California neighborhoods with more EVs see better air quality, public health

Neighborhoods in California with higher electric vehicle (EV) adoption rates are experiencing both better air quality and improvements in public health, a new study has found.

For every additional 20 zero-emissions vehicles (ZEVs) per 1,000 people at the zip code level, there was a 3.2 percent drop in the rate of asthma-related emergency room visits, according to the report, published on Thursday in Science of the Total Environment.

The study authors also identified a small suggestive reduction in levels of nitrogen dioxide — a gaseous pollutant that has long contributed to “the reddish-brown haze characteristic of smoggy air in California,” per the state’s Air Resources Board.

“When we think about the actions related to climate change, often it’s on a global level,” lead author Erika Garcia, an assistant professor of population and public health sciences at the University of Southern California’s Keck School of Medicine, said in a statement.

“But the idea that changes being made at the local level can improve the health of your own community could be a powerful message to the public and to policy makers,” she added.

To draw their conclusions, Garcia and her colleagues compared data on total ZEV registration, air pollution levels and asthma-related emergency room visits across the state from 2013 through 2019.

In California, the ZEV umbrella includes full battery-electric, hydrogen fuel cells and plug-in hybrid-electric vehicles, according to the Air Resources Board.

As EV adoption increased within a given zip code, local air pollution levels and emergency room visits also dropped, the authors found.

While EVs have long been recognized for their potential to improve air quality, research exploring the dual benefits of reduced pollution and better health has thus far been hypothetical, the scientists noted.

Garcia and her team analyzed and compared four separate datasets, first obtaining data on ZEVs from the California Department of Motor Vehicles and tabulating the number registered in each zip code.

Then they acquired data from the Environmental Protection Agency on levels of nitrogen dioxide and zip code level asthma-related visits to the emergency room.

Asthma, they explained, is a primary health concern linked to air pollutants such as nitrogen dioxide — which can also cause and worsen other respiratory diseases, as well as problems with the heart, brain and other organ systems.

Lastly, the researchers calculated the percentage of adults in each zip code who held bachelor’s degrees, as educational attainment levels are often used to identify a neighborhood’s socioeconomic status.

In neighborhoods across the state, the scientists found that ZEVs increased from 1.4 to 14.6 per 1,000 people between 2013 and 2019.

However, ZEV adoption was substantially lower in zip codes with poorer rates of educational attainment, according to the study.

For example, a zip code in which 17 percent of the population had a bachelor’s degree experienced an annual increase of about 0.70 ZEVs per 1,000 people.

On the other hand, a neighborhood in which 47 percent of the population had a bachelor’s degree had an annual increase of about 3.6 ZEVs per 1,000 people.

Recognizing this “adoption gap” could help restore environmental justice in communities that have been disproportionately impacted by pollution and related health issues, according to the authors.

At the moment, however, the existing adoption gap “threatens the equitable distribution” of improvements in air quality and health, they concluded.

“We want to make sure that those communities that are overburdened with the traffic-related air pollution are truly benefiting from this climate mitigation effort,” Garcia said.

Moving forward, the researchers suggested that future studies should examine additional impacts of ZEVs, such as emissions related to brake and tire wear.

They also stressed that the ZEV transition is just one piece of the puzzle, as a shift to public transport, walking and biking will also be critical.

“The impacts of climate change on health can be challenging to talk about because they can feel very scary,” senior author Sandrah Eckel, an associate professor of population and public health sciences at the Keck, said in a statement.

“We’re excited about shifting the conversation towards climate change mitigation and adaptation, and these results suggest that transitioning to ZEVs is a key piece of that,” Eckel added.

— Updated at 7:10 p.m.

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