Last week, I discussed why consuming oil is bad for U.S. national security. In this post, I’ll look at another reason to consider a plug-in electric vehicle (PEV) – helping the environment. I’ve previously explored  the effect PEVs will have on greenhouse gas (GHG) emissions. It is clear that PEVs have the potential to reduce GHG emissions significantly so long as society also reduces the carbon intensity of the electrical grid. But the environmental benefits of PEVs are not limited to climate change.
Figure 2: It's hard to see through all the smog, but that’s the Brooklyn Bridge in NYC in 1988. (Source )
PEVs also benefit local air quality, which might matter a lot if you live in a city with poor air quality . Despite enormous strides in the U.S. to reduce air pollution, the EPA estimated  in February of this year that nearly 127 million Americans live in areas where air quality concentrations are above the National Ambient Air Quality Standards (NAAQS). The Clean Air Act requires the EPA to establish and periodically update and evaluate the NAAQS. While air quality has improved significantly since 1990, nearly half of Americans still face air quality-related health risks, including decreased lung function, aggravated asthma, and premature mortality.
Air pollution primarily comes from stationary fuel combustion, industrial processes, and vehicles. Transportation mainly contributes to two air pollution problems: ground-level ozone and particle pollution. Particle pollution  or particulate matter (PM) consists of solid particles and liquid droplets in the air; coal fired power plants, as well as diesel vehicles including cars, trucks, and buses, are some of the sources of PM. Ground-level ozone , a serious air pollutant also known as smog, results when sunlight reacts with oxides of nitrogen (NOx) and volatile organic compounds (which are components, for example, of vehicle exhaust).
The health effects of air pollution include decreased lung function, respiratory infection, and even increased risk of heart attacks and strokes under certain conditions. While the U.S. EPA and state governments are moving ahead with regulations that improve the air quality for Americans, most people (especially in urban areas) remain at risk of effects from excessive ozone and PM. The American Lung Association recommends the EPA reduce air pollution from vehicle tailpipes. One way consumers can help is by purchasing vehicles with lower tailpipe emissions such as PEVs.
The more miles Americans travel in passenger vehicles powered by electric motors, the more local air quality will improve according to a study  completed by the Electric Power Research Institute (EPRI) and the National Resources Defense Council (NRDC). It is difficult to quantify air quality benefits from using PEVs since air pollution can come from multiple sources, including vehicle tailpipes as well as power plants. All-electric vehicles in cities will almost certainly improve local air quality since a mile traveled that is powered by electricity does not produce any vehicle emissions and the power plants that produce the electricity are often located away from city centers. For plug-in hybrid electric vehicles, those improvements are tempered by the percentage of miles that rely on the gasoline or diesel-powered backup energy source rather than by the batteries. In fact, using PEVs can result in more local air pollution at the electricity generation source, especially if the source is a coal power plant. This potential problem underscores another reason (in addition to the goal of reducing GHG emissions) that we should work on reducing power plant pollution as we green the vehicle fleet.
PEVs will not end air pollution in the United States, but increasing the market penetration of these vehicles will help reduce air pollution in cities throughout the country. In the next post, I’ll look into how the financial numbers might work out with a PEV for your next vehicle purchase.
Nick Nigro is a Solutions Fellow