
A team of researchers from the Keck School of Medicine of USC have begun to document the impact of electric vehicle adoption in the first study to use real-world data to link electric cars, air pollution and health. Leveraging publicly available datasets, the researchers analyzed a “natural experiment” occurring in California as residents in the state rapidly transitioned to electric cars, or light-duty zero emissions vehicles. The results were just published in the journal Science of the Total Environment.
The team compared data on total zero emissions vehicle registration, air pollution levels and asthma-related emergency room visits across the state between 2013 to 2019. As adoption increased within a given zip code, local air pollution levels and emergency room visits dropped.
The researchers also found that while total zero emission vehicles increased over time, adoption was considerably slower in low-resource zip codes — what the researchers refer to as the “adoption gap.” That disparity points to an opportunity to restore environmental justice in communities that are disproportionately affected by pollution and related health problems.
To study the effects of electric vehicle adoption, the research team analyzed and compared four different datasets. First, they obtained data on zero emission vehicles (which includes battery electric, plug-in hybrid and hydrogen fuel cell cars) from the California Department of Motor Vehicles and tabulated the total number registered in each Zip code for every year between 2013 and 2019.
They also obtained data from U.S. Environmental Protection Agency air monitoring sites on levels of nitrogen dioxide, an air pollutant related to traffic, and Zip code level asthma-related visits to the emergency room. Asthma is one of the health concerns long linked with air pollutants such as NO2, which can also cause and exacerbate other respiratory diseases.
Finally, the researchers calculated the percentage of adults in each Zip code who held bachelor’s degrees. Educational attainment levels are frequently used as an indicator of a neighborhood’s socioeconomic status.
At the Zip code level, for every additional 20 zero emissions vehicles per 1,000 people, there was a 3.2% drop in the rate of asthma-related emergency visits and a small suggestive reduction in NO2 levels. On average across Zip codes in the state, zero emisions vehicles increased from 1.4 to 14.6 per 1,000 people between 2013 and 2019. Zero emission vehicle adoption was significantly lower in Zip codes with lower levels of educational attainment.