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discoveries/houston-aod.discoveries.mdx

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-    Authors: Trent Cowan<sup>[1]</sup>, Brian Freitag<sup>[2]</sup>, Udaysankar Nair<sup>[1]</sup>, Andrew Blackford<sup>[1]</sup>
+    Authors: Trent Cowan<sup>[1]</sup>, Udaysankar Nair<sup>[1]</sup>, Andrew Blackford<sup>[1]</sup>
 
 
     ### Introduction
     <mark>🚧 This Data Story presents work in progress and not peer-reviewed results! 🚧</mark>
 
-    The Houston metropolitan area is the fourth most populous city in the United States and top-10 in terms of spatial extent. It’s well known that the impact cities can have on the surrounding environment correlates  with the architectural characteristics and spatial extent of the city. Houston’s notably large spatial extent and high population pave the way for high levels of human-produced emissions within its transportation infrastructure.These emissions and its proximity to the Gulf of Mexico, make Houston especially susceptible to environmental changes related to urban development.
+    The Houston metropolitan area is the fourth most populous city in the United States and top-10 in terms of spatial extent. It’s well known that the impact cities can have on the surrounding environment correlates with the architectural characteristics and spatial extent of the city. Houston’s notably large spatial extent and high population pave the way for high levels of human-produced emissions within its transportation infrastructure. These emissions and its proximity to the Gulf of Mexico, make Houston especially susceptible to environmental changes related to urban development.
 
-    A team of researchers from the University of Alabama in Huntsville temporally averaged daily Aerosol Optical Depth (AOD) measurements from NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS) Terra and Aqua satellites (MODIS product [MCD19A2](https://ladsweb.modaps.eosdis.nasa.gov/missions-and-measurements/products/MCD19A2)) to evaluate decadal changes in AOD over the Houston metropolitan area. The team also utilizes urbanization data from the U.S. Geological Survey (USGS) National Land Cover Database (NLCD) Imperviousness dataset ([NLCD Imperviousness (CONUS) All Years](https://www.mrlc.gov/data/nlcd-imperviousness-conus-all-years)) to visualize how Houston’s urban footprint has changed between 2001 and 2019. The combination of these data with socioeconomic data from NASA’s Socioeconomic Data and Applications Center (SEDAC) poverty level ([CDC/ATSDR SVI Data and Documentation Download | Place and Health | ATSDR](https://www.atsdr.cdc.gov/placeandhealth/svi/index.html)) allow for insights on how urban growth in Houston impacted air quality and how those changes can vary by socioeconomic status (Dataset landing pages below).
+    A team of researchers from the University of Alabama in Huntsville temporally averaged daily Aerosol Optical Depth (AOD) measurements from NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS) Terra and Aqua satellites to evaluate decadal changes in AOD over the Houston metropolitan area. The team utilizes urbanization data from the U.S. Geological Survey (USGS) National Land Cover Database (NLCD) Imperviousness dataset to visualize how Houston’s urban footprint has changed between 2001 and 2019. The combination of these data with socioeconomic data from NASA’s Socioeconomic Data and Applications Center (SEDAC) poverty level allow for insights on how urban growth in Houston impacted air quality and how those changes can vary by socioeconomic status (Dataset landing pages below).
 
     <sup>[1]</sup> University of Alabama-Huntsvile(UAH)
-    <sup>[2]</sup> National Aeronautics and Space Administration (NASA)
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     ### Air Quality and AOD
 
-   Aerosols can have a variety of implications for the general public. In terms of air quality, aerosols can affect the air quality with high concentrations of pollutants that may pose a risk to public health. The highest risk comes from power plants where the level of emissions are the highest. In-situ measurements, those at a fixed location that measure aerosol concentrations, coupled with global satellite observations help scientists study air quality. AOD measured by the MODIS Terra and Aqua instruments is available globally every 1-2 days and aids researchers identify trends in aerosol concentrations to help inform decision makers.
+   Aerosols can have a variety of implications for the general public. In terms of air quality, aerosols can affect the air quality with high concentrations of pollutants that may pose a risk to public health. The highest risk comes from power plants where the level of emissions are the highest. In-situ measurements of aerosol concentrations, measurements taken at a fixed location, coupled with global satellite observations help scientists study air quality. AOD measured by the MODIS Terra and Aqua instruments is available globally every 1-2 days and aids researchers identify trends in aerosol concentrations to help inform decision makers.
 
-   In recent years, pollution sources have been regulated by the Environmental Protection Agency (EPA) which has found ways to reduce the amount of emissions. The EPA established the National Ambient Air Quality Standards (NAAQS) to regulate emissions to better protect public health. The NAAQS is established under the Clean Air Act and regulates pollutants such as carbon monoxide, sulfur dioxide among others.
+   In recent years, pollution sources have been regulated by the Environmental Protection Agency (EPA) which has found ways to reduce the amount of emissions. The EPA established the National Ambient Air Quality Standards (NAAQS) to regulate emissions to better protect public health. The NAAQS included in the Clean Air Act provides regulation of pollutants such as carbon monoxide, sulfur dioxide among others.
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     ### Aerosol Optical Depth Compared to Houston Urbanization
 
-    Temporal averages of AOD concentrations from 2000-2009 and 2010-2019 are used to infer insights in the changes in air quality for Houston, TX. Comparing the differences of these two time periods indicates that as the city limits have expanded over the last 20 years, AOD has increased along the leading edge of urban growth (Figure 3). As population grows in these regions, emissions from human activity typically increase resulting in higher aerosol concentrations and lower air quality. Alternatively, areas with little urban growth over the last 20 years do not show significant changes in aerosol concentrations. Note that while AOD changes are not significant, this does not necessarily mean that these areas have good air quality. For example, the area around the George Bush Intercontinental Airport (IAH) has high aerosol concentrations for the entire 20-year observational period associated with air traffic (scroll down for further analysis). AOD near Galveston Bay and along the Gulf Coast show a significant reduction in the aerosol concentrations potentially relating back to implementation of NAAQS (see current [NAAQS table](https://www.epa.gov/criteria-air-pollutants/naaqs-table)). Air quality standards for Sulfur Dioxide took effect in 2010 while Ozone and Particle Pollution took effect in December 2015 and could be reflected in decadally-averaged AOD measurements for 2010-2019. Using AOD measurements with socioeconomic data provides insights about how air quality has changed over the last 20 years and how different communities are affected by these changes. 
+    Temporal averages of AOD concentrations from 2000-2009 and 2010-2019 are used to infer insights in the changes in air quality for Houston, TX. Comparing the differences of these two time periods indicates that as the city limits have expanded over the last 20 years, AOD has increased along the leading edge of urban growth (Figure 3). As population grows in these regions, emissions from human activity typically increase resulting in higher aerosol concentrations and lower air quality. Alternatively, areas with little urban growth over the last 20 years do not show significant changes in aerosol concentrations. Note that while AOD changes in these areas are not significant, this does not necessarily mean that these areas have good air quality. For example, the area around the George Bush Intercontinental Airport (IAH) has high aerosol concentrations for the entire 20-year observational period associated with air traffic (scroll down for further analysis). AOD near Galveston Bay and along the Gulf Coast show a significant reduction in the aerosol concentrations potentially relating back to implementation of NAAQS (see current NAAQS table). Air quality standards for Sulfur Dioxide took effect in 2010 while Ozone and Particle Pollution took effect in December 2015 and could be reflected in decadally-averaged AOD measurements for 2010-2019. Using AOD measurements with socioeconomic data provides insights about how air quality has changed over the last 20 years and how different communities are affected by these changes.  
 
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     datetime='2000-01-01'
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     ## AOD Timeseries for Western Houston
-    Unlike the Galveston Bay area, the monthly and spatially averaged time series of AOD for the Western Suburbs of Houston, TX shows a trend where there is a small, statistically insignificant increase over the time period of 2000 to 2019. Note that the spatial pattern of difference in decadal mean AOD between the second and first decade of this century shows a localized increase that correlates to urbanization. Thus the trend of a small increase in AOD time series could be due to vehicular and other urban sources of pollution counteracting the effects of the Clean Air Act.
+    Unlike the Galveston Bay area, the monthly and spatially averaged time series of AOD for the Western Suburbs of Houston, TX shows a trend where there is a small, statistically insignificant increase over the time period of 2000 to 2019. Note that the spatial pattern of difference in decadal mean AOD between the second and first decade of this century shows a localized increase that correlates to urbanization. The small increase in AOD concentrations could be potentially explained by vehicular and other urban sources of pollution counteracting the effects of the Clean Air Act.
 
     <Chart
       dataPath={new URL('./west_houston_adjusted.csv', import.meta.url).href}