marily windblown dust) contains large amounts of geological materials (for example, aluminum silicates, calcium carbonate, and iron oxide) from local soils, carbon that originates mostly from combustion sources, metals from soils, and emissions from a combination of local and regional mobile sources, including smelting activities. The presence of metals in previously collected EPMSP PM samples illustrate the potential for smelting activities and lead from gasoline (lead is still used in gasoline in this area) to contribute to metal concentrations in the air near highly populated areas (Engelbrecht et al. 2009). Gaseous pollutants such as sulfur dioxide and carbon monoxide may originate locally, such as from combustion and ignition engine sources, but pollutants such as ozone may originate regionally and be generated primarily during photochemical transformations.
The major local pollutant sources at JBB include (or included) combustion products from a combination of airport traffic (airplanes and helicopters), ground transportation, stationary power generation (diesel electricity generators), local industry and households, and waste burning associated with incineration (currently) or the burn pit (previously). Each of these sources emits a complex mixture of particulate and gaseous pollutants that include volatile organic compounds (VOCs), particle- and vapor-phase semivolatile organics, metals, and PM.
In accordance with DoD Directive 4140.25 (April 2004), aircraft, ground vehicles and power generators at JBB are mostly fueled by JP-8 jet fuel, a heavy petroleum distillate fuel similar in characteristics to commercial fuel oil (NRC 2003). Vehicles on and around the base are typically not equipped with emissions reduction technology. The PM from vehicles is typically 100 nm or smaller in diameter at the exhaust and is composed of a mixture of elemental and organic carbon that varies with the engine operating conditions, together with traces of metal oxides. Atmospheric transport of vehicle particulate emissions leads to larger particle sizes as the small particles agglomerate, and some of the semivolatile organics emitted as vapors will condense on particles.
The gaseous- or vapor-phase emissions from the sources affecting JBB include nitrogen oxides, ozone, carbon monoxide, sulfur dioxide, and volatile and semivolatile organic compounds. As discussed in more detail below, the volatile hydrocarbons measured at JBB include other hazardous air pollutants such as formaldehyde, benzene, and 1,3-butadiene, while the measured semivolatile hydrocarbons include polycyclic aromatic hydrocarbons (PAHs), and polychlorinated dibenzo-p-dioxins and furans (PCDDs/Fs), all measured so as to capture both vapor-phase and particulate-phase components. There is significant overlap in the composition of emissions from the various sources, making source attribution difficult or impossible based on simple characterization of ambient air composition. Nevertheless, the subtle differences in observed composition between locations on the base were used by the committee in an attempt to estimate the contributions of the hypothesized major sources of pollutants.
JOINT BASE BALAD MONITORING DATA
Figure 4-1 is a map of the basic layout of JBB, including the monitoring sites for the CHPPM screening health risk assessments (Taylor et al. 2008; CHPPM and AFIOH 2009; USAPHC 2010), and the wind rose for 2003 through 2007. Air measurements were taken at the five sampling sites labeled as mortar pit, guard tower, transportation field, H-6 housing, and Contingency Aeromedical Staging Facility (CASF). The wind direction is primarily northwest to southeast. The committee requested from the DoD, but did not receive, more precise relative coordinate information for the sampling sites and the burn pit and more information on the dimensions of the burn pit. The committee was informed by the DoD that it was unable to provide further information on the location of the burn pit until U.S. troops had left the area (Major Scott Newkirk, Army Institute of Public Health, personal communication, October 28, 2010).
The first air monitoring campaign was conducted from January to April 2007. At that time no incinerators were operating on the base and an estimated 200 tons of waste were burned daily in the pit (USAPHC 2010). During the October–November 2007 monitoring campaign, the burn pit burn rate was estimated to be half the spring value (100 tons/day) with two incinerators operating, and 10 tons/day during the May–June 2009 monitoring campaign when three incinerators were operating (USAPHC 2010).1 The incinerators are located at the south end of the site, and emissions from them are not expected to have substantially affected the concentrations measured onsite, at least in
1The committee was not provided with any information on how these burn rates were estimated.