Investigations on PM₁₀, PM_2.5, and Their Ratio over the Emirate of Abu Dhabi, United Arab Emirates

Worldwide monitoring of ambient outdoor air quality is critical for planning mitigation measures and controls for public safety. Several airborne pollutants are measured and continuously monitored by multiple government environmental agencies. Such pollutants include particulate matter (PM) levels, both PM₁₀ and PM_2.5, ozone, nitrogen dioxide, sulfur dioxide, carbon monoxide, lead, and volatile organic compounds. However, scientific studies related to air pollution and the temporal variability of PM levels in the United Arab Emirates are limited. This study comprehensively analyzes the spatiotemporal variations in PM₁₀, PM_2.5, and the PM_2.5/PM₁₀ ratio over the Emirate of Abu Dhabi in the United Arab Emirates during 2017–2018. The PM levels are high during April–September, peaking in July each year, likely because of intense dust and sandstorms; the same levels are low during October–March. Industrial areas have higher annual average PM₁₀ levels (162 μg/m³) compared to urban core areas (132 μg/m³) and suburban areas (131 μg/m³). In general, the values of the PM_2.5/PM₁₀ ratio are low ranging between annual averages of 0.29 and 0.49 across the industrial, urban core, and desert/suburban areas. This is a characteristic particular to arid and semi-arid environments owing to the prevalence of high quantities of PM₁₀ leading to a low PM_2.5/PM₁₀ ratio. In addition, this low ratio indicates that, within the Emirate of Abu Dhabi, air pollution is primarily driven by natural processes related to sand particle uplift, movement, and deposition rather than by human activities.