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Federal Register / Vol. 86, No. 148 / Thursday, August 5, 2021 / Rules and Regulations
Non-human studies refers to experimental research not performed on people but includes in-vivo and in-vitro studies in animal models, cell lines, and donated human tissue. Such research is particularly useful for determining if specific air pollutants or a mixture thereof is related to respiratory symptoms that might reasonably be seen as precursors to or analogous with the symptoms documented in humans i.e.,
biological plausibility. Initial literature screening was performed by VA SMEs to ensure appropriateness for review as well as assignment to human and nonhuman categories.
Additional SMEs were recruited to critically evaluate the strengths and weakness of evidence using a semiquantitative transparent approach that was based on the Grading of Recommendations Assessment,
Development and Evaluation GRADE
structure. Each reviewing SME was provided with instructions on the overall goals of the review, the PICOTS
framework below as well as instructions on the scoring matrix with the GRADE structure. Each article was evaluated by at least two subject matter experts, and the aggregate results were reviewed by a panel of subject matter experts to derive consensus opinion.

TABLE 2PICOTS FRAMEWORK
PICOTS term
Human studies
Patient Population OR Problem.
Intervention OR Exposure

Adults 1850 years

Relevant model systems e.g., in-vitro, in-vivo.

Chronic exposure to particulate matter PM2.5 air pollution.
No exposure or fine PM levels < federal guidelines
ICD9/10 codes 9 for respiratory conditions and/or biomarkers consistent with these conditions.
Months to years
All countries

Acute/chronic exposure to PM2.5.8

Comparator
Outcomes
Timing
Setting

The 2020 NASEM report reviewed different types of exposures such as open burn pits, emissions from the 2003
Al-Mishraq sulfur plant fire, fuels, oilwell fires, nerve agents, and depleted uranium; regional environmental exposures such as air pollution, particulate matter, biologic agents, and allergens, toxicity of sand and dusts;
and occupational exposures such as vapors, gases, dusts, and fumes. The supplemental review focused on fine particulate matter PM2.5, which is a mixture of solid particles and liquid droplets that have a mean aerodynamic diameter 2.5 microns.10 The focus on PM2.5 was intentional for the following reasons: 1 PM2.5 is generated by a variety of sources including smoke from open burn pits, 2 the DoDs Enhanced Particulate Matter Surveillance Program objectively measured in-theater concentrations and documented concentrations of PM2.5 that may have exceeded military and national exposure guidelines at deployment locations, and 3 its small diameter facilitates greater deposition into the lung and potential for harmful effects. It is recognized that the source of fine particles and their resultant chemical 8 Particulate
matter size of 2.5 microns PM2.5
Health Organization WHO authorized the publication of the International Classification of Diseases 10th Revision ICD10, which was implemented for mortality coding and classification from death certificates. The U.S. developed a Clinical Modification CM ICD10CM for medical diagnoses based on WHOs ICD10. ICD
10CM replaces ICD9CM, volumes 1 and 2.
10 See US EPA, Particulate Matter PM Basics, https www.epa.gov/pm-pollution/particulatematter-pm-basics.

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Non-Human studies
No exposure.
Respiratory condition phenotypes and/or observed behaviors.
Days to months.
Not applicable.

composition are important considerations beyond particle size that should be considered yet there is a paucity of these data.
Based on the observations from many veterans and studies that described particulates in Southwest Asia,11 VA
determined that the levels of particulate matter were high in Southwest Asia and could present a health risk to service members.
II. VAs Findings Post-2020 NASEM
Report Review As previously noted, the VA
Technical Working Group identified knowledge gaps from the 2020 NASEM
report and felt additional review of the literature, of relevance to service members and veterans, was warranted.
In first reviewing the EPAs 2019 ISA on PM2.5, it was noted that the literature reviewed included those articles published through 2017. In addition, the ISA included both children and adults and had a much broader scope. The VAs supplemental review was targeted 11 E.g., SummaryReview of the Department of Defense Enhanced Particulate Matter Surveillance Program ReportNCBI Bookshelf nih.gov; Lindsay T. McDonald et. al, Physical and elemental analysis of Middle East sands from recent combat zones, Am J Ind Med. 2020;63:980987. Inhalation Toxicology, 2020, VOL. 32, NO. 5, 189199. https doi.org/
10.1080/08958378.2020.1766602.; Johann P.
Engelbrecht et al., Characterizing Mineral Dusts and Other Aerosols from the Middle EastPart 1:
Ambient Sampling and Part 2: Grab Samples and Re-Suspensions, Inhalation Toxicology, International Forum for Respiratory Research 2009:4:297326 and 327336, https
www.tandfonline.com/doi/full/10.1080/
08958370802464273 and https
www.tandfonline.com/doi/full/10.1080/
08958370802464299.

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to address these knowledge gaps.
Ultimately, VAs conclusions on respiratory health effects were similar to those of the EPAs 2009 and 2019 ISAs.
The VA committee acknowledges that:
1 There exists a range in the strength of association between PM2.5 exposure and the respiratory conditions of interest, and 2 most of the population epidemiological studies are based upon the assumption that chronic respiratory symptoms are a function of long-term exposure and reductions in ambient concentration lead to resolution of short-term responses, and thus are difficult to apply to the exposure scenario experienced by service members in SW Asia. Therefore, VAs own literature review is not a sufficient basis for concluding that such exposure scenarios would be expected to cause incident or new-onset asthma, sinusitis, and/or rhinitis secondary to exposure.
VA acknowledges that there are important differences between potential exposures experienced by deployed service members and the populations in the studies relied upon by the ISA, and that there are limitations in evidence specific to deployed service members, as discussed above. In the context of regulating potential service connection related to presumed exposure and benefits there is a strong role for policy decisions.12 The Secretarys broad 12 See, e.g., VA, Diseases Associated With Exposure to Certain Herbicide Agents Hairy Cell Leukemia and Other Chronic B-Cell Leukemias, Parkinsons Disease and Ischemic Heart Disease, 75
FR 53202 where there was only limited/suggestive evidence of an association between Ischemic Heart Disease and service and the Secretary exercised his
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