A team led by UCLA Fielding School of Public Health researchers has found the levels of fine particulate matter in the air near electric vehicle fast charging stations across Los Angeles County are significantly higher than those measured at urban sites without the stations.

The open-access study is published in the July edition of the journal Environment International. The researchers, from UCLA Fielding and the UCLA Samueli School of Engineering, found the air near Direct Current Fast Charging (DCFC) stations at 50 locations across the county were higher than those measured at urban “background” sites, without fast charging stations, used for comparison, researchers said.

At the charging stations, daily concentrations of PM_2.5 ranged from 7.3 to 39.0 micrograms per cubic meter, while the same analysis at the background sites found concentrations of only 3.6 to 12.4 micrograms per cubic meter.

Our findings suggest that these tiny particles likely come from particle resuspension around the DCFC’s power cabinets. These cabinets convert electricity from the grid into the direct current needed to charge electric vehicle batteries. The cabinets also contain cooling systems to prevent the electronics from overheating, and these cooling fans can stir up dust and particles from internal surfaces. That’s what we think might be one of the reasons for the increased pollutant levels we found.

—Dr. Yuan Yao, a UCLA Fielding scholar and first author of the study

The study team examined air quality at 50 DCFC stations—with a variety of owners and equipment—across 47 cities in Los Angeles County, performing field measurements in communities from Lakewood north to Santa Clarita, and from Malibu on the coast inland to Pomona. For comparison purposes, the researchers also sampled at gas stations and urban background sites across the county and during the same sampling period.

Among all counties in the United States, Los Angeles County had the highest number of EV fast chargers in operation, totaling 1,938 units of some 9,900 across the state of California as of November 2023. There are some 36,000 such units across the US, with 2,200 in Texas, and 2,100 in Florida, respectively.

The result of the Los Angeles County study included measurements as high as 39 and 34 micrograms per cubic meter in cities as far apart as West Hollywood and Santa Clarita, to lower but still concerning measurements of 7.3 and 7.5 micrograms per cubic meter in communities as disparate as Santa Monica and Claremont. The original sources of the particles include a mix of possibilities, ranging from brake and tire wear to dirt and dust, researchers said.

This work was supported by the University of California Office of the President’s Climate Action under grant number R02CP6948.

The team researched DCFC locations through the Alternative Fuel Data Center, US Department of Energy (US Department of Energy, Alternative Fueling Station Locator), and cross-referenced with DCFC owners’ networks. To ensure a representative sample, the researchers used a random selection process to include a wide range of cities within the county and avoid clustering.

Samples were obtained using a variety of certified and validated sampling equipment between February and May 2024, and instruments were synchronized to ensure accuracy and consistency in data collection. Statistical analyses followed using standardized processes and software. Data will be made available on request.

Resources

• Yuan Yao, Muchuan Niu, Haoxuan Chen, Qiao Yu, Qingyang Wu, Yuhang Li, Yijie Zhang, Aydogan Ozcan, Michael Jerrett, Yifang Zhu, Fine particulate matter emissions from electric vehicle fast charging stations, Environment International, Volume 201, 2025, 109581, ISSN 0160-4120, doi: 10.1016/j.envint.2025.109581