The committee received raw air-monitoring data on JBB from CHPPM to use in its analysis of the expected sources and nature of air pollutants. The monitoring data were used to compare the average chemical composition of air pollution at different locations on the base and with pollution profiles for other locations around the world. Of the three monitoring locations at JBB, one was considered a background site (a mortar pit) that was usually upwind of the burn pit, and the other two locations (H-6 housing/CASF and a guard tower and transportation field) were considered to be downwind of the burn pit.

Sources of regionally and locally generated air pollutants at JBB include windblown dust, local combustion sources, and volatile evaporative emissions. The local combustion sources include the burn pit or incinerators for refuse, compression ignition vehicles, aircraft engines, diesel electric generators, and local industry and households. Volatile evaporative emissions come primarily from refueling and other fuel-management activities on the base. Each of those sources emits a complex mixture of particulate and gaseous pollutants that include volatile organic compounds (VOCs), particle-phase and vapor-phase semivolatile organic compounds, metals, and PM.

Ambient air concentrations of polychlorinated dibenzo-p-dioxins and dibenzo-p-furans (PCDDs/Fs), polyaromatic hydrocarbons (PAHs), and VOCs were measured at JBB, and the committee has used the values to estimate the effect of the burn pit on air pollution at JBB. Sampling data were evaluated for composition and concentration at each of the sites with a goal of determining differences that may be attributed to the burn pit and other known sources. The conclusions of the analyses are as follows:

  • Background ambient-air concentrations of PM at JBB were high, on the average higher than U.S. air-pollution standards. The high background PM concentrations were most likely derived from local sources, such as traffic and jet emissions, and regional sources, including long-range anthropogenic emissions and dust storms, although emissions from the burn pits may have contributed a small amount of PM.
  • PCDDs/Fs were detected at low concentrations in nearly all samples, and the burn pit was probably the major source of these chemicals. The toxic equivalents of the concentrations were higher than those in the United States and even in polluted urban environments worldwide, but they were below those associated locally with individual sources.
  • Ambient VOC and PAH concentrations were similar to those reported for polluted urban environments outside the United States, and the major sources of those pollutants were regional background, ground transportation, stationary power generation, and the JBB airport.

Although many air pollutants were measured, some probably went unmeasured because they were not targeted. Notably, the CHPPM measurement campaigns did not include ozone, carbon monoxide, nitrogen dioxide, or sulfur dioxide—which are criteria pollutants in the United States—or other chemicals associated with combustion, such as hydrogen cyanide. The burn pit is likely to have been a source of such pollutants, so the evaluation of air-monitoring data alone cannot provide a complete picture of the potential effects of burn pit emissions. The committee appreciates the air-monitoring campaigns conducted at JBB and elsewhere in the Middle East, but flaws in the sampling design and protocols prevent a thorough understanding of the nature and sources of the air pollutants detected at JBB. The committee indicates where air-monitoring campaigns might be improved for future efforts.

The committee’s conclusions suggest that the greatest pollution concern at JBB may be the mixture of regional background and local sources—other than the burn pit—that contribute to high PM. This PM, which was characterized in a different study and at different locations at JBB, consists of substantial amounts of windblown dust combined with elemental carbon and metals that arise from transportation and industrial activities. On the basis of the high concentrations in the previous studies of potentially toxic constituents of ambient PM, the air-pollution literature that focused on PM and gaseous pollutant coexposures was considered relevant to the potential morbidity of military personnel at JBB and at other sites in the Middle East.

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