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Numerous epidemiological studies have convincingly demonstrated that exposure to airborne particulate matter (PM) poses a major risk to human health. Southwest Asia, Djibouti and Afghanistan (SADA) are particularly impacted by poor air quality due to several unique phenomenon that result in increased PM concentrations including dust storms, drought, extreme high temperatures, and anthropogenic pollution. Military personnel deployed to US bases in SADA are additionally exposed to sources including open-pit refuse burning, heavy-duty vehicle and aircraft emissions, which can contain toxic metals and organic compounds worsening already high ambient concentrations of PM. As a result, military personnel who have served in the SADA region are particularly at risk for exposure-related health issues.
In a current effort, the Department of Veterans Affairs (VA) aims to examine PM-related respiratory related health effects in 6,200 veterans who were deployed in SADA after 9/11/01. To achieve this goal, the VA has identified the specific locations and durations of deployment of the veterans, to which PM2.5 concentrations will be linked. As ground monitoring in this part of the world is limited, the integration of Earth observations from satellite instruments measuring atmospheric properties is paramount in being able to estimate PM2.5 concentrations.
Our objectives are to build upon the work of the VA to enhance its capabilities to conduct exposure-related health impact assessments and decision-making by 1) integrating new, state-of-the-art satellite and ground data products to estimate size- and source-specific PM exposures in the SADA region and 2) developing and disseminating a software tool that synthesizes these estimates and enables the end-user to create customized location- and time-specific PM exposure histories and source identification.
We will do this by fusing Earth observations of aerosol optical depth (AOD) from the MoDerate resolution Imaging Spectroradiometer (MODIS) Multi-Angle Implementation of Atmospheric Correction (MAIAC) with data from the newly developed 4.4 km aerosol product from the Multi-angle Imaging SpectroRadiometer (MISR). The significance of this is that MISR not only provides AOD, but AOD fractionated by size, shape, and absorption. We will conduct source apportionment using measurements from samplers collecting size-specific PM mass and speciation, supplemented by a set of low-cost PM sensors placed in strategic locations in the study region. These PM sources will be linked with the most representative MISR AOD fractions based on statistical similarity measures. Finally, statistical models will be applied to convert all available AOD and fractional AOD to surface PM2.5 and PM10 mass and source concentrations. The spatially and temporally resolved exposure data created through these steps will be disseminated through a software tool we will develop. Implementation and sustained use of this air quality system makes use of the aforementioned satellite data products and those to be generated from future missions, such as the Multi-Angle Imager for Aerosols (MAIA).
In addition to the VA, we have partnered with two end-users in the Department of Defense: the Center for Deployment Health Research, and the Army Public Health Center. All of our end-users are committed to implementing our PM exposure tool in research and clinical settings, enabling them to make informed decisions about protecting the health of military personnel currently present in SADA or to be sent there in the future. More than 36,000 active-duty individuals from the US are currently deployed in this region.
In light of previous demonstrations, the proposed project is assessed to have an entry Applications Readiness Level (ARL) of 3. By the end of the 3-year period, a standalone decision support system that will be utilized and sustained by the VA and DoD will be implemented, placing the ARL exit level at 8.