The Air Quality Revolution Brewing on Our Roads

The electric car push is about carbon. You know the logic: If we all switch to EVs, and if we power those EV with mostly renewable energy, then the world could slash the amount of carbon dioxide emitted by the transportation sector. The electrification effort is so centered on fighting climate change that it’s easy to forget there’s another big, shiny benefit of switching from gas engines to battery power: cleaner air.

CO2 isn’t the only thing that comes out of a tailpipe, after all. Cars also spew volatile organic compounds (VOCs), nitrous oxides (NOx), and fine particulate matter into the atmosphere with every gallon of gasoline they use. Long before environmentalists viewed cars as a climate villain, they saw internal combustion as a public enemy that poisoned the air. Cars made the smog that obscured the mountains in Los Angeles, and they have caused higher rates of health problems like asthma, birth defects, and premature deaths.

To be sure, EVs are not pollution-free. They tend to be heavy, which increases the rate at which tires break down and shed microparticles. It takes carbon emissions to make lithium-ion batteries. An EV’s pollution benefits are only as good as the electricity that powers it. Even so, the EV era could help Americans breathe easier, and new studies are beginning to show just how much a difference electrification can make.

Here in California, electric vehicles have become a common sight — this year they reached 25 percent of total car sales. To quantify the health benefits of this evolving automotive fleet, researchers at the University of Southern California’s Keck Medical Center studied a variety of ZIP codes across the state where the adoption of zero-emission vehicles jumped by tenfold between 2013 and 2019. They compared that vehicle data against air pollution numbers and asthma-related ER visits in the same places, finding a significant reduction in both. The numbers should be trending even better by now. Across California, zero-emission vehicle adoption has soared past 20 per 1,000 people, compared to 14.1 per 1,000 people at the end of the study’s time period.

Another study, from March 2023, looked at 30 major U.S. metropolitan areas through the lens of the EPA’s air quality model health impact tools. The goal: to see which places would gain the most from a major surge where nearly all drivers owned EVs by 2050. L.A. led the way, with an estimated 1,163 premature deaths prevented every year by better air quality, corresponding to more than $12 billion in health benefits. New York City, Chicago, the cities of California’s Central Valley, and Dallas followed close behind.

Joshua Linn, a professor at the University of Maryland who studies environmental economics, released his own model of EV air pollution gains this January, which put a rough price tag on both the climate and health benefits of EV adoption. A few years ago, he told me, it was more difficult to demonstrate that the electrification of cars would create a positive effect. Gasoline engines had gotten more efficient, making it a little less damaging to choose combustion when buying another car. A few older studies found that electrification actually could be worse for air quality — but, he said, those studies presumed the country would keep burning mostly fossil fuels for its electricity, which means atmospheric pollution from burning coal or gas would skyrocket alongside America’s demand for electricity.

That’s not what happened. With today’s rising use of renewable energy, he says, it’s clear EV adoption will lead to better air quality along with the associated gains in human health. “The cleaner grid wins,” he says. “The power sector is just getting so much cleaner. We anticipate that, over the next 10 or 15 years, buying a plug-in vehicle now and charging it over that vehicle's lifetime is going to be better for the environment than gasoline.”

Even so, it remains tricky to quantify air quality and health impacts. While carbon emissions are seen as a global climate problem, air pollution can be an intensely local issue. A New York City, or Boston, or Atlanta with a high percentage of EVs would see a major decrease in the pollutants coming from cars stuck in gridlock, and people living next to congested roads would breathe much easier. (For a historical analogue, see how families living close to toll booths saw rates of premature births decline with the introduction of the EZ-pass system, when cars began to roll through toll checkpoints rather than sitting there, spewing poison as they fumbled with coins.) But if the U.S. kept burning fossil fuels to make electricity, Linn says, then all those noxious chemicals would simply migrate elsewhere.

“You are moving the pollution away from typically more densely populated areas. You’re moving it towards the power plants, which tend to be located in less dense populated areas. But at the same time, those power plants are shooting that pollution way up into the atmosphere and then it can travel — it can affect pollution far down wind and often in urban areas.” That, he says, is why it’s so important to keep moving the grid toward renewable energy.

Local differences in air pollution also mean that not all areas will experience the air quality benefits of the EV revolution equally. USC’s study was careful to note that because electric cars remain so comparatively expensive, less-affluent neighborhoods have much lower rates of adoption and lower associated gains in air quality. (Research in 2019 claimed that only neighborhoods with average income above $65,000 saw positive air quality effects from EV adoption.)

Some benefits will cross over, Linn says, especially when lost people drive through lower-income neighborhoods in electric vehicles rather than gasoline ones. But the economics of EVs, and their clean-air benefits, still leave a lot to be desired.