Space?Based Observational Constraints on NO ₂ Air Pollution Inequality From Diesel Traffic in Major US Cities

Air pollution disproportionately burdens communities of color and lower-income in US cities. We have generally lacked city-wide concentration measurements that resolve the steep spatiotemporal gradients primary pollutants required to describe intra-urban air inequality. Here, we use observations from recently launched TROPospheric Ozone Monitoring Instrument (TROPOMI) satellite sensor physics-based oversampling nitrogen dioxide (NO2) disparities with race, ethnicity, income 52 cities (June 2018–February 2020). report average US-urban census tract-level NO2 inequalities 28 ± 2% (race-ethnicity combined), many populous experiencing even greater inequalities. Using inventories, find diesel traffic is dominant source disparities, a 62% reduction emissions would decrease race-ethnicity by 37%. add evidence TROPOMI resolves tract-scale differences using relationships urban segregation patterns spatial variability column-to-surface correlations.