Observing Nitrogen Dioxide Air Pollution Inequality Using High-Spatial-Resolution Remote Sensing Measurements in Houston, Texas.
Mary Angelique G Demetillo, Aracely Navarro, Katherine K Knowles, Kimberly P Fields, Jeffrey A Geddes, Caroline R Nowlan, Scott J Janz, Laura M Judd, Jassim Al-Saadi, Kang Sun, Brian C McDonald, Glenn S Diskin, Sally E Pusede
Author Information
Mary Angelique G Demetillo: Department of Environmental Sciences, University of Virginia, Charlottesville, Virginia 22904, United States. ORCID
Aracely Navarro: Department of Public Health, Emory University, Atlanta, Georgia 30322, United States.
Katherine K Knowles: Department of Environmental Sciences, University of Virginia, Charlottesville, Virginia 22904, United States.
Kimberly P Fields: Carter G. Woodson Institute for African-American and African Studies, University of Virginia, Charlottesville, Virginia 22904, United States.
Jeffrey A Geddes: Department of Earth and Environment, Boston University, Boston, Massachusetts 02215, United States. ORCID
Caroline R Nowlan: Atomic and Molecular Physics Division, Harvard Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, United States.
Scott J Janz: NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, United States.
Laura M Judd: NASA Langley Research Center, Hampton, Virginia 23681, United States.
Jassim Al-Saadi: NASA Langley Research Center, Hampton, Virginia 23681, United States.
Kang Sun: Department of Civil, Structural and Environmental Engineering, University at Buffalo, Buffalo, New York 14260, United States.
Brian C McDonald: Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado 80305, United States. ORCID
Glenn S Diskin: NASA Langley Research Center, Hampton, Virginia 23681, United States.
Sally E Pusede: Department of Environmental Sciences, University of Virginia, Charlottesville, Virginia 22904, United States. ORCID
Houston, Texas is a major U.S. urban and industrial area where poor air quality is unevenly distributed and a disproportionate share is located in low-income, non-white, and Hispanic neighborhoods. We have traditionally lacked city-wide observations to fully describe these spatial heterogeneities in Houston and in cities globally, especially for reactive gases like nitrogen dioxide (NO). Here, we analyze novel high-spatial-resolution (250 m × 500 m) NO vertical columns measured by the NASA GCAS airborne spectrometer as part of the September-2013 NASA DISCOVER-AQ mission and discuss differences in population-weighted NO at the census-tract level. Based on the average of 35 repeated flight circuits, we find 37 ± 6% higher NO for non-whites and Hispanics living in low-income tracts (LIN) compared to whites living in high-income tracts (HIW) and report NO disparities separately by race ethnicity (11-32%) and poverty status (15-28%). We observe substantial time-of-day and day-to-day variability in LIN-HIW NO differences (and in other metrics) driven by the greater prevalence of NO (≡NO + NO) emission sources in low-income, non-white, and Hispanic neighborhoods. We evaluate measurements from the recently launched satellite sensor TROPOMI (3.5 km × 7 km at nadir), averaged to 0.01° × 0.01° using physics-based oversampling, and demonstrate that TROPOMI resolves similar relative, but not absolute, tract-level differences compared to GCAS. We utilize the high-resolution FIVE and NEI NO inventories, plus one year of TROPOMI weekday-weekend variability, to attribute tract-level NO disparities to industrial sources and heavy-duty diesel trucking. We show that GCAS and TROPOMI spatial patterns correspond to the surface patterns measured using aircraft profiling and surface monitors. We discuss opportunities for satellite remote sensing to inform decision making in cities generally.
