons of wastes and impurities which gives another life to the coral reefs (Al-Masry Al-Youm, 2020b; Egypt Independent, 2020b).

2.5. Water and wastewater

The concern regarding the transmission of COVID-19 in water and wastewater has increased after detecting COVID-19 (as well as other coronaviruses) in the anal swabs and stool samples of some patients (La Rosa et al., 2020). Many researchers have proved the presence of COVID-19 in municipal wastewater after analyzing samples collected from some cities worldwide, such as Massachusetts (Wu et al., 2020) and Italy (La Rosa et al., 2020). La Rosa et al. (2020) have concluded that COVID-19 has low stability in the environment and is characterized by fast inactivation in water compared to other nonenveloped human and animal enteric pathogenic viruses. The authors have also concluded that SARS-CoV-2 is very sensitive to disinfectants/oxidants, like chlorine. Till now, there is no any published research or document that support the theory of COVID-19 survival in drinking water or wastewater (Zambrano-Monserrate et al., 2020; WHO, 2020f). In Egypt, the chlorine dosages used in water and wastewater treatment plant are adequate for virus inactivation and there is no need to enhance the disinfection process through increasing the injected dosage of chlorine (Youm7, 2020b). However, a more restricted risk management strategy is currently implemented by collecting and analyzing water samples regularly to ensure that the water quality meets the standard (Youm7, 2020b). Some other countries have decided to increase the chlorine dosage in the wastewater treatment plants, like China, to prevent the spread of COVID-19 through the wastewater (Zambrano-Monserrate et al., 2020). It is also worth noting that the excess of chlorine in tap water may cause an adverse health effects in people (Mohsen et al., 2019; Zambrano-Monserrate et al., 2020).

4.1. Nitrogen dioxide measurement

Satellite instruments are able to precisely detect air pollutants such as NO₂, ozone, sulfur dioxide (SO₂), carbon monoxide (CO) and methane (CH₄) (Somvanshi et al., 2019). These tools calculate backscattered radiation from the sun in a broad spectral range from ultraviolet (UV) to infrared wavelengths. Advanced retrieval algorithms are applied to transform the measured radiation to pollutant concentrations, such as a tropospheric column density of NO₂. The National Aeronautics and Space Administration (NASA) has launched Aura satellite on July 15, 2004 which is equipped with ozone monitoring instrument (OMI) to monitor the changes in air quality for many regions worldwide (NASA, 2020a). It is used in this study to monitor the changes in NO₂ emissions over Egypt before and during the COVID-19 pandemic (NASA, 2020b).

4.2. Ground-level ozone and carbon monoxide measurement

The Geospatial Interactive Online Visualization and Analysis Infrastructure (Giovanni) has been utilized to get the O₃ and CO concentration data over Egypt. Giovanni web-based tool was developed by the NASA Goddard Earth Sciences (GES) Data and Information Services Center (DISC). The tool provides the researchers with numerous satellite data with about 1600 variables including concentrations of the key air pollutants and other climatological parameters.

4.3. Absorbing aerosol index

European Space Agency (ESA) has launched Sentinel-5 Precursor satellite on October 13, 2017 which is equipped with TROPOspheric Monitoring Instrument (TROPOMI) to measure the level of NO₂, SO₂, CH₄, CO, and ozone (O₃) in the atmosphere (TROPOMI, 2020; Omrani et al., 2020). It can also calculate the AAI value based on wavelength changes in Rayleigh scattering in the ultraviolet spectrum range. TROPOMI is 13 times more accurate than the OMI developed by NASA, where it can daily provide a full map of the global pollutant concentrations, with a resolution of 7 km × 3.5 km (Theys et al., 2019). It is used in this study to get the AAI data over Egypt for 2019 and 2020. For data before 2019, no data on TROPOMI was available; hence, OMI has been utilized.

5.1. Changes in nitrogen dioxide emissions

The data for NO₂ emissions was retrieved from OMI for three months (February, March, and April) for the period from 2015 to 2020. The measured data for the targeted three months in year 2020 representing the pandemic time (Fig. 2 a) was compared to the data for the same months from the previous years (from 2015 to 2019) (Fig. 2b) to logically identify whether the implemented containment measures during COVID-19 outbreak has caused a change in NO₂ emission or not. In Fig. 2, the darker the color, the higher NO₂ concentration/emission. It is obvious that the orange color in Fig. 2a is darker than the orange color in Fig. 2b, indicating a reduction in NO₂ emission in 2020 during the pandemic time comparing to previous 5 years. Fig. 2c also shows that the NO₂ emission has decreased in year 2020 by about 3 × 10¹⁵, 0.8 × 10¹⁵, and 1.5 × 10¹⁵ molecules/cm² for February, March, and April, respectively, comparing to the same month from the previous 5 years. This is mainly attributed to reductions in traffic and industrial activities during the pandemic. This is also matching with the figures generated from the Google community mobility reports which have been developed based on the anonymized data-sets from users (Google, 2020). Therefore, the implemented containment measures during COVID-19 outbreak have improved the air quality in Egypt.

Cairo governorate is the capital of Egypt and has a population of 9.94 million, while Alexandria governorate is the second-largest city in Egypt after Cairo with a population of 5.37 million (CAPMAS, 2020b). Fig. 3 shows a comparison between the NO₂ concentration measured in 2020 by OMI over Cairo and Alexandria with the average concentration for the same period in 2015–2019. The results indicated that the 2020 NO₂ emissions in Cairo and Alexandria is lower than the average level during the same period in 2015–2019. A percentage difference was calculated inside a 1° x 1° box over the city center. At March 15, 2020, where the containment actions were taken to reduce the spread of coronavirus disease, the concentration of NO₂ over Cairo and Alexandria has dropped by about 15% and 33%, respectively, compared with the baseline period. From April 1 to May 1, 2020, the NO₂ emission over Cairo and Alexandria dropped on average by only 13% and 9%, respectively, because most of the factories resumed their operation to provide the essential products needed during the holy month of Ramadan. These findings are also supported by an area chart in supplementary Figure 1 that shows the tropospheric NO₂ emission in the first 120 days of years 2019 and 2020 over Cairo and Alexandria governorates (CESBIO multitemp, 2020). The values are generally in line with the percentage reduction of the gasoline and diesel consumption referred to above. In addition, the values seem logic due to the fact that in normal conditions, the vehicles in Greater Cairo are responsible for 50% of the NO₂ emissions (Abou-Ali and Thomas, 2011; Heger et al., 2019). Fig. 3 also shows that the impact of COVID-19 pandemic on the level of tropospheric on air is not limited to Cairo and Alexandria, but can also be seen over the Nile Delta. Reduction of NO₂ levels during the COVID-19 pandemic has also been observed in several countries/cities including China (Wang and Su, 2020), India (Gautam, 2020a; Sharma et al., 2020), USA (Muhammad et al., 2020), Rio de Janeiro (Dantas et al., 2020), São Paulo (Nakada and Urban, 2020), Milan (Collivignarelli et al., 2020), Barcelona (Tobías et al., 2020), Nice, Rome, Valencia and Turin (Sicard et al., 2020). It is clear that the implemented containment measures during COVID-19 pandemic have reduced the NO₂ emission and thus improved air quality, however, this improvement is not sustainable and deterioration on air quality is expected to occur after the lockdown as it was before the pandemic, as the case in China (Abnett, 2020). Therefore, stricter laws must be enacted to protect the environment in Egypt.

5.2. Changes in ground-level ozone

Fig. 4a presents the difference in concentrations between 2019 and 2020 (2019 subtracted from 2020) during March and April. As shown, the O₃ concentrations in 2020 is less than 2019 in all locations including Cairo and Alexandria; however, it is to be noted that the absolute concentrations are in the range of 300 DU, so the difference is nearly negligible (around 1%). So, it can be said from such results that the monthly O₃ concentrations in March and April are nearly constant and not affected by COVID-19 and its associated partial lockdown. Such results can seem strange especially that the NO₂ which is the precursor of O₃ has decreased over Cairo and Alexandria by 13% and 9%, respectively in April and decreased by higher values in March. However, such inconsistent relation between the NO₂ and O₃ concentrations has been previously observed in a lot of previous research work” (Qin et al., 2004; Lin et al., 2005; Jiménez et al., 2005; Blanchard et al., 2008; Schipa et al., 2009; Castell et al., 2010; Wolff et al., 2013; Adame et al., 2014; Shen et al., 2014; Diéguez et al., 2014; Xie et al., 2016; Silva et al., 2018; Zou et al., 2019; Ezimand and Kakroodi, 2019; Tang et al., 2020; Soares et al., 2020; Liao et al., 2020; Mozaffar et al., 2020; Fang et al., 2020; Barcelo, 2020). In addition, several researchers have recently reported that O₃ levels increased in some cities during COVID-19 lockdown in complete contrast to the NO₂ concentrations (Sicard et al., 2020; Siciliano et al., 2020; Tobías et al., 2020). Such results can be attributed to the complex reaction mechanism governing the generation of ground-level O₃ which depends on various parameters including the VOC/NO_x ratio. In traffic-congested urban cities, where the NO_x levels from the automobiles are high, the VOC/NO_x ratio is low. In such conditions, and in case of any significant reduction in NO_x, the complex photochemical reaction mechanism favors the formation of O₃. On the other hand, in rural areas and where the VOC/NO_x ratio is relatively high, the O₃ is directly proportional to NO_x (Finlayson-Pitts and Pitts, 2000). This is even clearer in Fig. 4b which presents the difference in concentrations between February 2020 (directly before COVID-19 partial lockdown) and March–April 2020 (February subtracted from March–April). As can be noticed, the traffic-congested urban cities like Cairo and Alexandria witnessed an increase in O₃ concentrations during the partial lockdown with about 3%. Hence, and despite having an overall positive influence on primary pollutant levels, it is important to highlight that COVID-19 also has some negative air pollution consequences. On the other hand, it can be observed from Fig. 4b that most of the rural areas had reductions in O₃ concentrations during the partial lockdown with values that can reach about 5% in some locations. In order to assess whether the air pollution levels are more influenced by the aforementioned hypothesis compared to the variation in the meteorological conditions, the O₃ concentrations during March and April 2020 has also been compared to the same months but over a longer baseline period (2015–2019). As shown in Fig. 5 , nearly the same conclusions were observed where the traffic-congested urban cities like Cairo and Alexandria witnessed an increase in O₃ concentrations during the partial lockdown with about 2%, while most of the rural areas had reductions in O₃ concentrations with values that can reach about 2%. Deeper interpretation of O₃ behavior in Egypt during the COVID-19 partial lockdown needs further investigation by analyzing several other factors like reactivity of the VOC mixture (Atkinson, 2000), reduced particulate matter concentration and its impact on increased solar irradiance (Heuss et al., 2003), in addition to the exact prevailing meteorological conditions (Dantas et al., 2019). It worth noting that the measured hourly-average O₃ concentrations comply with the local ambient air quality regulations (180 μg/Nm³). While the O₃ concentrations were not measured on 8-h averaging period; however, it is safe to say that the O₃ also comply with the WHO ambient air quality limits since the measured hourly-average O₃ levels are less than the WHO 8-h limits (100 μg/Nm³). This matches with the literature where it has been reported that the O₃ levels in Egypt significantly increase during summer months compared to other seasons (Steiner, 2014) to the extent that the local ambient air quality regulations can be exceeded during summer (Khoder, 2009).

5.3. Changes in absorbing aerosol index

As shown in Fig. 6 , the 2020 AAI in Egypt was about 30% lower than the AAI level during the same period in 2019, which confirms the positive effect of COVID-19 on the air quality in Egypt. These results agree with the results obtained from OMI, where the AAI was lower at March 15, 2020 compared to April and May 2020. It has been reported in the literature that about 30% of the PM₁₀ and PM_2.5 emissions are generated from the transport sector (especially from old private cars and taxis) at normal conditions in Egypt (World Bank Group, 2013; El-Dorghamy et al., 2015; Heger et al., 2019). A previous statistical study done in Egypt (Heger et al., 2019) has shown that there is a linear correlation between car density and PM₁₀ pollution load, where it was deduced that reducing the number of vehicles by 1% lead to a PM₁₀ load reduction of 0.27%. Another recent study on Cairo during normal conditions (Abbass et al., 2020) has shown that the PM_2.5/PM₁₀ ratio is less than 0.5 which was attributed to the tyre and brake wear (due to traffic congestion), desert environment, having many areas undergoing construction activities and the presence of many unmaintained roads. The containment measures undertook by the Egyptian government has led to less traffic flow and relatively less construction activities. The less traffic flow generally causes less PM emissions from vehicles’ engines especially from the old taxis and public transportation buses, less PM emissions from tyre and brake wear, in addition to less entrained PM emissions from the unmaintained roads. In order to assess whether the air pollution levels are more influenced by the partial lockdown compared to the variation in the meteorological conditions, the AAI values in 2020 has also been compared to a longer baseline period (2015–2019). As shown in Fig. 7 , the same conclusions were observed where the AAI levels in Cairo and Alexandria have dropped during the lockdown months in 2020 by about 30%. Reduction of PM levels during the COVID-19 pandemic has also been observed in several countries/cities including China (Wang and Su, 2020; Wang et al., 2020c), India (Sharma et al., 2020), Rio de Janeiro (Dantas et al., 2020), São Paulo (Nakada and Urban, 2020), Milan (Collivignarelli et al., 2020), Barcelona (Tobías et al., 2020), Nice, Rome, Valencia and Turin (Sicard et al., 2020). The PM emissions in big cities like Cairo has always been reported to be exceeding the national regulations (230 μg/Nm³ for 24-h averaging period) (Huzayyin and Salem, 2013; Hassan and Khoder, 2017; Marchetti et al., 2019).

5.4. Changes in carbon monoxide

Fig. 8 presents the difference in concentrations between 2019 and 2020 (2019 subtracted from 2020). As shown, the CO concentrations in 2020 are less than 2019 in nearly all locations including Cairo and Alexandria. The absolute concentrations are in the range of 120 ppb, so the reduction in CO concentrations in Cairo and Alexandria is about 5%. The decrease in CO emissions is clearly attributed to the less traffic congestion resulting from the partial lockdown policy (Dantas et al., 2020) which should lead to less CO emissions especially from the light-duty vehicles (Heywood, 1998; Pérez-Martínez et al., 2014). Such results seem logic especially that it has been reported in a previous study by the Egyptian Ministry of Environment that the transport sector accounts for about 90% of the CO emissions. In order to assess whether the air pollution levels are more influenced by the partial lockdown compared to the variation in the meteorological conditions, the CO concentrations in 2020 has also been compared to a longer baseline period (2015–2019). As shown in Fig. 9 , the same conclusions were observed where the CO concentrations in nearly all the locations including Cairo and Alexandria have dropped during the lockdown months in 2020 (Cairo and Alexandria also in the range of 5% reduction). Reduction of CO levels during the COVID-19 pandemic has also been observed in several countries/cities including China (Wang and Su, 2020), Southern and Central India (Sharma et al., 2020), Rio de Janeiro (Dantas et al., 2020), São Paulo (Nakada and Urban, 2020), and Milan (Collivignarelli et al., 2020). It was not possible to compare the CO levels to the local environmental limits (30 and 10 mg/Nm³ for 1-h and 8-h averaging period respectively) since the available satellite measured CO concentration data were not available on 1-h or 8-h averaging period.

5.5. Changes in greenhouse gas emissions

One of the main positive environmental impacts of COVID-19 worldwide is the reduction in the greenhouse gas (GHG) emissions. In Egypt specifically, and due to the reduction in fossil fuels and electricity consumption as mentioned above, the GHG emission levels decreased compared to the business as usual scenario. According to Egypt's first biennial update report (BUR) submitted to UNFCCC, the energy sector represents 64.5% of the country's GHG emissions, of which the electricity generation represents 43% and transport represents 23%. In transport, Gasoline fuel nearly represents 38% of the GHG emissions, and Diesel fuel represents 51%. Hence, the consumption of electricity and transport fuels constitute around 43% of the country's GHG emissions. Knowing the percentages reduction in resources consumption during COVID-19 situation (listed above), it can be calculated that Egypt has at least reduced 4% of its GHG emissions. This value is conservative since a lot of other activities has not yet been quantified especially the industrial ones. The global estimates for the potential GHG reductions in 2020 range between 4.5% and 8% (Evans, 2020; Gabbatiss, 2020). It is interesting to note that the current global GHG reduction levels can be considered as a simulation to the efforts needed by all the countries to help achieve the annual 7.6% GHG reduction required to be on the ambitious 1.5 °C global warming pathway.

It worth noting that after noticing the improved air quality and environmental noise, the Egyptian prime minister's cabinet is currently considering to shorten the night working hours of shopping and dining (Egypt Independent, 2020c). This will not only improve the environmental situation of the country, but also impose economic benefits by decreasing the import of fossil fuels (due to the foreseen reduction of energy consumption) and social benefits by allowing the families to spend more time together in the evenings. If such initiative will be really applied, this will be a rare case study for mitigating the expected rebound after the end of the pandemic.

The environmental conventions have always called for decoupling the economic growth from environmental degradation. The results of this research work and the similar ones mainly present the environmental benefits achieved during COVID-19; however, it is clear that this is not sustainable at all due to the acute economic losses associated. In addition, it is expected that the economic crisis that resulted from the COVID-19 pandemic will postpone the investment in clean and innovative technologies; hence, outweighing the environmental benefits achieved during the COVID-19 lockdown period (Gillingham et al., 2020). Moreover, and as was the case with previous economic crisis in 2008, it is estimated that that there will be post-crisis rebound in the emissions (Le Quéré et al., 2020). Hence, all the countries still have a lot of work to do to be effectively on the sustainable economic growth pathway.