The impact of COVID-19 lockdown on the air quality of Eastern Province, Saudi Arabia

Abstract

Since the identification of the COVID-19 outbreak in Wuhan, China, in December 2019, the death toll from the direct infection by COVID-19 has exceeded 775,000, and more than 21 million cases have been reported to the World Health Organization (WHO) around the world. It is strongly believed that its impact might be worsened by poor outdoor and indoor air qualities, particularly on older adults. The nationwide lockdown measures were imposed between March 23 and June 20, 2020, to stop the spread of COVID-19 pandemic in the Kingdom of Saudi Arabia (KSA). In this work, the possible effects of the lockdown on the air quality were investigated using meteorological and air quality datasets obtained from eight monitoring stations covering the Eastern Province of the KSA. The studied air pollutants include carbon monoxide (CO), sulfur dioxide (SO₂), nitrogen dioxide (NO₂), ozone (O₃), and inhalable particulate matter (PM₁₀). The NO₂ was found to be the marker pollutant responding best to the lockdown measures since its concentrations decreased at all sites during- and post-lockdown periods and ranged between 12-86% and 14-81%, respectively. Compared with pre-lockdown period, the Eastern Province also experienced significant concentration reductions at varying rates for PM₁₀ (21-70%), CO (5.8-55%), and SO₂ (8.7-30%), while O₃ concentrations showed increasing rates ranging between 6.3 and 45%. The consequences of these reductions were reflected in easing the outdoor air quality, which might reduce the impact of COVID-19 pandemic, especially on elderly and sensitive groups.

Keywords: Air pollution; Air quality; COVID-19; Lockdown; Sars-Cov-2; Saudi Arabia.

Fig. 1

Locations of air quality monitoring stations in the Eastern Province

Fig. 2

Wind rose plots for the study region during: a the whole study, b pre-lockdown, c lockdown, and d post-lockdown periods

Fig. 3

Box and whisker plots of daily average CO, SO₂, NO₂, O₃, and PM₁₀ concentrations within the periods of pre-lockdown, during lockdown, and post-lockdown

Fig. 4

Bivariate polar plots illustrating the joint effect of wind velocity and wind direction on observed pollutants at Rakah station

Fig. 5

Percent changes in air pollution levels during COVID-19 pandemic compared with pre-lockdown period