Leveraging High-Resolution Satellite-Derived NO Estimates to Evaluate NO Exposure Representativeness and Socioeconomic Disparities.

Research has typically estimated NO concentrations over several kilometers; thus, NO data at finer spatial resolution remain limited. This study used tropospheric NO data from the TROPOspheric Monitoring Instrument (TROPOMI) and traffic-related land use parameters to estimate long-term average NO concentrations at a spatial resolution of 500 m in South Korea from 2018 to 2022. Our satellite-land use hybrid regression model showed reasonably high predictability with a cross-validation of 0.81, mean absolute error of 2.28 ppb and root mean squared error of 2.85 ppb. Leveraging these high-resolution data, we assessed the representativeness of ground monitors for population exposure by comparing population-weighted NO concentrations from estimated and measured data. Across 17 metropolitan cities and provinces, the ratios of population-weighted estimated to measured NO ranged from 0.62 to 1.12, with the ratio of 1 exhibiting the most representative monitoring networks. We further investigated disproportionate NO exposures based on socioeconomic status, revealing that NO exposures were consistently higher in local districts with higher socioeconomic status because of the unique historical backgrounds of rapid economic development and urban infrastructure design in South Korea. Using high-resolution NO data can lead to more comprehensive and precise exposure assessments, enhancing public health and regulatory applications.