key: cord-1056085-2udiwejn
authors: Othman Aljahdali, Mohammed; Bala Alhassan, Abdullahi; Albeladi, Mutaz N.
title: Impact of Novel coronavirus disease (COVID-19) lockdown on ambient air quality of Saudi Arabia: A case study of nine cities
date: 2020-11-27
journal: Saudi J Biol Sci
DOI: 10.1016/j.sjbs.2020.11.065
sha: 354fea12e75c4a96fef677e834938dafcf552ed7
doc_id: 1056085
cord_uid: 2udiwejn

The outbreak of COVID-19 has spread globally affecting human activities but with improvement in ambient air quality. The first case of the virus in the Kingdom of Saudi Arabia was on the 2nd of March, 2020. The impact of COVID-19 lockdown on the ambient air quality of the Kingdom of Saudi Arabia for the first time using data from nine cities was determined in this study. Hourly air quality data, based on concentrations of carbon monoxide (CO), particulate matter (PM10), sulfur dioxide (SO2), nitrogen dioxide (NO2) and ozone (O3), and meteorological conditions (atmospheric temperature, relative humidity, and wind speed) of the nine cities studied were obtained from Saudi Arabian General Authority of Meteorology and Environmental Protection (GAMEP) for the period between January 2019 to May 2020. Significant variation (p<0.05) was recorded for the five atmospheric pollutants across the cities before and during the lockdown with lower concentrations during the lockdown except for the concentration of O3 in Tabuk, Al Qasim, and Haql. This can be as a result of NO and O3 reaction, causing the inability of effective O3 depletion. The percentage change in concentration for CO (33.60%) and SO2 (44.16%) was higher in Jeddah and PM10 (91.12%) at Riyadh, while NO2 (44.35%) and O3 (18.98%) was highest in Makkah. However, even though there was a decrease in pollutants concentration during the lockdown, the concentrations for CO, PM10, SO2, NO2, and O3 were still above WHO 24 hours and annual mean limit levels. The COVID- 19 lockdown in the Kingdom of Saudi Arabia revealed the possibility of significant atmospheric pollutant reduction by controlling traffic, activities by industries, and environmentally friendly transportation programs such as green commuting programs.

COVID-19 have spread globally and rocketed into one of the largest threat to human health and economic crises of the 21st Century (Briz-Redón et al., 2020; Yu et al., 2020) , leading to its consideration as one of the major disasters ever recorded to affect the modern world (Singh and Chauhan, 2020) . In December 2019, Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) was identified in Wuhan, China. The World Health Organization (WHO) later declared the COVID-19 outbreak as an emergency of public health with international concern on the 30 th of January, 2020 after enforcement of lockdown. The lockdown was enforced by a way of placing the whole city of Wuhan under quarantine on the 23 rd of January, 2020 (WHO, 2020a) . Between February and March 2020, the rise in the number of cases in people and death rates caused by coronavirus was exponentially leading to the enforcement of lockdown in most cities of the world to curb the infection and death rate (Muhammad et al., 2020) . Restriction of human activities including mobility was put in place to control the spread of the virus, this led to a reduction of traffic on the roads, closure of commercial, entertainment, and industrial activities.

Kingdom of Saudi Arabia (KSA) is the second largest country in the Arabian world (Algaissi et al., 2020; GASKSA, 2020) and took early measures to prevent and control the COVID-19 outbreak. In preparation before the outbreak, a national committee was set up in early January 2020 to track worldwide updates and make necessary preparations for any eventual outbreak or spread of the virus. The first case of COVID-19 in KSA was on the 2 nd of March 2020. However, before the first case, an early decision made by the government of KSA as a way of responding to the spread of the virus was through the stoppage of flights coming from China to KSA (Algaissi et al., 2020) . Later on, the government decided to regulate the entrance of individuals from countries with COVID-19 cases to KSA (Barry et al., 2020) . That decision was taken on the 28 th of February, 2020.

Regardless of the measures that were put in place before the first case of COVID-19 in KSA, the cases were still rising at an exponential pattern. When the cases got to 500 towards the end of March 2020, the government of KSA issued a curfew (Badreldin et al., 2020) with a huge penalty of financial type for individuals that refuse to abide by the law.

In the long run, the lockdown in some cities and restrictions on movement between provinces was imposed by the government of KSA (Algaissi et al., 2020) .

The response to The COVID-19 outbreak such as the lockdown of cities has been beneficial to the environment looking at the reduction in atmospheric pollution (Bherwani et al. 2020; . Globally, reports from different studies revealed a decrease in atmospheric pollutions as a result of enforcement of lockdown amidst the COVID-19 outbreak, this is due to a reduction in social and economic activities . Correlation between atmospheric pollution and lockdown due to COVID-19 outbreak or spread has been revealed in many parts of the world. For example, a relationship was established between pollutants such as PM 2.5 , PM 10 , NO 2 , and O 3 with confirmed cases of COVID-19 (Zhu et al., 2020) . Several conclusions were also made in Europe, Asia, Africa, Latin America, and the United States as regards the influence of drastic decrease in anthropogenic activities such as social and economic variables and decline in air pollutants such as PM 10 , PM 2.5 , SO 2 , NO 2 , and O 3 (Muhammad et al., 2020; Nakada and Urban, 2020; Otmani et al., 2020; Xu et al., 2020) .

Our study aims to report the impact of COVID-19 lockdown on the ambient air quality of the Kingdom of Saudi Arabia for the first time using data from nine cities in the kingdom.

Saudi Arabia is the second largest country in the Arabian world with a population of over 34 million with non-indigenes representing about 37% of the population. The population of the country is dominated by the middle age group of 15-64 years while 32.4% and 2.8% are attributed to age groups of 15-64 years and 0-14 years respectively (Algaissi et al., 2020; GASKSA, 2020) . Nine cities namely Makkah (21°22'54.33''N and 39°51'24.29''E), Ha'il (27°30'49.48''N and 41°43'10.76''E), Jeddah (21°29'06.96''N and 39°11'28.82''E), Jazan (16°53'28.23''N and 42°34'12.99''E), Tabuk (28°23'06.66''N and 36°33'58.29''E), Al Madinah (24°31'41.19''N and 39°34'09.06''E), Al Qasim (26°14'05.65''N and 43°29'01.45''E), Riyadh (24°43'21.21''N and 46°40'31.06''E) and Haql (29°17'13.96''N and 34°56'42.54''E) were considered for this study (Figure 1 ). The nine cities considered in this study were selected due to the increased industrial activities and the human population in these cities. This made the populace requirement for the quality of the environment on the increase as a result of the release of pollutants from the industries and automobiles into the atmosphere and their human health consequences.

The lockdown in Saudi Arabia took effect around the ending of March 2020 and was eased on 21 st of June, 2020; as a result, we concluded to carry out this study on the changing pattern of air quality in the months before the lockdown (Jan 2019 to Feb 2020) and the months during the lockdown (March 2020 to May 2020).

Hourly air quality data, based on concentrations of carbon monoxide (CO), particulate matter (PM 10 ), sulfur dioxide (SO 2 ), nitrogen dioxide (NO 2 ) and ozone (O 3 ), and meteorological conditions (atmospheric temperature, relative humidity, and wind speed) of the nine cities studied were obtained from Saudi Arabian General Authority of Meteorology and Environmental Protection (GAMEP) for the period between January 2019 to May 2020. The considered validly of data used was based on hourly concentration above 75% availability (Broomandi et al., 2020) .

Significant variations in atmospheric pollutants (CO, PM 10 , SO 2 , NO 2, and O 3 ) before and during the COVID-19 lockdown across the nine cities studied were determined using One-way analysis of variance (ANOVA): Duncan multiple range test (DMRT). Prior to ANOVA test, the normality of the data was assessed using the Shapiro-Wilk test. Students' t-test was used to test for significant variation in atmospheric pollutants and meteorological conditions each before and during COVID-19 lockdown. The influence of the lockdown period and meteorological conditions on changes in atmospheric pollutants was determined using correlation base Principal component analysis (PCA). IBM SPSS v.22.0 and Minitab v.17 .0 Statistics Software Package were used to analyze the data.

The variation in mean concentrations of atmospheric pollutants before and after COVID-19 lockdown in Saudi Arabia is presented in Tables 1 and 2 Table 3 . Similarity and differences between our results and results reported from some previous studies are shown in (Fig. 2) .

Variations in meteorological conditions such as relative humidity (H), temperature (T), and wind speed (WS) before and during COVID-19 lockdown, are presented in Table   5 . Generally, there was no obvious change or variation between the values for meteorological conditions (Humidity, temperature, and wind speed) between prelockdown (Jan 2019 to Feb 2020) and the COVID-19 lockdown period (March 2020 to May 2020).

Students' t-test (p < 0.05) revealed no significant variation between meteorological conditions before lockdown and lockdown period for the nine cities under study, except for Jeddah where significant variation was observed in relative humidity (Table 4) .

Principal component analysis (PCA) biplot for atmospheric pollutants and meteorological conditions in nine cities of Saudi Arabia studied before the lockdown and during the lockdown period is presented in Figure 3 . Component 1 and 2 accounted for 53.64%, 60.65%, 56.85%, 79.84%, 69.85%, 59.22%, 54.11%, 62.12%, and 56.45% of the total variation in Makkah, Ha'il, Jeddah, Jazan, Tabuk, Al Madinah, Al Qasim, Riyadh, and Haql respectively.

In Makkah, there was an influence of COVID-19 lockdown on PM 10 , CO, and O 3 with also a positive correlation between these three pollutants and temperature. The influence of the lockdown on PM 10 was also recorded in the city of Ha'il, but in contrast, PM 10 was negatively correlated with humidity. The city of Jeddah presents a different situation from Makkah and Ha'il with a lockdown period influencing NO 2 , O 3, and SO 2 with a positive correlation with humidity and wind speed. CO and O 3 were influenced by the lockdown and a negative correlation was established between CO, O 3 , humidity, and wind speed.

For the city of Tabuk, PM 10 , O 3, and SO 2 were revealed to have been impacted during COVID-19 lockdown, besides correlating positively with WS and temperature. In Al Madinah, more importantly, PM 10 was influenced by the introduction of lockdown and also a negative correlation with wind speed and humidity. The lockdown period in the city of Al Qasim had influence PM 10 , CO, O 3 , NO 2, and SO 2 , and revealed a positive correlation between these five atmospheric pollutants and humidity. A negative correlation was also revealed between PM 10 , humidity, and wind speed in Riyadh. However, the impact of the lockdown on PM 10 was also established. A similar outcome was realized in the city of Haql, with the impact of the lockdown on PM 10 , but also includes NO 2 and O 3 . Moreover, a negative correlation existed between PM 10 , NO 2, and humidity, and wind speed correlating positively with O 3 .

The decrease in the concentration of CO, PM 10 , SO 2 , NO 2, and O 3 in KSA regarding the nine cities under study are as a result of the COVID-19 lockdown that led to the decrease in pollution emissions from traffic after the outbreak of COVID-19. (Broomandi et al., 2020; Xu et al., 2020b) . Usually, a negative correlation exists between O 3 and NO x . Factors that influence O 3 accumulation in the atmosphere are the principal chemistry that exists between the concentration of O 3 and emissions due to human activities. For example, NO x in an environment with low VOC together with meteorological conditions (Broomandi et al., 2020; Jain and Sharma, 2020) . Their studies were to assess the impact of COVID-19 lockdown on atmospheric pollutants when compared with the pre-COVID-19 lockdown.

Even though there was a decrease in pollutants concentration during the lockdown, the concentrations for CO, PM 10 , SO 2 , NO 2, and O 3 were still above WHO 24 hours and annual mean limit levels. This confirms non-traffic source emission contributing to an increase in atmospheric pollutants. This can be stationary sources from the industries with the combustion of fossil fuel playing a key role in the complex source mix (Halek et al., 2004) . Kerimray et al. (2020) report similar findings in Almaty, stating the reason for pollutants exceeding levels of WHO during the COVID-19 lockdown due to contribution by non-traffic sources. A study similar to our work was carried out in Eastern China with a reported result revealing a significant decrease of 30 % and 20% in concentrations for NO 2 and CO respectively. It was attributed to reduced anthropogenic activities link to urban transportation and growth in the economy during the period of COVID-19 lockdown (Filonchyk et al., 2020) .

In another study in Iran on the impact of COVID-19 event on the air quality of 12 locations reports a total reduction of -13%, 11.33%, -12.5%, -13%, and +3% for CO, PM 10 , SO 2 , NO 2, and O 3 respectively (Broomandi et al., 2020) . Similar findings were also reported by Xu et al. (2020a) with reduction of 46.5%, 48.9%, 52.5%, 36.2%, and 52.8% for PM 2.5 , PM10, SO 2 , CO, and NO 2 in their study in Anhui Province, close to central China with insight to atmospheric pollutants concentrations during COVID-19 lockdown in three cities (Table 3) .

Non-significant variation recorded between meteorological conditions before the lockdown and during the lockdown indicates meteorological conditions alone not to be the major reason for atmospheric pollution decline during the lockdown period (Navinya et al., 2020; Schiermeier, 2020) . However, significant variation in relative humidity recorded in Jeddah can be as a result of the warm sea close to Jeddah and the rise in temperature linked with the time of the season as the lockdown period with the increase in humidity falls between spring and summer seasons. Properties such as solar radiation and temperature have been reported to contribute to the causation of an increase in the percentage of relative humidity in the atmosphere (Jasaitis et al., 2016; Patlakas et al., 2019) .

Our result agrees with the findings of Navinya et al. (2020) where they report an increase in relative humidity during the COVID-19 lockdown after they examine the effect of the lockdown on ambient air quality of urban setting in India. Patlakas et al. (2019) also report the link between a rise in temperature and relative humidity during spring and summer seasons. Their report captures the aspect of an increase in the variation of regional features as related to Arabian Peninsula climatic conditions. In contrast, Almazroui (2012) gave a different report opposite to our finding of a rise in temperature and relative humidity in spring and summer on their work on dynamical downscaling of rainfall and temperature.

Relationships between the lockdown periods, atmospheric pollutants, and meteorological conditions revealed by PCA can be due to some important phenomena or factors. Phenomenon such as an increase in temperature due to increasing solar radiation during the lockdown period affecting photochemical reactions involved in the formation of O 3 , and also a favorable environment for the accumulation of O 3 (Xu et al., 2020) . While humidity and wind speed have been reported to influence the dispersion of atmospheric pollutants generally (Broomandi et al., 2020) . However, the formation of O 3 in the urban environment involves complex processes with no direct source of emission but produced through reactions involving NOx, CO, and VOCs (volatile organic compounds) which serves as precursors (Biswas et al., 2019; Xu et al., 2020) . The involvement of PM 10 in this relationship is not a coincidence, as it is also produced from factors such as soil dust and sand storms. These are natural and can influence the increase of PM 10 even without other anthropogenic influence, even if the increase is not as rapid or much like before the lockdown (Liu et al., 2020) . This might form a key reason for its positive correlation with temperature and other pollutants during the lockdown period.

Despite the enforcement of lockdown in Saudi Arabia during the period capture in this study, there was a partial activity in some cities by some of the important parastatals such as the petroleum industries. Generally, the enforcement of the lockdown varies with the cities at the beginning of the lockdown. This might have been the cause of SO 2 involvement in some of the relationships and the spread aided by meteorological conditions such as wind speed (Algaissi et al., 2020) . SO 2 are produced mainly from activities of coal and petroleum combustion and smelting of ores containing sulfur. Our result is in line with other literature such as Lokhandwala and Gautam (2020) ; Navinya et al. (2020) , and Xu et al. (2020) .

In this article, the effect of COVID-19 lockdown in the Kingdom of Saudi Arabia on atmospheric pollutants (CO, PM 10 , SO 2 , NO 2, and O 3 ) using data from nine cities was determined. Significant variation (p<0.05) was recorded for the five atmospheric pollutants across the cities before and during the lockdown, with lower concentrations during the lockdown except for the concentration of O 3 in Tabuk, Al Qasim, and Haql. The percentage change in concentration for CO (33.60%) and SO 2 (44.16%) was higher in Jeddah and PM 10 (91.12%) at Riyadh, while NO 2 (44.35%) and O 3 (18.98%) was highest in Makkah.

The significant decrease in atmospheric pollutants during the pandemic captured in this study was due to enforcement of the lockdown which affects industrial production and traffic. A significant change was not recorded in meteorological conditions before and during the lockdown for the nine cities under study except for Jeddah where significant variation was observed in relative humidity. However, even though there was no significant change in meteorological conditions during the lockdown, they still influence changes associated with concentrations of pollutants. The COVID-19 lockdown in the Kingdom of Saudi Arabia revealed the possibility of significant atmospheric pollutant reduction by controlling traffic, activities by industries, and environmentally friendly transportation programs such as green commuting programs. Halek, F., Kavouci, A., Montehaie, H., 2004. Role of motor-vehicles and trend of airborne particulate in the Great Tehran area, Iran. International J. Environ Health Res. 14 (4), 307-313. Table 4 The comparison in the decrease (%) caused by COVID-19 lockdown in some selected studies. (Kerimray et al., 2020) São Paulo -64.80% ---54.30% 30% (Nakada and Urban, 2020) Delhi -30% -60% --53% - (Mahato et al., 2020) (Xu et al., 2020a) 

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