Spatial and temporal variations in PM2.5 and associated health risk assessment in Saudi Arabia using remote sensing.

Air pollutants, especially ambient particulate matter (PM2.5), detrimentally impact human health and cause premature deaths. The dynamic characteristics and associated health risks of PM2.5 are analyzed based on the standard deviational ellipse (SDE) and trend analysis in Saudi Arabia (SAU) from 1998 to 2018 by utilizing recently updated satellite-derived PM2.5 concentrations (V4.GL.03). The outcomes show that the national average PM2.5 concentration increased from 28 µg/m3 to 45 µg/m3 with a growth rate of 2.3 µg/m3/year. The center of median PM2.5 concentrations moved to the southeast over the years studied due to the presence of vast sandy deserts, sand dunes, a busy port, and coastal and industrial areas in this region. The areas of SAU that experienced PM2.5 concentrations above 35 µg/m3 increased from 20% to 70%. The rapid-fast growth (RFG) class acquired from the unsupervised classification has the fastest growth rate of 2.5 µg/m3/yr, occurring in southeastern SAU, namely Ash-Sharqiyah, Ar-Riyad, and Najran. It covered ∼27% of the total area of SAU over the study period. Whereas, the slow growth (SG) class with a less than 0.2 µg/m3/yr growth rate covered 12% of the total area of SAU, distributed in northwestern regions. The extent of extremely-high risk areas corresponding to greater than 1 × 103 µg·person/m3 increased from 4% to 11%, particularly in Makkah, Central Al-Madinah, and western Asir, Jizan, mid-eastern Najran, Al-Quassim, and mid-eastern Ar-Riyad and Ash Sharqiyah.