By Keck School of Medicine of USC
When California neighborhoods increased their number of zero-emissions vehicles (ZEV) between 2019 and 2023, they also experienced a reduction in air pollution. For every 200 vehicles added, nitrogen dioxide (NO₂) levels dropped 1.1%. The results, obtained from a new analysis based on statewide satellite data, are among the first to confirm the environmental health benefits of ZEVs, which include fully electric and plug-in hybrid cars, in the real world. The study was funded in part by the National Institutes of Health and just published in The Lancet Planetary Health.
While the shift to electric vehicles is largely aimed at curbing climate change in the future, it is also expected to improve air quality and benefit public health in the near term. But few studies have tested that assumption with actual data, partly because ground-level air pollution monitors have limited spatial coverage. A 2023 study from the Keck School of Medicine of USC using these ground-level monitors suggested that ZEV adoption was linked to lower air pollution, but the results were not definitive.
Now, the same research team has confirmed the link with high-resolution satellite data, which can detect NO₂ in the atmosphere by measuring how the gas absorbs and reflects sunlight. The pollutant, released from burning fossil fuels, can trigger asthma attacks, cause bronchitis, and increase the risk of heart disease and stroke.
“This immediate impact on air pollution is really important because it also has an immediate impact on health. We know that traffic-related air pollution can harm respiratory and cardiovascular health over both the short and long term,” said Erika Garcia, PhD, MPH, assistant professor of population and public health sciences at the Keck School of Medicine and the study’s senior author.
The findings offer support for the continued adoption of electric vehicles. Over the study period, ZEV registrations increased from 2% to 5% of all light-duty vehicles (a category that includes cars, SUVs, pickup trucks and vans) across California, suggesting that the potential for improving air pollution and public health remains largely untapped.
“We’re not even fully there in terms of electrifying, but our research shows that California’s transition to electric vehicles is already making measurable differences in the air we breathe,” said the study’s lead author, Sandrah Eckel, PhD, associate professor of population and public health sciences at the Keck School of Medicine.
