The growing adoption of electric vehicles in California is already delivering measurable improvements in air quality, according to new research that uses satellite data to track pollution levels across the state.
Researchers at the Keck School of Medicine of the University of Southern California found that neighbourhoods with more zero-emissions vehicles (ZEVs) experienced statistically significant reductions in nitrogen dioxide (NO₂).
The study, published in The Lancet Planetary Health, is among the first to demonstrate these benefits using real-world data rather than models or projections.
Analysing changes between 2019 and 2023, the researchers showed that for every 200 ZEVs added in a neighbourhood, NO₂ levels fell by 1.1%. ZEVs include fully electric cars, plug-in hybrids and fuel-cell vehicles.
Dr Erika Garcia, assistant professor of population and public health sciences at the Keck School of Medicine and the study’s senior author said: ‘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.’
While electric vehicles are often promoted as a long-term climate solution, the findings suggest they can also deliver near-term public health benefits.
Previous studies have struggled to prove this link conclusively, partly because ground-based air quality monitors are unevenly distributed. To overcome this, the USC team turned to satellite observations from the Tropospheric Monitoring Instrument (TROPOMI), which measures NO₂ by analysing how the gas absorbs and reflects sunlight.
The researchers divided California into 1,692 neighbourhoods and combined satellite pollution data with vehicle registration records from the state’s Department of Motor Vehicles. Over the study period, a typical neighbourhood added 272 ZEVs, with registrations rising statewide from 2% to 5% of all light-duty vehicles.
Lead author Dr Sandrah Eckel, associate professor at the Keck School of Medicine 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.’
To ensure the findings were robust, the team carried out multiple checks, including accounting for pandemic-related changes such as reduced travel in 2020. They also confirmed that neighbourhoods adding more petrol and diesel vehicles saw corresponding increases in pollution, and replicated their results using ground-level monitoring data.
Eckel said: ‘These findings show that cleaner air isn’t just a theory – it’s already happening in communities across California.’
The researchers are now examining whether rising ZEV adoption is linked to fewer asthma-related hospital visits, a step that could provide some of the first real-world evidence of direct health benefits from the shift to electric vehicles.
The full research can be read here.
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