Adoption of electric vehicles tied to real-world reductions in air pollution, study finds

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.

Tracking neighborhood air quality

For the analysis, the researchers divided California into 1,692 neighborhoods, using a geographic unit similar to zip codes. They obtained publicly available data from the state’s Department of Motor Vehicles on the number of ZEVs registered in each neighborhood. ZEVs include full-battery electric cars, plug-in hybrids and fuel-cell cars, but not heavier duty vehicles like delivery trucks and semi-trucks.

Next, the research team obtained data from the Tropospheric Monitoring Instrument (TROPOMI), a high-resolution satellite sensor that provides daily, global measurements of NO₂ and other pollutants. They used this data to calculate annual average NO₂ levels in each California neighborhood from 2019 to 2023.

Over the study period, a typical neighborhood gained 272 ZEVs, with most neighborhoods adding between 18 and 839. For every 200 new ZEVs registered, NO₂ levels dropped 1.1%, a measurable improvement in air quality.

“These findings show that cleaner air isn’t just a theory—it’s already happening in communities across California,” Eckel said.

Electric vehicles and public health

To confirm that these results were reliable, the researchers conducted several additional analyses. They accounted for pandemic-related changes as a contributor to NO₂ decline, such as excluding the year 2020 and controlling for changing gas prices and work-from-home patterns. The researchers also confirmed that neighborhoods that added more gas-powered cars saw the expected rise in pollution. Finally, they replicated their results using updated data from ground-level monitors from 2012 to 2023.

“We tested our analysis in many different ways, and the results consistently support our main finding,” Garcia said.

These results show that TROPOMI satellite data—which covers nearly the entire planet—can reliably track changes in combustion-related air pollution, offering a new way to study the effects of the transition to electric vehicles and other environmental interventions.

Next, Garcia, Eckel and their team are comparing data on ZEV adoption with data on asthma-related emergency room visits and hospitalizations across California. The study could be one of the first to document real-world health improvements as California continues to embrace electric vehicles.

About this research

In addition to Garcia and Eckel, the study’s other authors are Futu Chen, Sam J. Silva and Jill Johnston from the Department of Population and Public Health Sciences, Keck School of Medicine of USC, University of Southern California; Daniel L. Goldberg from the Milken Institute School of Public Health, The George Washington University; Lawrence A. Palinkas from the Herbert Wertheim School of Public Health and Human Longevity Science, University of California, San Diego; and Alberto Campos and Wilma Franco from the Southeast Los Angeles Collaborative.

This work was supported by the National Institutes of Health/National Institute of Environmental Health Sciences [R01ES035137, P30ES007048]; the National Aeronautics and Space Administration Health and Air Quality Applied Sciences Team [80NSSC21K0511]; and the National Aeronautics and Space Administration Atmospheric Composition Modeling and Analysis Program [80NSSC23K1002].