Aerosols as Vectors for Contaminants: A Perspective Based on Outdoor Aerosol Data from Kuwait

The Middle East is a hot spot of dust, and there are reports of as much as 1400 mu g m(-3) of dust in aerosols from Kuwait, which is among some of the highest dust loadings globally. A significant volume of literature has emerged on dust-air-quality-human-health, and the World Health Organization in its recent air quality guidelines has lowered the limit of annual PM2.5 exposure to 5 mu g m(-3) from the previous limit of 10 mu g m(-3). We present a mini-review based on a screening and search of the published data generated in Kuwait on contaminants associated with dust in different size fractions. We also include an unpublished study on organic contaminants in size-fractionated aerosols. The Sigma PAHs concentrations in all the six size fractions range between 570 and 3350 pg m(-3). The n-ary sumation Sigma BDE concentration ranges from <- 2 to 1307 pg m(-3). The average Po-210 activity in aerosol size classes varies between 2289 and 2581 Bq kg(-1). The average Pb-210 concentration varies between 352 and 412 Bq kg(-1). The MP inventory in Kuwait's outdoor aerosol is between 5 and 35 MP in 815 +/- 5 m(3) of air. The bacterial load in outdoor aerosols is between 6.05 x 10(3) cells m(-3) and 1.24 x 10(8) cells m(-3). The fungal load ranges between 2.11 x 10(2) cells m(-3) and 2.66 x 10(6) cells m(-3). The data suggest that the inhalable fraction of <2.5 mu m size contains high concentrations of Polycyclic Aromatic Hydrocarbons (PAHs), Polybrominated diphenyl ethers (PBDEs), Po-210, Pb-210, microplastics, and microbes. These enriched ultrafine aerosols pose a significant risk to human health. The review also highlights the scarcity of contaminant data in respirable and inhalable size fractions that are critical for a comprehensive inhalation risk assessment.