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Long-Term Health Consequences of Exposure to Burn Pits in Iraq and Afghanistan (2011)

Chapter: 4 Evaluation of Air Monitoring Data and Determinants of Exposure

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Suggested Citation:"4 Evaluation of Air Monitoring Data and Determinants of Exposure." Institute of Medicine. 2011. Long-Term Health Consequences of Exposure to Burn Pits in Iraq and Afghanistan. Washington, DC: The National Academies Press. doi: 10.17226/13209.
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4

Evaluation of Air Monitoring Data and Determinants of Exposure

The Department of Defense (DoD) has conducted air monitoring studies at Joint Base Balad (JBB) in Iraq in response to complaints by military personnel stationed there that smoke from the burn pit was causing health problems. A recent National Research Council (NRC) report (2010) reviewed the DoD’s Enhanced Particulate Matter Surveillance Program (EPMSP) conducted at U.S. air bases in the Middle East (including JBB) for the U.S. Army’s Center for Health Promotion and Preventive Medicine (CHPPM, now the U.S. Army Public Health Command) (Engelbrecht 2008; Engelbrecht et al. 2009). The NRC report found several limitations in the methodology and study design for the CHPPM study. In 2007 and 2009, CHPPM conducted a series of monitoring campaigns at JBB to measure the concentration of airborne pollutants at several sites on the base. The measurements were used as inputs for risk assessments for potential cancer and noncancer effects that might result from exposure to burn pit emissions (Taylor et al. 2008; CHPPM and AFIOH 2009; USAPHC 2010). The results of these monitoring campaigns are reviewed and further analyzed in this chapter.

In this chapter, the expected sources and nature of air pollutants found at JBB are described based on the location of the base and its operations. This description is followed by a summary of the results of air monitoring carried out at the base; an explanation of the limitations and strengths of the monitoring are provided in Appendix B. The monitoring data are used to compare the average chemical composition of air pollution at different locations on the base to pollution profiles for other locations around the world.

POLLUTANT SOURCES AT JOINT BASE BALAD

Occupants of JBB were and are exposed to a combination of regionally and locally generated air pollutants. Regional air pollutants originate at a considerable distance (miles to thousands of miles) from the exposure location, and may undergo some atmospheric chemical and physical transformations prior to exposure of a receptor. Those pollutants may come from a combination of sources such as industrial activities, mobile sources, and windblown dust. Sources of locally generated air pollutants at JBB include windblown dust, local combustion sources, and volatile evaporative emissions. Local combustion sources include the burn pit or other 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.

At JBB, the high windblown dust concentrations combined with emissions that are combustion derived or from unique regional and local sources offer an unusual mixture of exposures. The particulate matter (PM; pri-

Suggested Citation:"4 Evaluation of Air Monitoring Data and Determinants of Exposure." Institute of Medicine. 2011. Long-Term Health Consequences of Exposure to Burn Pits in Iraq and Afghanistan. Washington, DC: The National Academies Press. doi: 10.17226/13209.
×

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

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1The committee was not provided with any information on how these burn rates were estimated.

Suggested Citation:"4 Evaluation of Air Monitoring Data and Determinants of Exposure." Institute of Medicine. 2011. Long-Term Health Consequences of Exposure to Burn Pits in Iraq and Afghanistan. Washington, DC: The National Academies Press. doi: 10.17226/13209.
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image

FIGURE 4-1 Sampling points and wind rose at JBB. The length of the vanes in the wind rose corresponds to the fraction of time the wind blows from the direction of the vane. This diagram does not correspond in shape or orientation to the layout found in the aerial photos (from 2004) in Google Earth. Obtaining even approximate correspondence requires a rotation and skewing of this diagram. In particular, the location and size of the burn pit, pointed out to the committee by an Air Force contractor and visible on Google Earth imagery, does not correspond (even after rotation and skewing) to the location or size shown on this diagram. The committee is therefore unclear on the exact locations of the sampling sites relative to the burn pit.
SOURCE: Taylor et al. (2008).

2007. [NOTE: There appears to have been sporadic air sampling during 2006; the committee was furnished with some results of 2006 sampling for dioxins but does not know the specific location or exact methodology used.]

The air monitoring approach included fixed site samplers that were placed at the mortar pit (selected to be upwind of the burn pit), at the H-6 housing and CASF sites, and at the guard tower and transportation field sites (chosen to be downwind of the burn pit) (Taylor et al. 2008). No measurements were taken in close proximity to the burn pit. Sampling sites near each other were combined in the 2007 data available to the committee, so that samples were identified as being collected at the mortar pit, the guard tower/transportation field, or H-6 housing/CASF. The 2009 data available to the committee were provided for the five distinct sampling sites shown on Figure 4-1. However, there are no simultaneous samples available to the committee that allow comparison between the guard tower and transportation field sites, or between the H-6 housing and the CASF site. Therefore, the committee combined the data for the guard tower and transportation field sites, and for the H-6 housing and CASF sites, treating each combination of sites as an individual sampling location.

Suggested Citation:"4 Evaluation of Air Monitoring Data and Determinants of Exposure." Institute of Medicine. 2011. Long-Term Health Consequences of Exposure to Burn Pits in Iraq and Afghanistan. Washington, DC: The National Academies Press. doi: 10.17226/13209.
×

The intended sampling period for all samples was 24 hours, with variation due to the logistics of the sampling operation. No information was available to correlate burn pit operations with measurement times. Individual measurement data were provided in the form of Excel files containing sampling data including sample identifiers, sampling locations (2007 data) or sites (2009 data), sampling times, a few observational field notes, and the individual analytical results for each sample.

Although the samples were tested for a large number of air pollutants, there were a number of air pollutants that were not measured because they were not targeted by the analytical methods used. Notably, this study did not include ozone, carbon monoxide, nitrogen dioxide, or sulfur dioxide, which are criteria pollutants in the United States. Furthermore, many air pollutants that are potentially important in burn pit emissions, such as endotoxins or other biological materials, are rarely monitored and samples were not tested for these substances.

The committee requested and received certain meteorological information from the DoD. Ground-level meteorological measurements are taken regularly at JBB, and CHPPM provided hourly information largely conforming2 to METAR/SPECI record format (USAF 2009) for JBB for all of 2007 and 2009. Figure 4-1 indicates the location of two weather stations at JBB. The data files suggest a third weather station location on base (the location specified in the file does not correspond with either location shown in Figure 4-1), but none of the meteorological information is particularly location specific. Upper-air sounding data were not available for JBB3; however, data were available for Al Asad Air Base, Baghdad; Forward Operating Base Kalsu; Q-West; and Al Taqaddum.

Ambient sampling data are sufficient to draw some important conclusions, for the following reasons. First, the PAH and PCDD/F data in particular are of high quality, as reflected by the high degree of pollutant concentration correlations among sites for near-simultaneous samples. Second, although the small number and timing of samples does not allow determination of representative annual averages, they provide some information about the magnitude of seasonal variability of pollutant concentrations because they were collected during different seasons. Third, most samples were obtained during near-simultaneous sampling of the three locations (at least during the same day), allowing direct comparisons between the sample locations (although as noted in Appendix B, the lack of complete simultaneity does limit the comparability of samples).

The differences in concentrations between sampling locations at JBB for near simultaneous measurements allows evaluation of the effect of local versus background sources of air pollutants, including some inference as to the contribution of the burn pit. In the following discussion, a local source is defined as one that has a differential impact on the three JBB locations, in contrast with a background or distant source that impacts all JBB sampling locations in the same way. The mortar pit location exhibited the lowest concentrations of many pollutants; based on meteorology data, it was largely upwind of the burn pit and other local base sources. Thus, that location was used as the background location (least impacted by local sources). Concentration differences between the other two locations and the background location reflect the minimum impact of local sources on the guard tower/transportation field and housing/CASF locations (it is the minimum impact since any effect of such local sources on the background location is missed in those differences).

POLLUTANTS IN AMBIENT AIR AT JOINT BASE BALAD

The committee evaluated the CHPPM data for JBB by comparing pollutant concentrations across the site and to other locations identified in the literature, such as Beijing, China. The following section summarizes the approach and major findings of the exposure measurements taken at JBB and Appendix B discusses some of the limitations of these data. Further details on the measurements are given in Taylor et al. (2008), CHPPM and AFIOH (2009), and USAPHC (2010).

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2All runway-related material was omitted, and the sky condition code CLR was replaced throughout by SKC.

3These data are measurements of temperature and pressure as a function of altitude, obtained using radiosonde balloons. The standard procedure is to release two balloons per day at 00:00 and 12:00 UTC (Coordinated Universal Time).

Suggested Citation:"4 Evaluation of Air Monitoring Data and Determinants of Exposure." Institute of Medicine. 2011. Long-Term Health Consequences of Exposure to Burn Pits in Iraq and Afghanistan. Washington, DC: The National Academies Press. doi: 10.17226/13209.
×

Polycyclic Aromatic Hydrocarbons

Figure 4-2 shows the average PAH concentrations observed by location and sampling campaign, using all the samples available at each location (summaries of numbers and location and timing of sampling are given in Appendix B). The overall pattern of relative concentrations remains similar for each of the sampling campaigns, although distorted in Figure 4-2 for Spring 2007 by sampling on different days at the different locations. Comparing concentration averages computed over samples taken on the same days in 2007, PAHs showed a consistent pattern of higher concentrations at the guard tower/transportation field (17/17 PAHs), lower concentrations at the H-6 housing/CASF location (11/17 PAHs, ranging from 0.82 to 1.98 times the mortar pit), and lowest concentrations at the mortar pit. This pattern suggests that the guard tower/transportation location and the H-6 housing/CASF were affected by local sources.

The concentrations in 2009 were slightly lower than 2007, but there were differences between individual PAHs. Total PAHs were unchanged for mortar pit and H-6 housing/CASF, and they were about 30% less than 2007 values for the guard tower/transportation field.

Table 4-1 compares concentrations of PAHs at JBB with several urban locations and near or downwind of an open burning site. The concentrations measured in polluted urban areas are generally higher than the concentrations observed at JBB for most PAHs.

Particulate Matter and Metals

The JBB site, like much of the Middle East, is characterized by high concentrations of PM10 that are associated with windblown dust and other local and regional sources. The EPMSP found that the CHPPM 1-year Military Exposure Guideline values of 50 µg/m3 for PM10 and 15 µg/m3 for PM2.5 were exceeded at all 15 air sampling sites in the Middle East (including JBB) for the entire 1-year air sampling period (Englebrecht et al. 2008).

The air samples taken by CHPPM at JBB in 2007 and 2009 were analyzed for PM10 total mass and 10 metals (antimony, arsenic, beryllium, cadmium, chromium, lead, manganese, nickel, vanadium, and zinc) within the PM10 sample. The average of the 90 PM10 measurements at JBB in 2007 was 126 µg/m3 (range 2–535 µg/m3); the 24-hour U.S. National Ambient Air Quality Standard (NAAQS)4 of 150 µg/m3 for PM10 was exceeded 26 out of 90 times at the three measurement locations. In 2009, the average of the 51 PM10 measurements (excluding those that the committee considered invalid, see Appendix B) was 709 µg/m3 (range 104–9,576 µg/m3) and the NAAQS was exceeded for 49 of the 51 samples. The three highest measured PM10 values (9,576, 2,481 and 1,951 µg/m3) occurred on the same day during a sandstorm (USAPHC 2010). The corresponding simultaneously measured PM2.5 concentrations were 2,662 µg/m3, not available, and 2,889 µg/m3 (but see Appendix B regarding measurement artifacts). There was no statistically significant difference in the average concentrations of PM10 or PM2.5 among sample locations at JBB, most likely because regional contributions of windblown dust contribute the majority of the material. As discussed in Appendix B, the metal measurements were mostly “none detected,” and they were not considered further by the committee.

The composition of PM was not measured in the CHPPM studies at JBB. The previous DoD EPMSP study (Engelbrecht 2008; Engelbrecht et al. 2009) attempted to measure the composition of PM at several locations in the Middle East, including at JBB and at a site near Baghdad. That study characterized PM at different sampling locations at JBB than those used by CHPPM (NRC 2010). The composition reflected a unique mixture of air pollutants and consisted of substantial amounts of windblown dust combined with elemental carbon and metals that arise from transportation and industrial activities. However, a major problem was identified in the measurements of organic carbon, rendering those results unreliable. Further, an NRC review of the EPMSP cautioned that the measurement methods used for total PM mass were subject to artifacts, that the elemental carbon results might also be affected by the problem that invalidated the organic carbon measurements, and that the x-ray fluorescence measurements of individual elements were insufficiently described to give confidence in the accuracy of the results

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440 CFR Part 50. See http://www.epa.gov/air/criteria.html. To meet the standard, the 24-h PM10 should not exceed 150 µg/m3 more than once per year on average in a 3-year period. Moreover, as pointed out in NRC report (2010), the sampling methodology used at JBB does not correspond to that required for evaluation of NAAQS compliance.

Suggested Citation:"4 Evaluation of Air Monitoring Data and Determinants of Exposure." Institute of Medicine. 2011. Long-Term Health Consequences of Exposure to Burn Pits in Iraq and Afghanistan. Washington, DC: The National Academies Press. doi: 10.17226/13209.
×

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FIGURE 4-2 Mean PAH concentrations at the three sampling locations: guard tower/transportation field (red), H-6 housing/CASF (green), and mortar pit (blue) at JBB. Error bars are standard error of the mean (SEM). The y-axis scale is identical on all three panels, despite the different maximums. Naphthalene is shown separately to avoid scaling problems.

Suggested Citation:"4 Evaluation of Air Monitoring Data and Determinants of Exposure." Institute of Medicine. 2011. Long-Term Health Consequences of Exposure to Burn Pits in Iraq and Afghanistan. Washington, DC: The National Academies Press. doi: 10.17226/13209.
×

TABLE 4-1 Average Measured PAH Concentrations (ng/m3) at JBB Compared with Measurements at Other Locations

Analyte JBB averagea Rome airport apronb Open burning of joss paperc Araraquara City during sugar cane burningd Hong Konge
Urban Industrial
Onsite Down wind Particulate phase only (PM10)
Acenaphthene 3.2 3102.4 140.3 41.3 0.7 n.d. n.d.
Acenaphthylene 9.4 9.7 512.0 104.3 1.0 n.d. n.d.
Anthracene 2.4 1.5 89.4 41.7 0.3 0.1 0.2
Benz[a]anthracene 1.3 1.5 39.8 30.6 n.d. 1.1 0.6
Benzo[a]pyrene 1.3 0.4 21.7 36.9 1.9 2.1 1.3
Benzo[b]fluoranthene 2.7 56.4 26.7 11.0 5.2
Benzo[e]pyrene 1.5 0.5 148.4 74.7 2.7
Benzo[g,h,i]perylene 1.8 1.9 8.5 2.9 1.2
Benzo[k]fluoranthene 0.6 18.8 14.5 0.4 0.3
Chrysene 2.2 1.1 55.8 20.7 6.6 3.4 2.0
Dibenz[a,h]anthracene 0.3 0.0 n.d. 8.0 3.2
Fluoranthene 6.3 2.9 26.0 15.9 3.3 4.8 3.6
Fluorene 11.7 10.4 56.9 61.5 0.4 0.2 0.2
Indeno[1,2,3-cd]pyrene 1.6 1.7 8.7 4.9 1.9
Naphthalene 276.5 1812.0 915.9 223.3 0.4 n.d. n.d.
Phenanthrene 24.5 10.4 95.1 29.4 2.9 0.6 0.5
Pyrene 5.2 2.4 27.8 13.3 2.5 5.1 3.9
Number of Samples 107 5 5 5 10 11 31

NOTE: n.d. = no data.
aUnweighted average of locations and sampling periods from Figure 4-2 (see Table B-1, Appendix B). The JBB average and the other measurements summarized here are not necessarily representative of long-term averages.
bCavallo et al. (2006).
cRau et al. (2008).
dGodoi et al. (2004).
eGuo et al. (2003).

(NRC 2010). Since the same artifacts affect the PM10 and PM2.5 measurements taken at JBB, and since the measurements of metals were too insensitive (Appendix B) to provide useful results, the committee did not attempt to further analyze the PM and metals measurements.

Despite the potential artifacts in measurement, the PM levels measured at JBB are high compared with those found in the United States and in most urban and remote areas. For example, the EPA reports that in the United States during 2009 (the latest year for which data are available), 24-hour mean PM2.5 concentrations were 9.9 µg/m3 and mean PM10 concentrations were 50.3 µg/m3, based on 724 and 310 nationwide monitoring sites, respectively (available at http://www.epa.gov/airtrends/pm.html; accessed March 12, 2011). In Tehran, Iran, warm season mass concentrations for PM10 were 97.6 µg/m3 (range 76.7–122.3 µg/m3), and 25.3 µg/m3 for PM2.5 (range 17.7–34.1 µg/m3) (Halek et al. 2010). In Kuwait, summer daily average concentrations for PM10 were 136.4 µg/m3 (range 41.2–436.2 µg/m3) and 55.6 µg/m3 for PM2.5 (range 17.6–304.4 µg/m3) (Brown et al. 2008). Summer daily average concentrations for 2009 in Chennai, India were 76.0 ± 43.2 µg/m3 for PM10 and 42.2 ± 19.8 µg/m3 for PM2.5 (Srimuruganandam and Nagendra 2011). Additionally, in assessing air quality in the Middle East, Engelbrecht et al. (2009) found elevated levels of PM2.5 at sites where U.S. military personnel are deployed relative to five urban areas in the United States with similar climate conditions: Las Vegas, Los Angeles, Tucson, Albuquerque, and El Paso.

The conclusions suggest that the pollutants of greatest concern at JBB may be the mixture of regional background and local sources—other than the burn pit—that contribute to high PM.

Suggested Citation:"4 Evaluation of Air Monitoring Data and Determinants of Exposure." Institute of Medicine. 2011. Long-Term Health Consequences of Exposure to Burn Pits in Iraq and Afghanistan. Washington, DC: The National Academies Press. doi: 10.17226/13209.
×

Volatile Organic Compounds

Figure 4-3 presents average concentrations of the 12 most frequently detected VOCs by location and sampling campaign, with nondetects assumed to contribute one-half the detection limit (for these VOCs, setting nondetects to zero alters the average estimates by factors between 1 and 2.4). As for PM10, VOC concentrations were similar for many analytes at all the measurement locations at JBB, and there did not appear to be any consistent gradients in concentration, although differing gradients exist for some analytes at some times. This suggests that the regional background is the most important source of VOCs with intermittent local sources providing varying gradients. Table 4-2 compares the concentrations of VOCs at JBB to urban areas and reported in the literature, although some of these measurements are not directly comparable owing to different sampling methods, sampling periods, and limitations in times of day, week, or year sampled. VOC concentrations at JBB are, in general, substantially lower than polluted urban areas outside the United States.

Polychlorinated Dibenzo-Para-Dioxins/Furans

Mean concentrations for PCDD/Fs (Figure 4-4) were calculated for each of the three locations by sampling campaign. Mean concentrations of PCDDs vary considerably by site, and the differences are more pronounced than for PAHs. This spatial heterogeneity is indicative of the presence of local sources affecting these sites. PCDD/F concentrations were highest at the guard tower/transportation field location, the closest sampling location to the burn pit and downwind from it, suggesting the burn pit as a major source of PCDDs/Fs. The H-6 housing/CASF location was less affected, with PCDD/F concentrations three to four times lower than those observed at the guard tower/transportation location. The mortar pit, where individual congener concentrations were 5 to 13 times lower than those found for the guard tower/transportation field, was least affected by the PCDD/F source(s).

Table 4-3 compares the concentrations at the three JBB locations with those for an urban site in Beijing, China. On average, the concentrations at the guard tower/transportation field and H-6 housing/CASF sites were considerably higher than those reported for Beijing. In contrast, the PCDD/F concentrations observed at the mortar pit background location were similar to or lower than those reported for Beijing. The comparisons in Table 4-3 include only one external study because few published studies report all the 2,3,7,8-substituted PCDD/F congeners. The majority of such studies report data in 2,3,7,8-TCDD toxic equivalent concentration units (I-TEQ 1989—International Toxicity Equivalents, 1989 method, with Toxic Equivalency Factor [TEF] given in Table 4-4).5

Table 4-5 shows TEQ values averaged over the three sampling campaigns (Spring 2007, Fall 2007, and 2009) for each of the three JBB sites, and compares them with values from a variety of environments around the world. TEQ values determined for the guard tower/transportation field and H-6 housing/CASF sites are considerably higher than those reported in other environmental studies, except for a landfill fire in Zagreb, Croatia. Finally, the average TEQ value estimated for the mortar pit site was seven times lower than the one determined for the guard tower/field and somewhat lower than that obtained for the Beijing urban site, but higher than values reported for most rural and suburban environments around the world.

There are significant differences in total PCDD/F concentration measurements between the three sampling locations in 2007 (see Table 4-5); the guard tower/transportation field total PCDD/F concentration is 7.5 times the mortar pit concentration, and the H-6 housing/CASF total PCDD/F concentration is 2.5 times the mortar pit concentration. In the 2009 measurements, the total PCDD/F concentrations are decreased by differing factors from 2007; the guard tower/transportation field total PCDD/F concentration is only 30% of that in 2007, while the H-6 housing/CASF and mortar pit total PCDD/F concentrations are 65% of their values in 2007. Also, the guard tower/transportation field total PCDD/F concentration is about 5 times the mortar pit concentration and the H-6 housing/CASF total PCDD/F concentration is still about 2.5 times the mortar pit concentration.

Table 4-5 shows that the measured average concentrations fall with the estimated burn rate, although they are not proportional to the burn rates. However, such lack of proportionality is not surprising in view of the large

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5The I-TEF values have since been updated, but the 1989 version is used here to allow comparison with the literature. Generally, congener distributions are not published so the committee could not recalculate to more recent TEF values.

Suggested Citation:"4 Evaluation of Air Monitoring Data and Determinants of Exposure." Institute of Medicine. 2011. Long-Term Health Consequences of Exposure to Burn Pits in Iraq and Afghanistan. Washington, DC: The National Academies Press. doi: 10.17226/13209.
×

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FIGURE 4-3 Mean VOC concentrations at the three sampling locations: guard tower/transportation field (red), H-6 housing/CASF (green), and mortar pit (blue) at Joint Base Balad.
NOTE: Nondetects are treated as one-half the detection limit; error bars are SEM. The y-axis scales are identical on the three panels, despite their different maximums.

Suggested Citation:"4 Evaluation of Air Monitoring Data and Determinants of Exposure." Institute of Medicine. 2011. Long-Term Health Consequences of Exposure to Burn Pits in Iraq and Afghanistan. Washington, DC: The National Academies Press. doi: 10.17226/13209.
×

TABLE 4-2 Comparison of Average Measured Concentrations (mg/m3) of the 12 Most Frequently Detected VOCs at JBB with Other Locations

Analyte JBBa Taiwanb Bangkok, industrial-commercialc Bangkok, commercial-residentialc Karachi, urband Karachi, roadsided Athens centere Los Angeles, CAf
Benzene 5.4 4.2 56.0 25.0 16.7 63.1 16.0 1.6
Acetone 22.9 nm nm nm nm nm nm 21.1
Chloromethane 1.6 nm nm nm 5.6 4.0 nm nm
Dichlorodifluoromethane 2.8 nm nm nm 3.2 4.7 nm nm
Toluene 18.6 27.6 279.0 72.0 26.8 166.3 54.1 5.4
Hexane 8.9 2.5 68.0 40.0 26.5 251.0 5.7 nm
Total Xylenes 15.3 11.3 150.0 73.0 18.3 200.4 68.8 4.3
Ethylbenzene 4.1 5.2 27.0 13.0 nm nm 11.8 0.9
n-Heptane 3.2 nm 53.0 24.0 16.0 160.3 9.9 nm
1,2,4-Trimethylbenzene 6.0 12.8 28.0 14.0 4.9 32.1 19.2 nm
Propylene 2.5 9.5 nm nm 9.5 67.3 6.7 nm
Methylene chloride 7.4 nm nd nd 1.1 0.6 nm 1.1
Number of samples 122 40 1 1 50 28 12 29

NOTE: nd = not detected; nm = not measured.
aUnweighted average across locations and times from Figure 4-3 (see Table B-3, Appendix B). The JBB average and the other measurements summarized here are not necessarily representative of long-term averages.
bHsieh and Tsai (2003).
cKungskulniti and Edgerton (1990).
dBarletta et al. (2002).
eMoschonas and Glavas (1996).
fCARB (2009).

variability observed in emissions from open burning (Lemieux et al. 2003, 2004) and the possibility that the waste streams differed between those time periods.

SUMMARY AND IMPLICATIONS FOR EXPOSURE

Ambient air concentrations of PCDD/Fs, PAHs, VOCs, and PM were measured at JBB, and the committee used these values to estimate the impact of the burn pit on air pollution at JBB. Of the three monitoring locations at JBB, the mortar pit was considered a background site and was located upwind of the burn pit, the other two locations—H-6 housing/CASF and the guard tower/transportation field—were considered to be downwind of the burn pit; the guard tower/transportation field location was closest in proximity to the burn pit. Ambient air data were evaluated for composition and concentration at each of the sites to determine differences that may be attributed to the burn pit or other known sources. Following are the conclusions of these analyses:

  • Background ambient air concentrations of PM at JBB are high, with average concentrations above the U.S. air pollution standards. The high background PM concentrations are most likely derived from local sources, such as traffic and jet emissions as well as regional sources, including long-range anthropogenic emissions and dust storms, although emissions from the burn pits may contribute a small amount of PM.
  • PCDDs/Fs were detected at low concentrations in nearly all samples, and the burn pit was likely the major source of these chemicals. The toxic equivalents of the concentrations are high compared with locations in the United States and even with polluted urban environments worldwide, but they are 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 these pollutants are regional background, ground transportation, stationary power generation, and the JBB airport.
Suggested Citation:"4 Evaluation of Air Monitoring Data and Determinants of Exposure." Institute of Medicine. 2011. Long-Term Health Consequences of Exposure to Burn Pits in Iraq and Afghanistan. Washington, DC: The National Academies Press. doi: 10.17226/13209.
×

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FIGURE 4-4 Mean PCDD/F concentrations (fg/m3) at the three sampling locations by sampling campaign: guard tower/transportation field (red), H-6 housing/CASF (green), and mortar pit (blue) at JBB.
NOTE: Nondetects were treated as one-half the detection limit; error bars are SEM. The y-axis scale is identical on all three panels, despite the different maximums.

Suggested Citation:"4 Evaluation of Air Monitoring Data and Determinants of Exposure." Institute of Medicine. 2011. Long-Term Health Consequences of Exposure to Burn Pits in Iraq and Afghanistan. Washington, DC: The National Academies Press. doi: 10.17226/13209.
×

TABLE 4-3 Measured PCDD/F Concentrations (fg/m3) at JBB Compared with Beijing, China

Congener ITEF/89a 2006 Guard tower/transportation field H-6 Housing/CASF 2007 Mortar pit
Spring 2007 Fall 2007 2009 Spring 2007 Fall 2007 2009 Spring 2007 Fall 2007 2009 Beijingb
1,2,3,4,6,7,8-HeptaCDD 0.01 1416 3266 2677 1632 1262 511 460 397 204 152 240
1,2,3,4,6,7,8-HeptaCDF 0.01 1638 2983 2180 1196 1168 523 509 511 294 320 926
1,2,3,4,7,8,9-HeptaCDF 0.01 181 387 244 103 137 107 53 58 59 37 155
1,2,3,4,7,8-HexaCDD 0.1 136 322 228 153 115 39 44 42 19 16 19
1,2,3,4,7,8-HexaCDF 0.1 1361 2697 2047 1028 982 467 386 440 232 209 241
1,2,3,6,7,8-HexaCDD 0.1 290 755 500 380 241 88 109 92 38 29 38
1,2,3,6,7,8-HexaCDF 0.1 487 962 739 323 362 192 137 170 95 78 237
1,2,3,7,8,9-HexaCDD 0.1 428 1623 870 553 404 133 127 124 49 37 28
1,2,3,7,8,9-HexaCDF 0.1 37 54 80 28 28 23 14 11 14 12 90
1,2,3,7,8-PentaCDD 0.5 192 434 282 170 153 56 41 50 22 18 23
1,2,3,7,8-PentaCDF 0.05 365 730 725 168 263 165 71 119 60 47 151
2,3,4,6,7,8-HexaCDF 0.1 594 1187 762 539 449 199 181 184 96 85 305
2,3,4,7,8-PentaCDF 0.5 629 1000 1001 378 406 250 153 202 112 78 249
2,3,7,8-TetraCDD 1 58 118 126 117 39 35 37 11 15 8 7
2,3,7,8-TetraCDF 0.1 260 493 497 135 217 107 59 103 58 45 144
OctaCDD 0.001 1338 3006 3887 1258 1279 719 486 360 354 384 602
OctaCDF 0.001 636 1286 751 271 471 255 181 187 229 173 902
TEQ/89 880 1752 1431 745 639 333 254 270 151 115 275

NOTE: ITEF = International toxicity equivalency factor; TEQ = toxic equivalent.
aEPA (1989).
bLi et al. (2008).

Suggested Citation:"4 Evaluation of Air Monitoring Data and Determinants of Exposure." Institute of Medicine. 2011. Long-Term Health Consequences of Exposure to Burn Pits in Iraq and Afghanistan. Washington, DC: The National Academies Press. doi: 10.17226/13209.
×

TABLE 4-4 PCDD/F Concentrations in TEQ Units at JBB in 2007 Compared with Other Locations


Location fg I-TEQ/m3
(I-TEQ/89 method)
Reference

Balad, Guardtower/Transportation Field    1,309  
Balad, H-6 Housing/CASF       409  
Balad, Mortar Pit       179  
Catalonia, Spain, industrial, 1994–2004       140 1
Catalonia, Spain, rural, 1994–2004         28 1
Athens, Greece, background, July 2000           8 1
Catalonia, Spain, traffic, 1994–2004         72 1
Beijing, China, 3 districts, Feb–Dec 2006       275 1
Athens, Greece, urban, July 2000         42 1
Porto, Portugal, Suburban, 1999–2004       149 1
Lisbon, Portugal, Suburban, 1999–2004         34 1
Madeira, Portugal, rural, 1999–2004         15 1
Zagreb, Croatia, May 1997–March 2000         61 2
Zagreb, Croatia, during garden waste fire         90 2
Zagreb, Croatia, during landfill fire  13,200 2

NOTE: The JBB averages and the other measurements summarized here are not necessarily representative of long-term averages. References are (1) Li et al. (2008), and (2) Krauthacker et al. (2006).

TABLE 4-5 Average Total 2,3,7,8-PCDD/F Concentrations (Sum of All 2,3,7,8 Congeners, in fg/m3) by Sampling Location and Period

Sampling Date Burn Rate at Pit, tons* Guardtower/ Transportation Field H-6 Housing/ CASF Mortar pit
Spring 2007 100–200 21,303 7,975 3,063
Fall 2007 50–100 17,593 3,868 1,949
2009 10 8,434 3,047 1,727

*USAPHC (2010).

These conclusions are based on the measurements available, but those measurements omitted some of the pollutants considered criteria pollutants in the United States, such as sulfur dioxide, ozone, nitrogen dioxide, and carbon monoxide. Since the burn pit is likely to have been a source of some of those pollutants, the evaluation of air monitoring data alone cannot provide a complete picture of the potential effects of burn pit emissions. Furthermore, there likely were additional pollutants emitted from the burn pit that were not measured during the CHPPM monitoring campaigns, since the burning of household waste is known to emit other pollutants (EPA 1997, 2001; Lemieux et al. 2003, 2004). Various modeling efforts were undertaken by the committee to examine the consistency of its conclusions, including air dispersion modeling, PMF analysis, and scale-up from emissions observed in experimental burning of household waste in barrels. These modeling efforts were largely consistent with the committee’s conclusions, although they were limited by the available data. However, it is unlikely that the measurements presented here misrepresent the general trend of low contributions of emissions from the burn pit at the monitoring sites at JBB. The potential health risks associated with these exposures are discussed further in Chapter 5.

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Suggested Citation:"4 Evaluation of Air Monitoring Data and Determinants of Exposure." Institute of Medicine. 2011. Long-Term Health Consequences of Exposure to Burn Pits in Iraq and Afghanistan. Washington, DC: The National Academies Press. doi: 10.17226/13209.
×

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Suggested Citation:"4 Evaluation of Air Monitoring Data and Determinants of Exposure." Institute of Medicine. 2011. Long-Term Health Consequences of Exposure to Burn Pits in Iraq and Afghanistan. Washington, DC: The National Academies Press. doi: 10.17226/13209.
×

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Suggested Citation:"4 Evaluation of Air Monitoring Data and Determinants of Exposure." Institute of Medicine. 2011. Long-Term Health Consequences of Exposure to Burn Pits in Iraq and Afghanistan. Washington, DC: The National Academies Press. doi: 10.17226/13209.
×

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Suggested Citation:"4 Evaluation of Air Monitoring Data and Determinants of Exposure." Institute of Medicine. 2011. Long-Term Health Consequences of Exposure to Burn Pits in Iraq and Afghanistan. Washington, DC: The National Academies Press. doi: 10.17226/13209.
×
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Suggested Citation:"4 Evaluation of Air Monitoring Data and Determinants of Exposure." Institute of Medicine. 2011. Long-Term Health Consequences of Exposure to Burn Pits in Iraq and Afghanistan. Washington, DC: The National Academies Press. doi: 10.17226/13209.
×
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Suggested Citation:"4 Evaluation of Air Monitoring Data and Determinants of Exposure." Institute of Medicine. 2011. Long-Term Health Consequences of Exposure to Burn Pits in Iraq and Afghanistan. Washington, DC: The National Academies Press. doi: 10.17226/13209.
×
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Suggested Citation:"4 Evaluation of Air Monitoring Data and Determinants of Exposure." Institute of Medicine. 2011. Long-Term Health Consequences of Exposure to Burn Pits in Iraq and Afghanistan. Washington, DC: The National Academies Press. doi: 10.17226/13209.
×
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Suggested Citation:"4 Evaluation of Air Monitoring Data and Determinants of Exposure." Institute of Medicine. 2011. Long-Term Health Consequences of Exposure to Burn Pits in Iraq and Afghanistan. Washington, DC: The National Academies Press. doi: 10.17226/13209.
×
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Suggested Citation:"4 Evaluation of Air Monitoring Data and Determinants of Exposure." Institute of Medicine. 2011. Long-Term Health Consequences of Exposure to Burn Pits in Iraq and Afghanistan. Washington, DC: The National Academies Press. doi: 10.17226/13209.
×
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Suggested Citation:"4 Evaluation of Air Monitoring Data and Determinants of Exposure." Institute of Medicine. 2011. Long-Term Health Consequences of Exposure to Burn Pits in Iraq and Afghanistan. Washington, DC: The National Academies Press. doi: 10.17226/13209.
×
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Suggested Citation:"4 Evaluation of Air Monitoring Data and Determinants of Exposure." Institute of Medicine. 2011. Long-Term Health Consequences of Exposure to Burn Pits in Iraq and Afghanistan. Washington, DC: The National Academies Press. doi: 10.17226/13209.
×
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Suggested Citation:"4 Evaluation of Air Monitoring Data and Determinants of Exposure." Institute of Medicine. 2011. Long-Term Health Consequences of Exposure to Burn Pits in Iraq and Afghanistan. Washington, DC: The National Academies Press. doi: 10.17226/13209.
×
Page 39
Suggested Citation:"4 Evaluation of Air Monitoring Data and Determinants of Exposure." Institute of Medicine. 2011. Long-Term Health Consequences of Exposure to Burn Pits in Iraq and Afghanistan. Washington, DC: The National Academies Press. doi: 10.17226/13209.
×
Page 40
Suggested Citation:"4 Evaluation of Air Monitoring Data and Determinants of Exposure." Institute of Medicine. 2011. Long-Term Health Consequences of Exposure to Burn Pits in Iraq and Afghanistan. Washington, DC: The National Academies Press. doi: 10.17226/13209.
×
Page 41
Suggested Citation:"4 Evaluation of Air Monitoring Data and Determinants of Exposure." Institute of Medicine. 2011. Long-Term Health Consequences of Exposure to Burn Pits in Iraq and Afghanistan. Washington, DC: The National Academies Press. doi: 10.17226/13209.
×
Page 42
Suggested Citation:"4 Evaluation of Air Monitoring Data and Determinants of Exposure." Institute of Medicine. 2011. Long-Term Health Consequences of Exposure to Burn Pits in Iraq and Afghanistan. Washington, DC: The National Academies Press. doi: 10.17226/13209.
×
Page 43
Suggested Citation:"4 Evaluation of Air Monitoring Data and Determinants of Exposure." Institute of Medicine. 2011. Long-Term Health Consequences of Exposure to Burn Pits in Iraq and Afghanistan. Washington, DC: The National Academies Press. doi: 10.17226/13209.
×
Page 44
Suggested Citation:"4 Evaluation of Air Monitoring Data and Determinants of Exposure." Institute of Medicine. 2011. Long-Term Health Consequences of Exposure to Burn Pits in Iraq and Afghanistan. Washington, DC: The National Academies Press. doi: 10.17226/13209.
×
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Suggested Citation:"4 Evaluation of Air Monitoring Data and Determinants of Exposure." Institute of Medicine. 2011. Long-Term Health Consequences of Exposure to Burn Pits in Iraq and Afghanistan. Washington, DC: The National Academies Press. doi: 10.17226/13209.
×
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Many veterans returning from the conflicts in Iraq and Afghanistan have health problems they believe are related to their exposure to the smoke from the burning of waste in open-air "burn pits" on military bases. Particular controversy surrounds the burn pit used to dispose of solid waste at Joint Base Balad in Iraq, which burned up to 200 tons of waste per day in 2007. The Department of Veterans Affairs asked the IOM to form a committee to determine the long-term health effects from exposure to these burn pits. Insufficient evidence prevented the IOM committee from developing firm conclusions. This report, therefore, recommends that, along with more efficient data-gathering methods, a study be conducted that would evaluate the health status of service members from their time of deployment over many years to determine their incidence of chronic diseases.

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