Daily Satellite Observations of Nitrogen Dioxide Air Pollution Inequality in New York City, New York and Newark, New Jersey: Evaluation and Application

[Image: see text] Urban air pollution disproportionately harms communities of color and low-income communities in the U.S. Intraurban nitrogen dioxide (NO(2)) inequalities can be observed from space using the TROPOspheric Monitoring Instrument (TROPOMI). Past research has relied on time-averaged measurements, limiting our understanding of how neighborhood-level NO(2) inequalities co-vary with urban air quality and climate. Here, we use fine-scale (250 m × 250 m) airborne NO(2) remote sensing to demonstrate that daily TROPOMI observations resolve a major portion of census tract-scale NO(2) inequalities in the New York City–Newark urbanized area. Spatiotemporally coincident TROPOMI and airborne inequalities are well correlated (r = 0.82–0.97), with slopes of 0.82–1.05 for relative and 0.76–0.96 for absolute inequalities for different groups. We calculate daily TROPOMI NO(2) inequalities over May 2018–September 2021, reporting disparities of 25–38% with race, ethnicity, and/or household income. Mean daily inequalities agree with results based on TROPOMI measurements oversampled to 0.01° × 0.01° to within associated uncertainties. Individual and mean daily TROPOMI NO(2) inequalities are largely insensitive to pixel size, at least when pixels are smaller than ∼60 km(2), but are sensitive to low observational coverage. We statistically analyze daily NO(2) inequalities, presenting empirical evidence of the systematic overburdening of communities of color and low-income neighborhoods with polluting sources, regulatory ozone co-benefits, and worsened NO(2) inequalities and cumulative NO(2) and urban heat burdens with climate change.