Rising EV adoption linked to air pollution decline, study finds

By Phong Ngo February 4, 2026 | 08:58 pm PT

Higher electric vehicle adoption in California, U.S., coincided with lower harmful nitrogen dioxide (NO₂) levels linked to heart disease and respiratory illness, a new study found.

Researchers from the Keck School of Medicine at the University of Southern California analyzed electric vehicle and plug-in hybrid registrations alongside NO₂ levels across 1,692 neighborhoods statewide from 2019 to 2023.

NO₂, a gas released when fossil fuels are burned, is known to trigger asthma attacks, cause bronchitis, and increase the risk of heart disease and stroke.

The study, published last month in The Lancet Planetary Health journal, found that for every 200 new plug-in vehicles registered in a California neighborhood during the study period, NO₂ levels dropped by 1.1%, according to InsideEVs.

"These findings show that cleaner air isn't just a theory–it's already happening in communities across California," Sandrah Eckel, PhD, associate professor of population and public health sciences at the Keck School of Medicine and the study’s lead author, said. "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."

By contrast, neighborhoods that added more gasoline-powered vehicles saw pollution levels rise, the researchers found.

An EV plugged in to a public charging station. Photo from Pexels

The team measured NO₂ concentrations by tracking how the gas absorbs and reflects sunlight, then compared changes with EV and plug-in hybrid registration data from California’s Department of Motor Vehicles. To ensure reliability, the researchers excluded 2020 from the analysis to account for pandemic-related disruptions that may have contributed to temporary declines in pollution.

"We tested our analysis in many different ways, and the results consistently support our main finding," 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.

Beyond local air quality improvements, EVs are associated with lower carbon dioxide emissions, according to EV Powered. An average family EV in the U.K. produces about 50 grams of CO₂ per kilometer, versus around 170 grams for a diesel vehicle, cutting annual emissions by more than 1.5 million grams.