Characterizing Mineral Dusts and Other Aerosols from the Middle East—Part 1: Ambient Sampling

Abstract

The purpose of the Enhanced Particulate Matter Surveillance Program was to provide scientifically founded information on the chemical and physical properties of dust collected over a period of approximately 1 year in Djibouti, Afghanistan (Bagram, Khowst), Qatar, United Arab Emirates, Iraq (Balad, Baghdad, Tallil, Tikrit, Taji, Al Asad), and Kuwait (northern, central, coastal, and southern regions). Three collocated low-volume particulate samplers, one each for the total suspended particulate matter, < 10 μ m in aerodynamic diameter (PM₁₀) particulate matter, and < 2.5 μ m in aerodynamic diameter (PM_2.5) particulate matter, were deployed at each of the 15 sites, operating on a ‘1 in 6’ day sampling schedule. Trace-element analysis was performed to measure levels of potentially harmful metals, while major-element and ion-chemistry analyses provided an estimate of mineral components. Scanning electron microscopy with energy dispersive spectroscopy was used to analyze the chemical composition of small individual particles. Secondary electron images provided information on particle size and shape. This study shows the three main air pollutant types to be geological dust, smoke from burn pits, and heavy metal condensates (possibly from metals smelting and battery manufacturing facilities). Non-dust storm events resulted in elevated trace metal concentrations in Baghdad, Balad, and Taji in Iraq. Scanning-electron-microscopy secondary electron images of individual particles revealed no evidence of freshly fractured quartz grains. In all instances, quartz grains had rounded edges and mineral grains were generally coated by clay minerals and iron oxides.

ACKNOWLEDGEMENTS

We acknowledge contributions by the military public-health soldiers, sailors, and airmen whose efforts were necessary to complete the Enhanced Particulate Matter Surveillance Program (EPMSP). The dedicated effort shown by all participating units in the field, who operated the sampling equipment and collected filter and grab samples, is greatly appreciated. We acknowledge major contributions from the two collaborating laboratories: RTI International, for the filter processing and chemical analysis; and RJ Lee Group Inc. (specifically Traci Lersch), for the CCSEM and SEM individual particle analysis. Thanks are also due to several researchers at DRI who contributed their expertise to the analyses and this report: Micha Skiba for the XRD analysis; Todd Caldwell for analysis of the soil samples; Steve Kohl for the analyses of the re-suspended filter samples, and Dave Campbell for compiling the IMPROVE, CSN, and standards data, and map of the US sampling sites. Finally, the following individuals deserve special recognition for their contributions: Greta Engelbrecht, for data validation, compilation of results, and preparing graphical representations; and James Sheehy and John Kolivosky of USACHPPM, for their support from the inception of the Enhanced Particulate Matter Surveillance Program to its completion. The project was funded under the US Department of Defense contract number W9124R-05-C-0135/SUBCLIN 000101-ACRN-AB.

Notes

1. US Environmental Protection Agency Quality Assurance Guidance Document 2.12—Monitoring PM_2.5 in Ambient Air Using Designated Reference or Class I Equivalent Methods, November 1998.

2. National Institute for Occupational Safety and Health (NIOSH) Method 5040—Elemental Carbon (Diesel Particulate), Issue 3 (interim), September 1999.