Air quality levels in the industrial city of Jubail, Saudi Arabia

Ambient air quality remains a significant health and environmental challenge in developing cities, primarily due to increasing gas emissions from fossil fuel use. Harmful outdoor air pollutants constitute a critical environmental and public health concern, as poor air quality directly impacts human health, leading to respiratory and cardiovascular diseases. This study aimed to assess ambient gaseous air pollutants—specifically sulfur dioxide (SO 2 ), nitric oxide (NO), nitrogen dioxide (NO 2 ), carbon monoxide (CO), and non-methane hydrocarbons (NMHC)—in Jubail Industrial City, Saudi Arabia. Hourly fixed-site air quality monitoring data were collected from three monitoring stations distributed throughout Jubail, covering the period from January 2020 to December 2022, alongside recorded hourly meteorological conditions. Standard monitoring equipment was employed to measure pollutant concentrations at all three locations. Notably, the highest emissions of CO, SO 2 , and NMHC occurred in 2021, while the highest emissions of NO, NO 2 , and NOx were recorded in 2022, with 2022 generally exhibiting the highest gas emissions and 2020 the lowest. Variations in gaseous contaminants were observed, influenced by changes in meteorological conditions and human activities. However, the levels of gaseous emissions remained within acceptable limits according to the air quality index. Consequently, policies implemented during and after the COVID-19 lockdown effectively reduced the accumulation of gaseous emissions to below harmful levels. Maintaining these measures is crucial for ensuring ongoing air quality improvements.