Despite major improvements in air quality, racial and ethnic disparities in exposure to nitrogen dioxide (NO₂) pollution have worsened in California over the past four decades. A new study using high-resolution data from 1980 to 2022 found that Hispanic or Latino individuals experienced nearly three times as many days with NO₂ levels exceeding 50µg/m³ in 2020 compared to non-Hispanic White individuals. In 1980, that gap was just 32%.
Researchers used a deep learning framework to estimate daily NO₂ concentrations across California’s 1 km grids, revealing persistent and growing inequities. While overall NO₂ levels declined, relative disparities among Black, Hispanic, Asian, Pacific Islander, and American Indian groups increased. These communities were consistently exposed to more short-term pollution spikes, which are linked to respiratory illness and premature death.
The study’s authors emphasized that “short-term NO₂ exposure is associated with various adverse health outcomes,” and that understanding these disparities is critical for shaping effective environmental health policies. Their model, informed by chemical transport simulations and geospatial data, captured fine-scale variations that traditional monitoring systems often miss.
This research adds a new layer to the environmental justice conversation, showing that even as pollution drops, unequal exposure remains entrenched. It calls for targeted interventions that address not just emissions, but the social and spatial dynamics that leave minority communities more vulnerable.
See: “Racial and ethnic disparities in exposure to short-term NO2 air pollution in California during 1980–2022” (September 15, 2025)
